Geological Survey of New South WalesQuarterly Notes

Geological Survey of New South Wales

September 2011 No 137

© State of New South Wales through the Division of Resources and Energy, 2011

Papers in Quarterly Notes are subject to external review. External reviewer for this issue was Dr Barry Webby, Honorary Associate, Earth and Planetary Sciences, Macquarie University. His assistance is appreciated.

Quarterly Notes is published to give wide circulation to results of studies in the Geological Survey of New South Wales. Papers are also welcome that arise from team studies with external researchers. Contact: john.greenfield@industry.nsw.gov.au

ISSN 0155-3410

I.G. Percival1, C.D. Quinn2 and R.A. Glen21 Geological Survey of New South Wales,

W.B. Clarke Geoscience Centre, Londonderry, NSW 27532 Geological Survey of New South Wales,

516 High Street, Maitland, NSW 2320

AUTHORS

A review of Cambrian and Ordovician stratigraphy in New South Wales

AbstractWe present a comprehensive review of a significant interval spanning 100 million years in the geological history of New South Wales, listing all currently accepted groups, formations and constituent members of Cambrian and Ordovician age. These units are briefly described and placed in their tectonic context, with the most up-to-date biostratigraphic and isotopic age dating assembled to constrain correlations (depicted in 25 representative stratigraphic columns) across orogenic belts and terranes. Rock units previously assigned a Cambrian or Ordovician age, whose names are now obsolete, redundant or are known to be younger, are also discussed or listed in an appendix. The increasingly diverse literature on the Cambrian and Ordovician stratigraphy of the state is reflected in an extensive bibliography. This review is intended to benefit the mineral exploration industry, research workers both locally and overseas, and geological mapping generally by providing a ready reference to Cambrian and Ordovician rocks in NSW. It also indicates where current data are insufficient to resolve precise age determinations and correlations, thereby highlighting those areas that require further work before a complete synthesis of the early Palaeozoic geological history of NSW can be undertaken.Keywords: Cambrian, Ordovician, New South Wales, stratigraphy, biostratigraphy, Delamerian Orogen, Lachlan Orogen, New England Orogen, Narooma Terrane.

IntroductionThe Cambrian and Ordovician periods span an interval of almost exactly 100 million years, from 542–443 Ma, during which the New South Wales portion of the Tasmanides expanded from restricted accumulation on the Delamerian continental margin and a few distant seamounts during the Cambrian, to an extensive complex of depositional settings including back-arc basin, volcanic island arc and offshore terranes

throughout the Ordovician (Glen 2005; Glen et al. 2009). Cambrian rocks are therefore, in comparison with Ordovician strata, relatively poorly represented areally in NSW. They are best known from the Koonenberry Belt in the far west of the state (Figure 1), the subject of a regional mapping program completed by the Geological Survey of New South Wales (Greenfield et al. 2010). As a result of numerous palaeontological studies in

2 September 2011

The information contained in this publication is based on knowledge and understanding at the time of writing (June 2011, revised October 2011). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of the Division of Resources and Energy, or the user’s independent adviser.

Production co-ordination: Geneve Cox

Geological editor: Simone Meakin

Geospatial information: Cheryl Hormann

Layout and charts: Carey Martin

Cover photograph: View towards Dunhill Bluff from Fossil Hill, showing the thin-bedded Fossil Hill Limestone and the lower part of the overlying massive Belubula Limestone. Both units are of Late Ordovician age. (Photographer: S Meakin).

Contents

Abstract 1

Introduction 1

Delamerian Orogen 5

Koonenberry Belt 5

Thomson Orogen 13

Lachlan Orogen — continental margin terranes 13

Albury–Bega Terrane 14

Hermidale Terrane 19

Oceanic crust and associated units 20

Macquarie Arc 21

Narooma Terrane 26

New England Orogen 27

Tamworth Belt 27

Port Macquarie Block 28

Synthesis 28

Acknowledgements 29

References 29

Appendix 39

the past two decades, the stratigraphy of this region is much better known than was the case for the synthesis of Shergold et al. (1985), which was largely reliant on unpublished thesis mapping by Warris (1967). The present review summarises the most recently available biostratigraphic data for the Koonenberry Belt to enable better-constrained correlation with other regions in the Delamerian Orogen, such as those in the Flinders Ranges of South Australia. Elsewhere in NSW, very localised occurrences of fossiliferous ‘Middle’ Cambrian rocks (represented by limestone clasts) have been documented from Batemans Bay on the south coast, and in blocks along the Peel–Manning Fault system in the New England Orogen southeast of Tamworth. Cherts at the base of the succession at Narooma on the south coast are of Late Cambrian age, and the Adaminaby Group in this area also spans the Cambro-Ordovician boundary (Glen et al. 2004). Though direct age control is lacking, serpentinite in the Port Macquarie Block is inferred to be Cambrian.

Ordovician rocks occupy approximately 20% of surface exposures in NSW (Figure 2), with a considerably greater subsurface extent. They host some of the most productive metalliferous deposits in the state. Largely due to their economic importance these rocks have been the focus of recent and continuing mapping programs and associated research studies by the Geological Survey of New South Wales and other institutions. A large number of publications describing Ordovician rocks in NSW, many in specialist journals, have appeared since the Australasia-wide synthesis of Webby et al. (1981). It is therefore timely to review the stratigraphic nomenclature established over the past three decades in order to provide a convenient synthesis from which to develop local and state-wide correlations. For that part of the Macquarie Arc in central NSW, the recent stratigraphic review of Percival and Glen (2007) stands with some minor revisions. That review was largely built on the results of regional mapping programs for the Bathurst, Dubbo and Forbes 1:250 000 sheet areas, combined with substantial research input from CODES (Centre of Excellence in Ore Deposits, at the University of Tasmania). Extensive deep marine basins dominated by clastic sedimentary rocks of turbiditic origin, associated pelagic deposits and graptolitic shales, form the Albury–Bega Terrane and Hermidale Terrane in the centre and south of NSW (modified by Glen et al. 2009 after Glen 2005). Together with the chert-dominated oceanic terrane localised around Narooma on the far south coast (Glen et al. 2004), these deep marine sequences have only relatively recently become stratigraphically subdivisible using conodont-based biostratigraphic zones. This allows more precise correlations with the well-known turbidite-dominated and graptolitic shale successions of Victoria, the stratigraphy of which were recently synthesised by VandenBerg et al. (2000), Fergusson and

3Quarterly Notes

Figure 1. Schematic map of the New South Wales portion of the southern Tasmanides showing distribution of Cambrian rocks in a) Delamerian Orogen and b) New England Orogen. Numbers refer to stratigraphic sequences discussed in text and depicted in Figure 5.

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Figure 2. Schematic map of the New South Wales portion of the southern Tasmanides showing distribution of Ordovician rocks in a) Delamerian Orogen and b) Lachlan Orogen, New England Orogen and Narooma Terrane. Numbers refer to stratigraphic sequences discussed in text and depicted in Figure 5.

5Quarterly Notes

VandenBerg (2003), and Glen et al. (2009). Ordovician rocks of the New England Orogen are sparsely represented by shallow water lithologies including limestone (some reworked into younger strata) along the Peel Fault, together with deep water sediments and pillow basalts of an accretionary complex in the Port Macquarie region. Although areally restricted, they provide critical tie points in correlations to rocks of the Lachlan Orogen.

Chronostratigraphic subdivisions of the Cambrian and Ordovician periods have been the subject of ongoing revision in recent years. For the Ordovician we use a timescale based on that of Sadler et al. (2009), and for the Cambrian that of Shergold and Cooper (2004), modified internally with international subdivisions recommended by the respective stratigraphic subcommissions and ratified by the International Commission on Stratigraphy (Ogg et al. 2008). The ICS timescale adopts a bipartite subdivision of the Cambrian into Early and Late, but to facilitate Australia-wide correlations of Cambrian rocks already in the literature, the currently accepted central and northern Australian trilobite zonation for ‘Middle’ and Late Cambrian time (Figure 3) is also employed here (based on the recent review of Cambrian biostratigraphy in Australia by Kruse et al. 2009), with the informal status of ‘Middle’ Cambrian designated by use of diacritical marks. We follow Laurie (2006, figure 3) in placing the Early–‘Middle’ Cambrian boundary in the latest Ordian, with the Mindyallan–Idamean boundary taken to be the end of the ‘Middle’ Cambrian. Essentially the Australian ‘Middle’ Cambrian equates to Series 3 of the ICS Cambrian timescale. For biostratigraphic subdivisions of the Ordovician (Figure 4), we use the Australasian graptolite-based zonal scheme of VandenBerg and Cooper (1992), together with a conodont biozonation being developed for eastern Australia (Percival et al. in prep.). Statewide correlations of significant Cambrian and Ordovician strata are discussed in the text (with currently accepted stratigraphic names shown in bold font), and these are depicted in Figure 5.

Glen (2005) reviewed the stratigraphy and tectonic evolution of the Tasmanides of eastern Australia, which in NSW includes the continental margin of the Delamerian Orogen in the far west of the state (including largely sedimentary rocks of the Koonenberry Belt), the poorly known Thomson Orogen in the northwest, the New England Orogen occupying the northeastern corner, and the intervening Lachlan Orogen that largely dominates the central and southern regions of NSW. New terminology has recently been introduced (Glen et al. 2009) for Ordovician terranes in the Lachlan Orogen. Within NSW, these include the Albury–Bega Terrane (incorporating turbidite-dominated successions and overlying Late Ordovician black shales west and east of the Macquarie Arc), and the Hermidale Terrane (represented by the Girilambone Group in central NSW).

Restricted to a small area of exposure on the far south coast of the state, the Narooma Terrane (Glen et al. 2004) was accreted to the Albury–Bega Terrane during the Late Ordovician. The stratigraphy of one or more poorly known and as-yet unnamed oceanic floor terrane(s) associated with serpentinised belts in southern NSW is the focus of current work.

Delamerian OrogenFurther details of the stratigraphic units discussed in the following section are provided in Greenfield et al. (2010). Only the most significant fossil occurrences necessary to support biostratigraphic correlations are given in this review; full listings are presented in Percival (2010).

Koonenberry Belt (Figure 5, columns 1–5)

Mutawintji–Mount Wright area (Figure 5, column 1)Early and ‘Middle’ Cambrian rocks older than ~500 Ma, of mostly shallow water lithologies in the central Koonenberry Belt, are assigned to the Gnalta Group (originally named by Warris 1967; redefined by Percival, in Greenfield et al. 2010). The base of the oldest formation, the Mount Wright Volcanics, is not exposed, but this unit (at least 1375 m thick) is presumed to be as old as the Atdabanian (Early Cambrian, Figure 3). The Coonigan Formation is the topmost unit of the Gnalta Group, directly underlying the Delamerian unconformity, and may be as young as late Templetonian (‘Middle’ Cambrian).

First recognised by Warris (1967), the Mount Wright Volcanics was redefined by Crawford et al. (1997) as consisting primarily of calc-alkaline andesite and dacite with minor basaltic andesite, intruded by microdolerite to microdiorite dykes, overlying a lower section comprised of massive dark cherts interbedded with altered basalts, siltstones, and prominent dolomitised limestones. The limestones contain columnar stromatolites of indeterminate age. Öpik (1976) recorded (without description or illustration) fragments of shelly microfossils including Tommotia, phosphatic brachiopods, Chancelloria spicules and algal structures resembling Vermiculites, from isolated limestone lenses within volcanic rocks in the upper part of the formation. From the same lenses, Kruse (1982) described 13 archaeocyathan species forming his assemblage Fauna 1, to which Zhuravlev and Gravestock (1994) assigned an age equivalent to early Botoman.

Although all known contacts between the Mount Wright Volcanics and the overlying Cymbric Vale Formation (Warris 1967) are faulted, there is unlikely to be a significant time gap between them as Archaeocyathid Fauna 1 of Kruse (1982) is present in allochthonous limestone lenses in both the upper Mount Wright Volcanics and the lower half of the Cymbric Vale Formation. Estimates of the thickness

6 September 2011

Figure 3. Cambrian timescale and biostratigraphic zonation used in NSW, based on a review of Cambrian biostratigraphy in Australia by Kruse et al. (2009). Note that the informal status of ‘Middle’ Cambrian (that approximates Series 3 of the ICS Cambrian timescale) is designated by use of diacritical marks. Placing the Early–‘Middle’ Cambrian boundary in the latest Ordian, with the end of the ‘Middle’ Cambrian equivalent to the Mindyallan–Idamean boundary, follows Laurie (2006, figure 3).

Ma Australian stages

‘Middle’ –Late Cambrian trilobite zonation

Late Cambrian–Early Ordovician conodont zonation

490Warendan Chosonodina herfurthi–

Cordylodus angulatusCordylodus lindstromi

492Datsonian

Mictosaukia perplexaNeoagnostus quasibilobus–Shergoldia nomas

Sinosaukia impages

C. prolindstromi–Hirsutodontus simplex Cordylodus proavus

PayntonianHispidodontus discretus

Hispidodontus appressus Hispidodontus resimus

Teridontus nakamurai494

Rhaptagnostus clarki maximus–Rhaptag. papilioRhaptag. bifax–Neoagnostus denticulatusRhaptag. clarki prolatus–Caznaia sectatrix

Rhaptag. clarki patulus–Caznaia squamosaPeichiashania tertia–Peichiashania quarta

Peichiashania secunda–Prochuangia glabellaWentsuia iota–Rhaptagnostus apsis

Irvingella tropica496

Iverian

498Idamean Stigmatoa diloma

Erixanium sentumProceratopyge cryptica

Glyptagnostus reticulatus

500Glyptagnostus stolidotus

Acmarhachis quasivespa

Erediaspis eretesMindyallan

502 BoomerangianDamesella torosa–Ferenepea janitrix

Lejopyge laevigata

504Goniagnostus nathorstiDoryagnostus deltoides

Ptychagnostus punctuosusUndillan

506 Floran Euagnostus opimus Acidusus atavus

Triplagnostus gibbus

Pentagnostus shergoldi

Pentagnostus praecurrens

Pentagnostus anabarensis508 Templetonian

510Ordian Xystridura negrina association

Redlichia forresti association

Toyonian

512

514

516 Botoman

518

520

522

Atdabanian524

526

528Tommotian

TERR

ENEU

VIA

N‘S

ERIE

S 2’

‘SER

IES

3’FU

RON

GIA

NO

RD.

Stag

e 2

Stag

e 3

?St

age

4St

age

5Dr

umia

nGu

zhan

gian

Paib

ian

Stag

e 9

Stag

e 10

Sibe

rian

stag

es

7Quarterly Notes

Australian Pacifi c Province Open-sea Ma stages graptolite zones conodont zones

444 Bo5 Normalograptus? persculptus

Bolindian

Bo4 Normalograptus? extraordinarus

Amorphognathus ordovicicus446Bo3 Paraorthograptus pacifi cus

448Bo2 (pre-pacifi cus)

Bo1 Climacograptus? uncinatus

450

Eastonian

Ea3–4 Dicranograptus gravis Dicellograptus kirki

Amorphognathus superbusEa2 Diplacanthograptus lanceolatus

452

Diplacanthograptus spiniferus454 Ea1Baltoniodus alobatus subzone

456

Gisbornian

Gi2 Orthograptus calcaratus Baltoniodus gerdae subzone

458Gi1 Nemagraptus gracilis

Baltoniodus variabilis subzone

460Pygodus anserinus

462

Darriwilian

Da4 Archiclimacograptus riddellensis

Pygodus serra

464

Da3 Pseudoclimacograptus decoratus Eoplacognathus suecicus466

468Eoplagnathus variabilisDa2 Undulograptus intersitus

470 Da1 Undulograptus astrodentatus

Ya2 Cardiograptus morsus Baltoniodus norrlandicus

472Yapeenian Ya1 Otricograptus upsilon

Ca3–4Isograptus victoriae maximodivergensIsograptus victoriae maximus

Paroistodus originalis

Baltoniodus navis

474 CastlemainianCa2 Isograptus victoriae victoriae Baltoniodus triangularis

Ca1 Isograptus victoriae lunatus

Oepikodus evae476 Ch1–2 Isograptus primulus

Didymograptus protobifi dusChewtonianBe2–4 Pendeograptus fruticosus 3 & 4 branched

478

Bendigonian Prioniodus elegansBe1 Pendeograptus fruticosus

480

482

Lancefi eldian

La2b Araneograptus murrayi Paroistodus proteus

484La2a Aorograptus victoriae

486 Paltodus deltiferLa1b Psigraptus jacksoni

488 La1a Anisograptus

Cordylodus angulatus

490Rhabdinopora fl abelliformis parabola

UP

PE

RM

IDD

LE

LO

WE

R

CAMBRIAN

KAT

IAN

SAN

DBI

AN

DA

RRIW

ILIA

ND

APIN

GIA

NFL

OIA

NTR

EMA

DO

CIA

NHIRNANTIAN

Am

orph

ogna

thus

trae

rens

is

La3Tetragraptus approximatus

SILURIAN

Figure 4. Ordovician timescale and biostratigraphic zonation used in NSW, based on the graptolite zonation of VandenBerg and Cooper (1992), together with the open sea conodont biozonation. Timescale from Sadler et al. (2009).

8 September 2011

of the Cymbric Vale Formation vary between 1500 m (Warris 1967) and 1900 m (Kruse 1982). Predominant lithologies are tuffs and cherts, the latter generally with a green hue. In the upper part of the formation, two limestone lenses (one allochthonous, the other biohermal) contain Archaeocyathid Fauna 2, which has no species in common with the older assemblage (Kruse 1978, 1982). Many species in this younger fauna also occur in the Syringocnema favus beds in the Arrowie and Stansbury basins of South Australia, of mid to late Botoman age (Zhuravlev & Gravestock 1994; Kruse & Shi, in Brock et al. 2000). The uppermost beds (lithic and feldspathic sandstone, and associated impure iron-rich carbonate) of the Cymbric Vale Formation contain trilobites, brachiopods and monoplacophoran molluscs (Öpik 1976). Additional trilobites described by Jago et al. (1997) and Paterson (2005) high in the upper Cymbric Vale Formation are of late Botoman aspect, confirming the age of Archaeocyathid Fauna 2.

Isotopic dating using SHRIMP II U–Pb analyses of zircons from a tuffaceous bed in the Cymbric Vale Formation, which was interpreted by Paterson (2005) to lie just above the lower archaeocyathid-bearing limestone lenses of Kruse (1982), gave an age of 510.5 ± 2.9 Ma (Black 2007). This is consistent with an age of 510.3 ± 3.2 Ma obtained from slightly higher in this formation (Black 2005). These ages are slightly younger than the early Botoman age derived from correlations of Archaeocyathid Fauna 1 of Kruse (1982).

A disconformable relationship between the Cymbric Vale Formation and the overlying Coonigan Formation (Warris 1967) (uppermost unit of the Gnalta Group) was exposed in a trench excavated on the western limb of the Gnalta Syncline (Roberts & Jell 1990, figure 2). Evidence for the time break is provided by the presence of angular fragments of the Cymbric Vale Formation within basal limestone of the Coonigan Formation, in addition to the occurrence of the upper Ordian trilobite

Redlichia petita Öpik, 1970 in overlying shales. Above these shales, the First Discovery Limestone Member

(first defined in Jell et al. 1985) is at least 115 m thick and forms much of the Coonigan Formation. Girvanella

and algal oncolites occur in the lowermost beds of this limestone, which are overlain by highly fossiliferous limestone with a rich and diverse silicified fauna, comprising molluscs (Runnegar & Jell 1976), corals (Jell & Jell 1976), echinoderms (Jell et al. 1985), sphinctozoan sponges (Pickett & Jell 1983), brachiopods (Roberts & Jell 1990), hyoliths, tommotiids and chancelloriid sponge spicules. Also present in this limestone is an abundant trilobite fauna, of which only a few species have been described by Jell (1975). The diverse assemblage of the First Discovery Limestone Member is typical of the

Peronaspis longinqua or Triplagnostus gibbus zones of the Templetonian Stage (Roberts & Jell 1990). The upper half of the First Discovery Limestone Member consists of interbedded limestone, green siltstone and sandstone,

overlain by about 14 m of white micaceous shale of the uppermost Coonigan Formation. From this shale a diverse trilobite fauna is known (Öpik 1968, 1970, 1975, 1979, 1982; Shergold 1969; Laurie 1988), of essentially the same earliest ‘Middle’ Cambrian age (though possibly extending into the late Templetonian) as that assigned to the First Discovery Limestone Member. Revision of the Australian Cambrian biostratigraphic scheme (Shergold 1996) has merged the concept of Öpik’s Ordian and lower Templetonian stages, correlating the interval occupied by the First Discovery Limestone Member with the late Toyonian.

Late Cambrian to Middle Ordovician formations overlying the Delamerian unconformity in the central Koonenberry Belt are represented by the Mutawintji Group (redefined by Greenfield, Mills & Percival, in Greenfield et al. 2010). Formerly known as the Mootwingee Group, the name was changed at the request of the indigenous custodians of the Mutawintji Historic Site to better reflect its original pronunciation (Sharp 2004). Deposition commenced with basal conglomerate (represented by the Nuchea Conglomerate in the Mutawintji area), that is overlain successively by the Nootumbulla Sandstone, Bynguano Quartzite and Rowena Formation, displaying a rapid transition from fluviatile to shallow marine environments with significant clastic influx derived from an extensive delta (Webby 1978, figure 3; Webby 1983). A comparable succession is recognised in the Scropes Range, south of the Barrier Highway (Figure 5, column 4), although a different set of facies is present there.

The Nuchea Conglomerate (defined by Greenfield & Percival, in Greenfield et al. 2010) was first distinguished in the Mutawintji area by Sharp (2004) where it attains a maximum thickness of about 50 m. The conglomerate, of fluvial origin, is clast-supported and consists of well-polished and highly rounded resistant blue–grey orthoquartzite and metaquartzite pebbles, cobbles and boulders. The formation is also recognised to the south, in the Scropes Range between Wilcannia and Broken Hill (Pahl & Sikorska 2004).

The overlying Nootumbulla Sandstone (redefined by Percival, in Greenfield et al. 2010) comprises ~150–200 m of interbedded red shales, conglomerate lenses, and sandstones, initially feldspathic but becoming more quartzose towards the top (Webby 1978). In its type area on the east limb of the Gnalta Syncline, the base of the Nootumbulla Sandstone is defined by the first appearance of interbedded sandstone and shale above the Nuchea Conglomerate. The Nootumbulla Sandstone is interpreted to have been deposited in a shallow marine environment, probably subject to influxes of deltaic sediment. Late Cambrian fossils are common throughout; Shergold (1971) noted saukiid and tsinaniid trilobites of Payntonian age within the lowermost beds. A thin limestone horizon in the middle part of the formation south of Mount Wright

9Quarterly Notes

yields early Datsonian (Cordylodus proavus conodont Zone) conodonts (Zhen & Percival 2006). Uppermost beds of the Nootumbulla Sandstone contain a prolific fauna dominated by trilobites of early Datsonian (latest Cambrian) age (Shergold 1971). These trilobites, which include Chuangiella and apatokephalids (Droser et al. 1994), remain undescribed.

Conformably overlying the Nootumbulla Sandstone is the Bynguano Quartzite, consisting predominantly of quartzite and cross-bedded sandstone about 330 m thick. Droser et al. (1994) renamed the unit the Bynguano Formation without justification, and on the basis of lithology and long-established priority, the original name of Warris (1967) is retained. Diverse trace fossil assemblages indicative of a shallow marine depositional environment are prolific throughout the formation (Webby 1983, Droser et al. 1994). Both pre-depositional crawling traces (characterised by abundant Rusophycus), and post-depositional tiered burrows have been recognised. Shelly faunas, including trilobites and helicotomid gastropods, are present though few have been named or described. Shergold (1971) mentioned the occurrence of richardsonellinid and leiostegiid trilobites in the lower part of the Bynguano Quartzite, comparable with those in the uppermost Nootumbulla Sandstone, which suggests a similar earliest Datsonian (latest Cambrian) age. Droser et al. (1994) recorded Microagnostus sp. and saukiid trilobites from the basal 50 m of the formation. A younger trilobite assemblage in the upper part of the unit with asaphids, dikelokephalinids and protopliomerids, indicative of an earliest Ordovician (Warendan) age, implies that the Bynguano Quartzite spans the Cambro-Ordovician boundary.

The Bynguano Quartzite is conformably succeeded by the ~1700 m-thick Rowena Formation (Warris 1967) that consists of interbedded quartzose sandstones, siltstones and shales with occasional calcareous beds in the middle. At the base of the formation is an unnamed resistant quartzite up to 18 m thick. Another significant quartzite, the Gundara Quartzite Member (defined by Percival, in Greenfield et al. 2010) occurs in the upper part of the formation and includes a distinctive conglomerate with angular clasts of vein quartz. Shelly fauna, including trilobites (mostly undescribed) and lingulide brachiopods, are present in sandstones and siltstones in the middle part of the Rowena Formation. The lingulide brachiopods were first documented by Fletcher (1964) and have recently been redescribed by Percival and Engelbretsen (2007), who recognised species of Hyperobolus, Lingulobolus, and the new genus Rowenaglossa. Webby (1983) documented the trace fossil Rusophycus from the lower part of the formation above the basal conglomeratic quartzite. Skolithos is also recorded from these beds as well as higher in the formation (Shergold et al. 1982). The trace fossils and lingulide brachiopods suggest a shallow water nearshore

marine environment. Zhen and Percival (2006) deduced an Early Ordovician age (Oepikodus evae conodont Zone) from a small but diverse conodont fauna from a thin calcareous horizon in the lower to middle part of the Rowena Formation. However, this conflicts with an early Darriwilian age derived from the presence of two fossils — the trilobite Prosopiscus tatei described from the Rowena Formation by Paterson (2006), and Arandaspis sp., identified by Young (2009) from a single fish plate impression in the upper part of the Rowena Formation — that also occur in the Stairway Sandstone in the Amadeus Basin. The discrepancy between the age based on conodonts, and that suggested by Prosopiscus tatei and Arandaspis, might be resolved if the horizon in which the trilobite occurs lies within the upper (rather than the middle) part of the Rowena Formation. Alternatively, there may be an unrecognised disconformity within the middle part of the unit, with the lower part of the Middle Ordovician unrepresented.

Mount Arrowsmith (Figure 5, column 2)A Cambrian sequence correlated with the Gnalta Group occurs on the western flank of Mount Arrowsmith, at the northern end of the Koonenberry Belt (Figure 1). The sequence was first studied by Warris (1967, 1969) who established the stratigraphic terminology that remains in use, and by Wopfner (1967) who first published a detailed map of the area. The stratigraphy has recently been revised by Brock and Percival (2006). The oldest Cambrian unit, the Pincally Formation, is at least 260 m thick, but as its base is not exposed the relationship with the underlying Neoproterozoic Kara Formation is undetermined. Poorly exposed grey–green phyllitic siltstone and fissile shale comprise most of the Pincally Formation, with a carbonate lens in the lower third and three prominent thin-bedded limestones in the upper third of the unit. The diverse microfauna recovered from the limestones, which includes chancelloriid sponge spicules, lingulate brachiopods, molluscs, hyolithids, hyolithelminthes and echinoderm sclerites (Brock & Percival 2006), indicates a shallow marine setting. This assemblage is closely comparable with that from the First Discovery Limestone Member of the Coonigan Formation, supporting an identical latest Early Cambrian age (Toyonian, or Ordian–early Templetonian), based on the presence of Pelagiella madianensis in the upper part of the Pincally Formation.

The Pincally Formation is conformably overlain by the Wydjah Formation, with the base of the latter unit marked by the appearance of a distinctive cross-bedded, white quartz-rich sandstone (Brock & Percival 2006). The Wydjah Formation is readily subdivisible into a lower and an upper upwards-coarsening sand-dominated sequence (both culminating in conglomeratic layers), separated by the Pimpira Member that consists of four to five prominent dolostone beds (and numerous thin and intermittent

10 September 2011

dolostones) separated by recessive phyllitic siltstones and shales. Total thickness of the Wydjah Formation is 250 m, comprising 87 m for the lower unit, 74 m for the Pimpira Member (including 8–9 m total thickness of dolostones), and 89 m for the upper unit (Brock & Percival 2006). The upper and lower sandstone units are generally unfossiliferous. Several beds of granule conglomerate, each up to 0.5 m thick and characterised by detrital feldspar and volcanic debris, occur in the middle Pimpira Member. A similar layer with angular clasts both of volcanics and granite is found ~10 m below the top of the unit (K.J. Mills & R.A. Glen, field observations 2006). The provenance of the volcaniclastic horizons is presently unresolved, although they may be related to similar beds present in the slightly older Cymbric Vale Formation of the Gnalta area to the south.

Dolostones of the Pimpira Member have yielded a faunal assemblage comparable to that in the Pincally Formation, though slightly less diverse. The chaotic brecciated appearance of the upper dolostone beds, which are also characterised by large algal oncolites, suggests very shallow water and a well agitated depositional environment, possibly a lagoon affected by periodic storms. Age is latest Early Cambrian (Ordian–early Templetonian, or Toyonian), similar to the underlying Pincally Formation, based on the presence of Pelagiella madianensis in the basal beds of the Pimpira Member (Brock & Percival 2006).

The absence of sandstones distinguishes the conformably overlying Wyarra Shale, defined by Brock and Percival (2006), from the Wydjah Formation. The Wyarra Shale is estimated to be about 50 m thick and is dominated by strongly cleaved, unfossiliferous maroon, purple and khaki shales. It is either unconformably overlain by, or is faulted against, the Ordovician Pimbilla Tank Group immediately to the east.

The Pimbilla Tank Group (defined by Percival, in Greenfield et al. 2010) includes in ascending order, the Yandaminta Quartzite, Tabita Formation, and Pingbilly Formation. These formations, first defined by Warris (1967), are confined to a syncline on the western flank of Mount Arrowsmith and represent post Delamerian Orogeny rock units that correlate with the Mutawintji Group exposed at the northern end of the Koonenberry Belt.

The Yandaminta Quartzite is predominantly quartzite, generally massive but locally cross-bedded, and grading to conglomerate at its northern limit of outcrop. Thickness of the formation varies along strike from 200 m to 65 m (Warris 1967), possibly due to faulting along the lower boundary with the Wyarra Shale. Grey–green shales containing carbonate nodules are common in the middle to upper part of the unit but are generally covered by quartzite scree. A conodont fauna obtained from the carbonate nodules (Zhen et al. 2003b) is of late Early Ordovician age (Oepikodus evae conodont Zone).

The overlying Tabita Formation is characterised by interbedded limestone and dolomite. Estimates of the thickness of the Tabita Formation vary from 82–130 m (Zhen, Percival & Webby 2003) to 190 m (Warris 1967). The strata are richly fossiliferous, yielding a varied macrofauna including nautiloids (Crick & Teichert 1983; Stait & Laurie 1985), brachiopods (Paterson & Brock 2003), trilobites (Paterson 2004) and undescribed gastropods and bivalves. Conodonts from the Tabita Formation (Zhen et al. 2001, Zhen, Percival & Webby 2003; Percival et al. 2003) are more diverse than in the underlying Yandaminta Quartzite, but are of essentially the same late Early Ordovician age. Both units were deposited on a shallow marine shelf.

In the core of an overturned syncline on the west flank of Mount Arrowsmith, the youngest shell coquina of the Tabita Formation is conformably succeeded by the Pingbilly Formation, which is approximately 70 m thick. It comprises poorly outcropping micaceous mudstone that occasionally contains subangular to rounded lithic clasts varying from 0.5–40 mm diameter. The age of the Pingbilly Formation is poorly constrained, with only one fossil — the brachiopod Celsiorthis bulancis — having been described from it (Paterson & Brock 2003). As this species also occurs in the underlying Tabita Formation, the two units are likely to be of similar age.

Koonenberry and adjacent areas (Figure 5, column 3)In the Coturaundee Range, the Copper Mine Range Formation, redefined by Mills (in Greenfield et al. 2010), is of probable Early or ‘Middle’ Cambrian age, based on a trace fossil assemblage including Chondrites sp. and Planolites sp. documented by Webby (1984). Sponge spicules and possible paterinide brachiopods in this unit also imply a Cambrian age. The Teltawongee Group (Mills, in Greenfield et al. 2010; previously Teltawongee beds of Mills 1992) consists of weakly metamorphosed graded bedded turbiditic sandstones, exposed in the Wonnaminta and Kayrunnera areas east and west of Koonenberry Mountain (Figure 1). Constituent formations (defined by Mills, in Greenfield et al. 2010) include the Wonnaminta Formation, the Nundora Formation to the west (which may be the oldest unit), the Bunker Creek Formation to the east, and the Depot Glen Formation at the northwestern extremity of the Koonenberry Belt. All these units are fault-bounded, and they may well be equivalent in part. The monotonous lithology and lack of marker units prevent an accurate measurement of the thicknesses of individual formations or the group as a whole. Biostratigraphic evidence for the age of these Teltawongee Group rocks is lacking. The Depot Glen Formation contains a felsic tuff member dated (U–Pb SHRIMP) at 504.5.1 ± 2.6 Ma (Black 2006). On the Kayrunnera 1:100 000 geological sheet, the Bunker Creek Formation has been intruded by the Williams Peak Granite (defined by Gilmore,

11Quarterly Notes

in Greenfield et al. 2010), which has a U–Pb SHRIMP zircon age of 515.1 ± 2.7 Ma (Black 2007), and so must be pre-Ordian.

The Ponto Group of Mills (in Greenfield et al. 2010), at least 5500 m thick, is mainly composed of variably metamorphosed, fine-grained marine clastic rocks (phyllites, schists, fine-grained sandstones and mudstones) of probable deep water origin. The group is subdivided into eight formations (defined or redefined in Greenfield et al. 2010) that outcrop along much of the Koonenberry Belt on the western side of the Koonenberry Fault. From oldest to youngest, they are the Weinteriga Creek Formation (predominantly sandy phyllites in the Grasmere 1:100 000 sheet area), Grasmere Formation (phyllites with feldspathic tuff horizons, quartz–magnetite rocks and mafic units), Noonthorangee Formation (similar to the underlying Grasmere Formation but lacking its strong magnetic character), Koonenberry Formation (green phyllites with minor basaltic flows, tuffaceous and quartz–magnetite rocks, mostly confined to the Cobham Lake 1:100 000 sheet area) and Yandenberry Formation (first defined by Mills, in Greenfield et al. 2010). The Cannela Formation, thought to be correlative with the Noonthorangee Formation, is confined to the Gorge Inlier on Mount Shannon and Mount Poole stations at the northern extremity of the Koonenberry Belt. The Baroorangee Creek Formation, which is mostly exposed on Cymbric Vale station, is more metamorphosed (attaining lower amphibolite grade according to Mills, in Greenfield et al. 2010) than other Ponto Group formations to the east, and relationships between rocks in these two areas are unclear. No fossils have been found in rocks of the Ponto Group. Three feldspathic tuff horizons in the Noonthorangee Formation have been dated using SHRIMP zircon U–Pb analysis at 508.6 ± 3.2 Ma, 511.7 ± 3.5 Ma and 512.0 ± 3.1 Ma (Black 2005), spanning the latest Early Cambrian to earliest Late Cambrian interval. Extrusive rocks that are concentrated in the middle of the Ponto Group, including E-MORB (enriched mid-ocean ridge basalts) tholeiitic pillow lavas, basaltic flows and basic tuffs, have been defined by Vickery and Greenfield (in Greenfield et al. 2010) as the Bittles Tank Volcanics. Also included in this unit are basaltic to doleritic sills which intrude the Ponto, Teltawongee and Grey Range groups. One intrusive rock, dated using SHRIMP zircon analysis at 496.3 ± 3.1 Ma (Black 2005), suggests that the igneous activity responsible for the Bittles Tank Volcanics may have continued after the main pulses of the Delamerian Orogeny; alternatively, the dated sills are much younger than the volcanic unit to which they have been assigned.

Rocks of the Kayrunnera Group (Greenfield, Mills & Percival, in Greenfield et al. 2010) occupy several small basins east of the Koonenberry Fault. Basal conglomerates or quartzites (Williams Creek

Conglomerate; Hummock Formation; Morden Formation) lying directly above the Delamerian unconformity pass upwards into deeper-water sandstones and siltstones (Cupala Creek Formation; Boshy and Watties Bore formations) containing Late Cambrian to earliest Ordovician trilobites. Carbonate beds and lenses are rare until higher in the succession (Funeral Creek and Kandie Tank limestones; Wheeney Creek Formation). The Kayrunnera Group broadly correlates in age with the lower to middle part of the shallow marine Mutawintji Group, and in part represents a deeper water facies equivalent of the latter.

The oldest unit identified in the Kayrunnera Group, the Williams Creek Conglomerate (defined by Greenfield, in Greenfield et al. 2010) was previously recognised as an unnamed basal conglomeratic facies of the Cupala Creek Formation by Powell et al. (1982). It is a coarse polymictic conglomerate, up to 100 m thick, with well-rounded clasts of sandstone, mafic volcanics and chert, assumed by Powell et al. (1982) to be derived from the underlying Copper Mine Range Formation.

The Cupala Creek Formation of Powell et al. (1982) was redefined and subdivided by Greenfield (in Greenfield et al. 2010) into a lower quartzose sandstone- to quartzite-dominated part named the Hummock Formation, that is overlain conformably by the siltstone-dominated Cupala Creek Formation. The Hummock Formation varies in thickness from about 530 m in the Cupala Creek structural outlier, to over 1000 m in the Nuntherungie area. Thickness of the Cupala Creek Formation is also highly variable; the type section in the Cupala Creek area is only 390 m thick, whereas in the Nuntherungie structural outlier the estimated thickness is approximately 4000 m. The sole fossil identified in the Hummock Formation is the brachiopod Billingsella, apparently the same species as occurs in the Cupala Creek Formation (Powell et al. 1982). Trilobites and other fossils (monoplacophoran molluscs, brachiopods) from siltstones and sandstones, with minor fossiliferous calcareous and dolomitic lenses, in the lower part of the redefined Cupala Creek Formation establish the age of these strata as Idamean (early Late Cambrian) (Jell, in Powell et al. 1982).

Southeast of Koonenberry Mountain, the Kayrunnera Group was divided into three formations defined by Webby et al. (1988). The Morden Formation at the base of the group consists of unfossiliferous medium-grained quartzite 1–6 m thick but regionally extensive over 16 km between Morden Creek and Kayrunnera homestead. This unit is conformably overlain by the Boshy Formation, about 94 m thick in the type section located approximately 18 km southeast of Koonenberry Mountain (Webby et al. 1988). Dominant lithologies in this unit include interbedded fine-grained sandstones and siltstones, with minor calcarenites and limestone lenses. Trilobites of latest ‘Middle’ Cambrian (Mindyallan) age were described by Wang et al. (1989)

12 September 2011

from two stratigraphic levels, the lower about one-third up from the base of the formation, and the other in the upper third of the unit. Although some minor differences in faunal composition are apparent between the two levels, all species most likely belong to the late Mindyallan Glyptagnostus stolidotus Zone, possibly near its lower boundary with the underlying Acmarhachis quasivespa Zone (Wang et al. 1989).

The Watties Bore Formation conformably overlies the Boshy Formation, and consists of approximately 2000 m of shales and siltstones, with some well-bedded and laminated impure shaly limestones and minor limestone breccia lenses, interpreted to represent channel deposits by Webby et al. (1988). Trilobites, described by Webby et al. (1988), are present at two levels (separated by only about 100 m) close to the top of the formation, one of latest Cambrian age with the more diverse assemblage of 10 species, and the other of early Tremadoc (basal Ordovician) age characterised by a new species of Hysterolenus. This suggests correlation with the shallow-water facies equivalent Bynguano Quartzite of the Mutawintji Group, which also spans the Cambro-Ordovician boundary.

On Morden Station, the Funeral Creek Limestone (defined by Greenfield & Percival, in Greenfield et al. 2010) — an isolated and apparently overturned allochthonous pod of fossiliferous limestone 20–30 m thick — yielded conodonts of the Late Cambrian Eoconodontus and Cordylodus proavus zones (Zhen & Percival 2006). This limestone has a distinctive brecciated appearance, composed of subrounded to tabular clasts of carbonate up to 20 cm long, suggesting deposition in an agitated shallow water marine environment.

The Kandie Tank Limestone, first described by Pogson and Scheibner (1971) with minor redefinition by Greenfield (in Greenfield et al. 2010), is another isolated limestone pod up to 50 m thick, located east of the northern end of the Coturaundee Range. Undescribed species of Cordylodus in this limestone appear to indicate an age also very close to the Cambro-Ordovician boundary (B.D. Webby, pers. comm. 1995). Thus the Kandie Tank Limestone is slightly younger than the Funeral Creek Limestone, but appears to be contemporaneous with unnamed limestone exposed near Anderson’s Tank on Devon Station in the Dolo Hills to the south (Zhen & Percival 2006).

Outcrop of the Wheeney Creek Formation (defined by Greenfield, in Greenfield et al. 2010), is mainly confined between the Koonenberry Fault on the west, and the Big Wallaby Tank Fault to the east. The formation is up to 500 m thick and is characterised by discontinuous lenses of polymictic conglomerate, quartzite, interbedded psammite and slate, fossiliferous limestone, intraclast limestone and dolomite. Conodonts from limestone at Koonenberry Gap (Zhen et al. 2001, 2003b) are identical to assemblages in the Yandaminta

Quartzite and Tabita Formation at Mount Arrowsmith, i.e. of lower Reutterodus andinus and equivalent Oepikodus evae Zone age, corresponding to the late Bendigonian to early Castlemainian interval (Figure 4).

Bilpa–Comarto area, Scropes Range and Dolo Hills (Figure 5, column 4)The basal unit of the Mutawintji Group in the Scropes Range area, largely exposed south of the Barrier Highway, is the Bilpa Conglomerate. Packham (1968a) and Webby (1983) first noted this unit, which was subsequently informally named by Pahl and Sikorska (2004) and formally described by Greenfield and Percival (in Greenfield et al. 2010). It is a very poorly sorted, pebble to boulder polymictic conglomerate with rounded to angular clasts and a carbonate-rich cement. At the base of the unit, clasts include mafic volcanic rock (very common), phyllite, psammite, vein quartz, gabbro, and felsic tuff, possibly derived from the locally underlying Teltawongee and Ponto groups. Higher in the sequence, quartz-veined rhyolite, plagioclase-phyric andesite, garnet-bearing felsic granitoid, gabbro, psammite, limestone and metapelite pebbles and sub-angular boulders up to 1 m across are present. Although lacking fossils indicative of its depositional age, the conglomerate has yielded rare mudstone pebbles containing the Early Cambrian protolenid trilobite Bergeroniellus (identified by J.H. Shergold; K.J. Mills, pers. comm. 1996). According to Palmer and Rowell (1995), Bergeroniellus is closely related to Hsuaspis, which was described from the upper Cymbric Vale Formation by Jago et al. (1997) and subsequently synonymised with Estaingia by Paterson (2005). The similarity in appearance of these trilobite genera suggests that the fragmentary remains identified as Bergeroniellus could well represent Estaingia, and that these mudstone pebbles may have been derived from exposed parts of the Cymbric Vale Formation, uplifted and eroded during the Delamerian Orogeny.

Conformably overlying the Bilpa Conglomerate in the Scropes Range is the Nuchea Conglomerate (also known from the Mutawintji area: see Figure 5, column 1), which is differentiated by its quartz pebble monomict facies from the polymict Bilpa Conglomerate (Pahl & Sikorska 2004). Thickness of the Nuchea Conglomerate in the Scropes Range is 50–109 m.

The Scropes Range Formation, redefined by Greenfield and Percival (in Greenfield et al. 2010) with spelling corrected from earlier usage of ‘Scopes Range Beds’, is the uppermost unit of the Mutawintji Group in the southern Koonenberry Belt. The formation, which consists of white to maroon cross-bedded quartz sandstone of fluviatile origin in the southwest, grading to shallow marine quartz sandstones to the northeast, is 1385–2012 m thick. Only trace fossils (Webby 1983) and lingulate brachiopods (Percival & Engelbretsen 2007) have been documented from the

13Quarterly Notes

Scropes Range Formation, which is believed to correlate with the Nootumbulla Sandstone, Bynguano Quartzite and Rowena Formation of the Bynguano Range and Mutawintji area.

Warratta, Tibooburra and Mount Poole inliers (Figure 5, column 5)The Warratta Inlier west of Milparinka, and Tibooburra Inlier in the immediate vicinity of Tibooburra, include rocks interpreted to have been deposited following the Delamerian Orogeny (although underlying basement is not exposed, and these inliers may possibly represent parts of the Thomson Orogen). These strata constitute the newly defined Warratta Group (Greenfield, in Greenfield et al. 2010), incorporating the Easter Monday Formation (Vickery, in Greenfield et al. 2010), Jeffreys Flat Formation (Greenfield, in Greenfield et al. 2010), and Yancannia Formation (Mills, in Greenfield et al. 2010). These units are individually named because of their spatial separation (Jeffreys Flat Formation confined to the Warratta Inlier; Easter Monday Formation represented only in the Tibooburra Inlier; Yancannia Formation restricted to the base of the Yancannia Range), but it is likely they were deposited contemporaneously (possibly in one connected depocentre) and therefore probably represent facies equivalents. The lower part of the Jeffreys Flat Formation, a pyritic siltstone–mudstone deposited in deep water, is overlain by impure limestone, diamictite (including boulders of felsic tuff possibly derived from the Depot Glen Formation of the Teltawongee Group), rippled sandstone beds and clean quartzite, that imply shallowing to a marine shelfal depositional environment. Branching to sinuous trace fossils from siltstone–sandstone interbeds of the lower Jeffreys Flat Formation in Gum Vale Gorge were inferred by Webby (1984) to be of possible Cambrian to Early Ordovician age. The Yancannia Formation is mostly mudstone or siltstone of low metamorphic grade. The Easter Monday Formation is predominantly metasandstone, metamudstone and phyllite of probable turbiditic origin (interpreted from graded bedding and Bouma sequences) with rare diamictite. A laminated felsic tuff from the Easter Monday Formation has a SHRIMP II U–Pb zircon age of 497.2 ± 2.6 Ma using the Temora standard (Black 2006, 2007), comparable to the age of an intrusion in the Bittles Tank Volcanics of the Koonenberry area.

The Evelyn Creek volcanics (informally named by Greenfield, in Greenfield et al. 2010) is an ungrouped unit comprising mafic igneous rocks of alkaline affinity that are restricted to flows, sills and dykes in the Tibooburra and Mount Poole inliers. These rocks imply protracted intraplate magmatism in three stages throughout the ‘Middle’ to Late Cambrian in the Tibooburra–Milparinka area: an initial episode coeval with deposition of the Depot Glen Formation (Teltawongee Group), followed by intrusion into this unit, and finally

extrusion coeval with the Easter Monday Formation (Warratta Group) in the Late Cambrian.

Thomson OrogenCambrian and Ordovician rocks are inferred to occupy a large area of the very poorly exposed Thomson Orogen in northwestern New South Wales (Glen et al. 2010), but data on precise ages and correlations to units in the adjacent Lachlan and Delamerian orogens are scarce. Rocks of the Warratta and Tibooburra inliers and the Yancannia Range, discussed above, may belong to the Thomson Orogen. Unnamed quartz-rich turbiditic rocks of probable Late Ordovician age (determined from poorly preserved graptolites) were intersected in Louth DH L5 drillhole. This facies contrasts with contemporaneous black shales of the Warbisco Group that are widespread in the Albury–Bega Terrane of the Lachlan Orogen (see below). Upper Ordovician sediments are unknown in the Hermidale Terrane and from the Delamerian Orogen.

Lachlan Orogen — continental margin terranesCoarse- to fine-grained sandstones and siltstones of turbiditic origin, with associated pelagic sediments of latest Cambrian to Middle Ordovician age, constitute a large part of the Lachlan Orogen. They include the Castlemaine Supergroup in Victoria, the Adaminaby Group in southeastern New South Wales and eastern Victoria (including the equivalent Pinnak Sandstone of central and southeastern Victoria), the Abercrombie Formation on the Goulburn 1: 250 000 geological map and adjacent areas, the Wagga Group in central southern New South Wales and the Girilambone Group in the central-northern part of the state. Although initially regarded as superficially similar throughout their stratigraphy (Coney 1992), these turbiditic and associated sedimentary packages can now be subdivided into five biostratigraphic zones of Early and late Middle Ordovician age using conodonts identified in thin sections of cherts (Plate 1) that occur in horizons interbedded with the sandstone-dominated units (Percival 2006a; Percival & Zhen 2007). Correlation of this conodont-based biostratigraphy (following on from pioneering studies by Stewart 1988, Stewart & Fergusson 1988, and VandenBerg & Stewart 1992 in Victoria and southeastern NSW) with the detailed graptolite zonation of the Castlemaine Group, has permitted recognition of different terranes of Ordovician age, as well as lithostratigraphic distinctions throughout the Lachlan Orogen (Glen et al. 2009). Upper Ordovician rocks of the Lachlan Orogen lack cherts and (except for the Sunbury Group in Victoria) are typically rich in black shale that contains graptolites; these rocks are included in the Bendoc Group throughout the Albury–Bega Terrane.

14 September 2011

Plate 1. A selection of biostratigraphically significant Ordovician conodonts that occur in cherts of the Lachlan Orogen in NSW. A. Oepikodus evae M element, Mummel Chert Member of Abercrombie Formation; locality AJJ 0015.02, Taralga 1:100 000 sheet. B. Oepikodus evae Sb element, Narrawa Formation; locality SJT 0270.01, Sussex 1:100 000 sheet. C. Oepikodus evae Sb element, Mummel Chert Member of Abercrombie Formation; locality AJJ 0015.02, Taralga 1:100 000 sheet. D. Oepikodus evae Sc element, Mummel Chert Member of Abercrombie Formation; locality AJJ 0015.02, Taralga 1:100 000 sheet. E. Oepikodus evae Sc element, Narrawa Formation; locality SJT 0270.01, Sussex 1:100 000 sheet. F. Oepikodus evae Sc element, Mummel Chert Member of Abercrombie Formation; locality AJJ 0015.02, Taralga 1:100 000 sheet. G. Paracordylodus gracilis S element, Narrawa Formation; locality SJT 0171.01, Sussex 1:100 000 sheet. H. Paracordylodus gracilis Sa? element, Mummel Chert Member of Abercrombie Formation; locality MMS 0104.01, Taralga 1:100 000 sheet. I. Pygodus serra Pa element, Nattery Chert Member of Abercrombie Formation; locality GLS 202, Goulburn 1:100 000 sheet. J. Periodon aculeatus Sa element, Nattery Chert Member of Abercrombie Formation; locality GLS 202, Goulburn 1:100 000 sheet. K. Periodon flabellum Pb element, Mummel Chert Member of Abercrombie Formation; locality MMS 0104.01, Taralga 1:100 000 sheet. L. Periodon flabellum Sc element, Mummel Chert Member of Abercrombie Formation; locality MMS 0104.01, Taralga 1:100 000 sheet. M. Periodon flabellum Sd element, Mummel Chert Member of Abercrombie Formation; locality ODT 0091.01, Taralga 1:100 000 sheet. N. Spinodus spinatus Sc? element, from unnamed chert (possibly Peach Tree Chert Member) in upper Abercrombie Formation; locality LJS 0179.01, Taralga 1:100 000 sheet. O. Paroistodus horridus Sb element, from unnamed chert in upper Abercrombie Formation; locality ODT 0543.01, Taralga 1:100 000 sheet. P. Periodon aculeatus conjoined (left to right) S, Pb? and possible M elements, Nattery Chert Member of Abercrombie Formation; locality LJS 331, Goulburn 1:100 000 sheet. Bar scales represent 0.1 mm. Chert sections are approximately 50 microns thick. (Photographer: D. Barnes)

Albury–Bega Terrane (Figure 5, columns 6–10)As defined by Glen et al. (2009), the Albury–Bega Terrane is an amalgamation of the Albury and Bega terranes (Glen 2005) now merged as a result of additional biostratigraphic age dating. The stratigraphy of the monotonous and extensive turbiditic sandstone sequence (Adaminaby and Wagga groups) has been compiled from widespread observations of incomplete sections. An understanding of the succession has

been complicated by imbrication of black shale, chert and turbiditic sandstone from various parts of the sequence (Glen & VandenBerg 1987; Glen et al. 1990). The turbidite sequence is punctuated by 2–3 prominent and regionally extensive chert-rich horizons of which the lowermost is more sporadic, consisting of thinly bedded cherts, sometimes interlayered with turbiditic sandstones. The cherts contain conodont faunas ranging in age from Late Cambrian (indicated by paraconodonts including Furnishina) to Early Ordovician, dominated

15Quarterly Notes

by Paracordylodus gracilis and Oepikodus evae. The Upper Cambrian cherts are correlatives in part of the Goldie Chert and Howqua Chert in Victoria, which contain species of the conodont Cordylodus of latest Cambrian (Datsonian) age (Stewart & Fergusson 1988, Kakuwa & Webb 2010). However, in Lower Ordovician rocks in Victoria, such cherts are generally absent, being replaced by a dark grey to black siliceous shale or siltstone containing graptolites Tetragraptus approximatus and Pendeograptus fruticosus (inter alia) (VandenBerg & Stewart 1992). The upper horizon comprises bedded chert up to 100 m thick that contains late Darriwilian (Pygodus serra Zone) conodonts. Graptolites are comparatively rare in turbidite sequences of Early and Middle Ordovician age in NSW. A fauna including the long-ranging Tetragraptus quadribrachiatus, found in highly cleaved slates of andalusite grade in the Narrandera district by Keble and Macpherson (1941), suggests a generalised Darriwilian age for these rocks. Jenkins (1982) also recognised mid-Darriwilian (Da2–3) graptolites in the Adaminaby Group east of Braidwood.

Above the younger chert horizon, turbidite sedimentation decreases through a transitional, commonly laminated sequence of siltstone, black shale, and sandstone with thin cross-laminated quartzitic silt layers (Glen & VandenBerg 1987; VandenBerg et al. 1991; VandenBerg et al. 2000; Glen et al. 2009). Within this transitional package, the characteristically micaceous, feldspathic and lithic, quartz-rich sandstones of the lower turbidite sequences become more mature. Subsequently, black shales of the Bendoc Group (Warbisco Shale) dominate from the earliest Late Ordovician. As the upper part of the sequence has been most comprehensively described in eastern Victoria, some discussion is included below with correlations between that region and southern NSW.

Cooma–Monaro region and eastern Victoria (Figure 5, column 6)In the Cooma–Bega–Mallacoota region, turbiditic sandstones and cherts of Early–Middle Ordovician age are attributed to the Adaminaby Group (first named by Fairbridge 1953, according to Glen 1994; current definition dates from Glen et al. 1990). Undifferentiated turbiditic rocks of the Adaminaby Group in the Monaro region of southern NSW (Glen 1994) are equivalent to the Pinnak Sandstone of eastern Victoria (VandenBerg & Stewart 1992; VandenBerg et al. 2000). No stratigraphic base to the turbidite package has been found due to the presence of internal imbrication and deformation (Glen 1995), although Late Cambrian conodonts are known from coastal outcrops in the Batemans Bay area previously assigned to the Narooma Terrane (Glen et al. 2004) but now interpreted as part of the Albury–Bega Terrane (Kakuwa & Webb 2010). Turbiditic sequences comprise green to grey–green laminated slates and siltstones interbedded with

sandstones of variable thickness. Sandstone/slate ratios and sandstone bed thicknesses vary and these have been used to locally discriminate lithofacies: Fenton et al. (1982) inferred four lithofacies in the Mallacoota area of eastern Victoria, and Powell (1983) identified proximal and distal facies from outcrops on the NSW south coast. Others working in the same region (e.g. Glen 1994) discriminated thick-bedded (>1 m), medium-bedded (>20 cm) and thin bedded (<20 cm) sandstone facies. Sandstone beds in thick-bedded facies are generally parallel-sided, contain Bouma divisions A and B, and only rarely display sole markings. Sandstone beds in thin-bedded facies are dominated by divisions B and C, with the latter containing cross-laminations, with lesser convolute laminations and flame structures. The grain size of sandstone beds in the Adaminaby Group is mostly medium or finer, and conglomerates are conspicuously absent. Mud-rich facies dominate in some areas (Glen & Wyborn 1997).

The prominent and widespread upper chert-dominated package is called the Numeralla Chert, first recognised in the Cooma region (Glen 1994; Glen & Lewis 1994). The Numeralla Chert conformably overlies the lower, turbiditic parts of the Adaminaby Group with a gradational lower contact and includes one or more mappable chert-dominated units up to 100 m thick that consist of beds of parallel-sided ribbon chert up to 50 cm thick, interbedded with cleaved slate and siltstone and rare sandstone beds. Chert beds contain recrystallised radiolarian tests as well as conodonts that were originally ascribed a Darriwilian–Gisbornian age (e.g. Glen 1994) but are now known to be of late Darriwilian (late Da3 to latest Da4) age (Percival 2006a; Percival & Zhen 2007). Although an older chert horizon has not been recognised in the Cooma–Monaro area, Oepikodus evae and Paracordylodus gracilis have been reported in chert layers within undifferentiated Adaminaby Group on the NSW far south coast (Eden area) by Stewart and Glen (1991). In eastern Victoria, both chert horizons were included in the Pinnak Sandstone (VandenBerg et al. 1991) with some Pygodus serra-bearing cherts (correlatives of the upper horizon) also reported in the Sunlight Creek Formation (Willman et al. 1999, p. 103, after VandenBerg & Stewart 1992).

Overlying the Numeralla Chert in the Cooma–Monaro region is a thin succession of interbedded sandstone, siltstone and slate forming the 300–400 m thick Chakola Formation (Glen 1994). The top 50–100 m of that unit constitutes the Glen Fergus Member (Glen 1994; Glen & Lewis 1994), distinguished by very thinly bedded mudstones and slates interbedded with thin sandstones containing broad, low-amplitude cross laminations. The sandstones within this part of the sequence are typically more mature than those below the Numeralla Chert horizon, with large quartzites lenses, although micaceous and feldspathic sandstones are also conspicuous.

16 September 2011

In far south-eastern NSW and north-eastern Victoria, rocks of the Adaminaby Group are conformably overlain by the Upper Ordovician Bendoc Group (Glen et al. 1990), which is defined primarily by conspicuous and regionally extensive graptolitic black shales with relatively minor development of sandstone. In some areas, such as east Gippsland (eastern Victoria) and west of the Cooma Metamorphic Complex (southern NSW), the basal unit of the Bendoc Group is the Sunlight Creek Formation (formerly Sunlight Creek Member of the Warbisco Shale; VandenBerg et al. 1991 after Glen et al. 1990) of Gisbornian age that consists of well-laminated black shales bearing Nemagraptus gracilis, siltstones and thin beds of sandstone. More substantial incursions of sandstone may also form part of this unit and its relationship to the Chakola Formation (here left ungrouped) requires further study.

The transition to Warbisco Shale (VandenBerg et al. 1991) by cessation of sandstone/quartzite/silt deposition, took place within the Gisbornian as indicated by the presence of Climacograptus bicornis in the lower part of this formation (Percival & Sherwin 2005). Graptolitic black shales and siltstones of the Bendoc Group typically occur as narrow, generally linear fault-bound belts with a stratigraphic thickness generally less than 400 m (VandenBerg 1981; VandenBerg et al. 1991). Accurate measurements are rarely possible since some slices have been internally imbricated or extended, illustrated locally by repetition or excision of graptolite zones (VandenBerg 1981; Glen & VandenBerg 1987). Typically, older parts of the Warbisco Shale are more siliceous, locally becoming a black chert, whereas upper parts are fissile parallel to bedding. Weathered black shales in the Michelago area south of Canberra (Richardson 1979), previously known informally as the ‘Foxlow beds’ but now referred to the Warbisco Shale (Glen, Dawson & Colquhoun 2007), contain a diverse Late Ordovician (Ea2–3) graptolite fauna (Williamson & Rickards 2006).

Above the Warbisco Shale, the base of of the turbiditic New Country Sandstone (VandenBerg et al. 1998; VandenBerg et al. 2004) is defined by the introduction of medium- to fine-grained, pale to dark grey quartz sandstone with common detrital muscovite, interbedded with subordinate black mudstone. The distribution of the unit is sporadic and it is typically viewed as a local transition to Yalmy Group or Cobbannah Group sandstones into the Early Silurian. In east Gippsland (Victoria) the New Country Sandstone is laterally equivalent to, or overlain by, the Akuna Mudstone (VandenBerg et al. 1991) of latest Ordovician (late Bolindian) age (VandenBerg et al. 1991), a unit that extends into far southern New South Wales just north of Delegate (White & Chappell 1989). Further north, in the Cooma 1:100 000 sheet area, a distinctive khaki mudrock termed the Gungoandra Siltstone (modified after Richardson 1975: Gungoandra Siltstone Member; raised to formation status by Glen et al. 1990, and

defined by Glen 1994) is reported to gradationally overlie the Warbisco Shale and hence may be a correlative of the Akuna Mudstone (Glen 1994). However, the occurrence of monograptid graptolites of late Llandovery age in the Gungoandra Siltstone on the Michelago 1:100 000 map (Sherwin, in Richardson 1979) suggests that further investigation of this unit is necessary.

Canberra–Queanbeyan region (Figure 5, column 7)Around Canberra in the ACT and eastwards to Queanbeyan in NSW, the Pittman Formation and the Acton Shale represent late Middle Ordovician and Late Ordovician rocks (both units named and defined by Öpik 1954, 1958). Öpik (1958) noted the presence of sandstone, shale and minor radiolarian chert beds (up to 6 m in thickness) in the Pittman Formation. These lithologies, together with the occurrence of graptolite faunas of two different ages listed by Öpik (1958) — one of probable late Darriwilian age and the other (about 30 m below the Acton Shale) with Gisbornian affinities — suggest that the Pittman Formation likely correlates with the uppermost part of the Adaminaby Group. Additional evidence is provided by conodonts, including Pygodus serra and Periodon aculeatus of latest Darriwilian age, that Nicoll (1980) documented from shale underlying a thin chert bed within the Pittman Formation. Graptolites identified by Öpik (1958) from the Acton Shale, of Gisbornian, Eastonian and possibly earliest Bolindian age (the latter represented by Pleurograptus linearis), support its correlation with the Warbisco Shale of the Bendoc Group (Glen, Dawson & Colquhoun 2007). Although the Acton Shale has for many years been considered a member of the Pittman Formation (cf. Strusz & Henderson 1971; Abel 1991), our preferred correlation with the Warbisco Shale implies that any sandstone-dominated sequence overlying the black shale is either a latest Ordovician New Country Sandstone equivalent, or is Early Silurian.

Sporadically intercalated within the Warbisco Shale and its correlatives are very clean sandstones, the most prominent of which is the Tidbinbilla Quartzite, a 300 m-thick lenticular unit that outcrops in the Brindabella Ranges on the western side of the ACT. The unit was originally assigned by Owen and Wyborn (1979) to the Silurian but later reassessed as Upper Ordovician (VandenBerg & Stewart 1992). Although fossils are absent from the quartzitic sandstones, we concur with Owen and Wyborn’s original supposition of a Silurian age, based on lithological similarity to sandstones of the Yalmy Group. The Tidbinbilla Quartzite was equated by Abel et al. (2008) with the Lower Silurian Black Mountain Sandstone in the Canberra region.

Goulburn region (Figure 5, column 8)Early–Middle Ordovician turbiditic rocks in the Goulburn–Taralga area (between Sydney and Canberra) are referred to as the Abercrombie Formation

17Quarterly Notes

(redefined by Thomas et al., in Thomas et al. in press, incorporating several units previously recognised on the Taralga 1:100 000 sheet by Scheibner 1973). These rocks are lithologically identical to the contemporaneous undifferentiated Adaminaby Group in which they are included. Framework grains in sandstone beds are dominated by plutonic quartz (up to 80%). Feldspar and lithic fragments are more common low in the Abercrombie Formation beneath the oldest chert beds, characterising the Willigam Sandstone Member (defined by Thomas & Scott, in Thomas et al. in press) as a quartzo-feldspathic sandstone. Stratigraphically higher sandstones are typically fine- to medium-grained and moderately sorted, occasionally grading to poorly to bimodally sorted coarse- to very coarse-grained sandstone with larger grains up to 3 mm. The main mineral components are rounded to sub-rounded grains of quartz, up to 10% detrital feldspar and ~5% detrital white mica; metasedimentary lithic fragments are rare. Trace minerals include tourmaline, apatite and zircon. The matrix to these framework grains varies from 15–40%, composed of clay and silt–mud sized quartz grains. East of Mudgee, similar sandstone is fine- to very fine-grained, framework supported (matrix 2–23%) and consists mainly of quartz (61–93%) displaying strong undulose extinction, polycrystalline metamorphic and polygonal textures, all indicating a metamorphic source, together with albite feldspar (up to 4.6%) (Colquhoun et al. 1999).

Biostratigraphic control is provided by conodonts including Oepikodus evae from the Mummel Chert Member (defined by Thomas & Scott, in Thomas et al. in press) indicative of a late Bendigonian to Chewtonian age (Percival et al. 2003). A younger chert horizon in the region north of Goulburn, named the Peach Tree Chert Member by Thomas, Pogson and Percival (in Thomas et al. in press) contains early to mid Darriwilian conodonts (Percival & Zhen 2007).

Also in the Goulburn area, thick late Middle Ordovician (late Da3–latest Da4) cherts are represented by the Nattery Chert Member of the Abercrombie Formation (the member defined by Thomas & Pogson, in Thomas et al. in press). This member correlates with the Numeralla Chert in southern NSW. Stewart and Fergusson (1995) reported cherts with the same conodont fauna (Pygodus serra) in what they referred to as Sunlight Creek Formation in the Bungonia area east of Goulburn, though more recent mapping in the region (Thomas et al. in press) now recognises these outcrops as Nattery Chert Member.

Fergusson and Fanning (2002) defined a 300 m-thick, distinctive thin-bedded turbidite sequence in the Shoalhaven Gorge area east of Goulburn as the Bumballa Formation. Those rocks consist of cross-laminated sandstones — some of which have been interpreted as contourites by Jones et al. (1993) — interbedded with shales that contain late Gisbornian

graptolites in the upper beds. Thus this unit is substantially similar to the Sunlight Creek Formation of VandenBerg et al. (1991).

In the southern half of the Goulburn 1:250 000 mapsheet, the Warbisco Shale (see above) is overlain by the Margules Group (Scott et al., in Thomas et al. in press) with three constituent formations of possible latest Ordovician or earliest Silurian age (although palaeontological evidence is lacking). The Dignams Siltstone (Thomas, in Thomas et al. in press), a silty and sandy unit 100–500 m thick that is distinguished by its olive–grey to brown colour, is confined to the Goulburn 1:100 000 mapsheet. Apparent conformable relations between the Warbisco Shale and the Dignams Siltstone suggest that the latter is likely equivalent to the Akuna Mudstone. Possibly laterally equivalent in part, and interpreted to conformably overlie the Dignams Siltstone or the Warbisco Shale elsewhere on the Taralga 1:100 000 mapsheet, is the Poidevins Sandstone (Thomas & Simpson, in Thomas et al. in press), consisting of fine to very coarse-grained quartzose sandstone with minor grey–green siltstone, at least 1200 m thick. Of comparable thickness is the turbiditic Mundoonen Sandstone (modified by Sherwin, in Thomas et al. in press, after Mundoonen Series of Sherrard 1939) that forms characteristic red, brown and orange sandstone exposures in the Mundoonen Range between Gunning and Yass. The Poidevins Sandstone (and possibly the Mundoonen Sandstone) may correlate with the Lower Silurian Cobbannah or Yalmy groups. Another interpretation (Sherwin & Strusz 2002), which we view as less likely, regards the Mundoonen Sandstone as extending from the Bolindian into the Lower Silurian.

Oberon–Rockley region (Figure 5, column 9)Considerable disparity exists in recent interpretations of the stratigraphy of Ordovician rocks found in the Oberon–Rockley region. The oldest unit in this area, indicated by presence of an Early Ordovician (late Lancefieldian to early Bendigonian) conodont assemblage dominated by Paracordylodus gracilis, is the Budhang Chert (Murray & Stewart 2001). This formation, restricted in outcrop to a single large fault-bounded block, was originally placed in the Macquarie Arc succession as a member of the Triangle Formation, but subsequently was tentatively reassigned to the Adaminaby Group by Percival and Glen (2007). The Mozart Chert, also defined by Murray and Stewart (2001) as a member of the Triangle Formation, is identical in appearance and age (based on the presence of late Darriwilian conodonts) to the widespread Numeralla Chert and equivalent facies such as the Nattery Chert Member of the Abercrombie Formation on the Goulburn 1:250 000 sheet to the south of Oberon (Thomas et al. in press), and therefore undoubtedly belongs to the Adaminaby Group. Another unit named by Murray and Stewart (2001), the Gidyen Volcanic

18 September 2011

Member, has never been formally defined and appears to represent an admixture of allochthonous debris indistinguishable from the Rockley Volcanics. The latter unit, together with the Triangle Formation, was previously assigned to the eastern belt of the Macquarie Arc (Murray & Stewart 2001; Percival & Glen 2007). The Triangle Formation consists of quartz siltstone with conglomerate, debris flow and olistostromal horizons. These rocks underlie the Rockley Volcanics, that has been assumed to consist entirely of volcaniclastic strata. However, recent work (Quinn et al. in prep) has shown that much of the Rockley Volcanics comprises quartz siltstones similar to those of the Triangle Formation. Conodonts of Gisbornian age were recovered from cherty siliceous siltstones of the Triangle Formation in Triangle Creek (Fowler & Iwata 1995), but closer inspection reveals that these cherty siltstones are clasts in younger matrix.

The greatly contrasting ages of the Mozart and Budhang cherts and their limited extent, the recognition of smaller chert blocks within a siliceous matrix in Triangle Creek, and the occurrence of Silurian fauna reported by Pickett (1973) in allochthonous? limestones mapped within the Triangle Formation (cf. Stuart-Smith & Wallace 1997) to the south, combine to suggest that a complete re-appraisal of the regional geology is necessary. One hypothesis is that these Ordovician units represent exotic blocks within a younger (Silurian–Devonian) Triangle Formation. Alternatively, the chert horizons may have been structurally imbricated with arc-related or later sediments and detached completely from the underlying and overlying turbidite strata. These observations, together with a contrasting non-magnetic and high-K geophysical signature, distinguish this sequence from other parts of the Macquarie Arc and imply that much of the sedimentary succession in the Oberon–Rockley–Triangle Creek area is of Silurian or younger age incorporating allochthonous Ordovician elements. If the presence of autochthonous strata of Ordovician age cannot be confirmed, then the basis for considering that part of the Rockley–Gulgong Volcanic Belt south of the Bathurst Batholith to be an easterly belt of the Macquarie Arc must be seriously questioned.

Forbes–Condobolin–Cargelligo region (Figure 5, column 10)The Lower to Upper Ordovician Wagga Group, consisting predominantly of quartz-rich turbiditic rocks with very minor cherts, is not well known due to poor outcrop and lack of detailed mapping, except in the Cargelligo region. Warren et al. (1995) introduced the term Wagga Group in the Cootamundra area. Hendrickx and Colquhoun (in Colquhoun et al. 2005, p. 19) noted that sequence 1 of Warren et al. (1995) most likely represents a fault-bounded slice of Bendoc Group (a contention supported by the presence of Late Ordovician graptolites in black shales), and thus it appears that the informal units recognised by Warren

et al. (1995) cannot be utilised to subdivide the Wagga Group. As now defined by Hendrickx and Colquhoun (in Colquhoun et al. 2005), the Wagga Group includes units cropping out northwest of Condobolin that were previously included in the Tallebung Group by Trigg (1987) (see Appendix).

Isolated exposures of strata assigned to the Wagga Group in the western part of the Forbes 1:250 000 geological sheet were named the Clements Formation by Duggan and Scott (in Lyons et al. 2000). Much of this formation is turbiditic, with alternating beds of quartz-rich sandstone grading to siltstone and slate. The sandstones are described by Colquhoun, Hendrickx and Meakin (in Colquhoun et al. 2005) as very fine to medium grained, mature to supermature with minor feldspar (up to 2%). Rare sedimentary and metamorphic lithic fragments are present, and the matrix contains less than 2% mica. Colquhoun et al. (2005) recorded a 10–25 m-thick lens of clast-supported conglomerate grading to pebbly sandstone, in which clasts 2–15 mm in diameter are composed of rounded to subrounded vein quartz, quartz sandstone, black chert, phyllite and rare granite. The conglomerate lens appears to be conformable with surrounding turbiditic sandstone in the upper part of the Clements Formation and therefore likely represents a contemporaneous channel fill facies (Colquhoun et al. 2005). Also present in the Clements Formation are outcrops of massive quartzite.

Two discontinuous chert horizons provide age constraints. The Milby Chert Member, named by Colquhoun, Hendrickx and Meakin (in Colquhoun et al. 2005), contains the late Bendigonian to early Castlemainian conodont Oepikodus evae. This chert occurs in the Tullibigeal area east of Lake Cargelligo (Percival et al. 2003) and also in the hanging wall of the west-dipping Gilmore Fault Zone that bounds the Wagga Group to the east. Cherts of early Darriwilian age, comparable with those recognised in the Adaminaby Group, are not presently known from the Wagga Group. A Pygodus serra–Periodon aculeatus conodont assemblage (Percival & Zhen 2007) establishes a latest Darriwilian age for the Doongala Chert Member (named by Colquhoun, Hendrickx & Meakin, in Colquhoun et al. 2005), which is estimated to be less than 10 m thick in the Ungarie area. Both cherts are relatively poorly exposed and are impersistent laterally, forming lenticular bodies which pass into sandstone, mudstone and shale of the turbiditic succession. Vertical stratigraphic relationships are similarly obscure. Late Darriwilian graptolites documented by Sherwin (1983) from isolated outcrops were previously assigned to the Tallebung Group at The Meadows Tank, 70 km southwest of Cobar (Barnato 1:250 000 sheet) and Illewong near Mt Tallebung (northwest of Condobolin), but now inferred (by Colquhoun, Hendrickx & Meakin, in Colquhoun et al. 2005, p. 31) to belong to the Clements Formation.

19Quarterly Notes

In the eastern part of the Cargelligo 1:250 000 map sheet, the most extensive unit of the Upper Ordovician Bendoc Group is the Currawalla Shale (formally defined by Colquhoun & Hendrickx, in Colquhoun et al. 2005), which occurs at or near the tops of thrust sheets and attains a thickness of ~100–200 m (not allowing for internal thrust imbrication). These black shales (equivalent to the Warbisco Shale) contain graptolites ranging in age from Gisbornian to early Bolindian (Bo1) age (Colquhoun & Hendrickx, in Colquhoun et al. 2005). The Currawalla Shale in part interfingers with, and is overlain by, a regionally extensive ~800 m thick quartz-rich sandstone-dominated unit named the Willandra Sandstone by Hendrickx and Colquhoun (in Colquhoun et al. 2005). Compared with sandstone of the older Clements Formation, the Willandra Sandstone is less mature and had a more diverse provenance, derived from a predominantly metamorphic/granitic source with possible volcanic input. According to Hendrickx and Colquhoun (in Colquhoun et al. 2005), quartz-rich sandstone which makes up the bulk of this formation is white to pale grey in colour, poorly to moderately sorted with subangular to rounded quartz and lithic grains, the latter including chert, mudstone and very fine sandstone. In contrast, the characteristic black sandstone that is distributed throughout the Willandra Sandstone is composed almost entirely of poorly sorted quartz grains of two main size groupings: 0.5 mm diameter in the matrix, surrounding larger (1–2 mm) grains. The black colour appears to be due to very fine opaque material in the matrix. Another distinctive facies (though relatively uncommon) in the Willandra Sandstone is gritty lithic sandstone of granule to conglomeratic grainsize; constituent grains include clear black quartz, inferred to be volcanic in nature, white vein quartz, together with lithic components including schist, chert and mudstone.

Black shale beds within the Willandra Sandstone contain a diverse late Eastonian to early Bolindian (Bo1–Bo2?) graptolite fauna, similar in age to that at the top of the locally underlying Currawalla Shale. Discontinuity of outcrop prevents placement of these fossiliferous levels in accurate stratigraphic relationship to the sandstone forming much of the Willandra Sandstone, and as the top of the unit is not exposed, the age of the upper beds is uncertain.

Hermidale TerraneSussex–Byrock region (Figure 5, column 11)The Girilambone Group was initially identified by Andrews (1915) as the Girilambone Series, although this excluded the Ballast Beds (now a constituent formation of the Girilambone Group). First usage of Girilambone Group in its current context was by Russell and Lewis (1965). For a historical overview of the nomenclatural history of the unit, see Pogson (1991).

The most recent revision of the Girilambone Group (Trigg & Burton, in Burton et al. in press) incorporates three formations and two members recognised in the Sussex–Byrock region northeast of Cobar. The Lower Ordovician Narrama Formation (new name, defined by Burton et al. in press) consists of thick to thin bedded quartz-rich turbiditic sandstone grading to siltstone, interbedded with thin chert horizons that contain the index conodonts Paracordylodus gracilis (spanning the late Lancefieldian to latest Chewtonian interval), and Oepikodus evae, which ranges from late Bendigonian to early Castlemainian in age (Percival 2006b, 2007a). Enclosed within the turbidite sequence of the Narrama Formation at Dijou Mountain and Bald Hills are basaltic volcanics of oceanic intraplate affinity. These include the 45 m-thick Kaiwilta Member (defined by Trigg, in Burton et al. in press), which typically has a basal basaltic/basic volcanic horizon overlain by lithic quartz sandstone and minor siltstone. The top of the unit is marked by a 1–3 m thick, laterally extensive horizon of thinly bedded chert. The Kaiwilta Member is directly overlain by the Mount Dijou Volcanic Member (described in detail by Trigg & Burton, in Burton et al. in press, after Brunker 1968) which includes amygdaloidal pillow basaltic and trachytic lavas with inter-pillow chert that contains Oepikodus evae. Felton (1981) also recorded the presence of mafic volcanics (altered vesicular basalt, in one place associated with a small patch of limestone now converted to sheared marble) apparently interbedded within the Girilambone Group on the Canbelego 1:100 000 sheet area.

The Ballast Formation was first termed the Ballast Series by Andrews (1913); subsequently it has been variously called the Ballast Chert, Beds, Group and Formation (the latter first used by Iwata et al. 1995). Burton and Trigg (in Burton et al. in press) provide the most detailed description of the Ballast Formation to date. It consists of interbedded turbiditic sandstone-dominated beds grading to siltstone and chert, as well as thick persistent packages of ribbon chert tens of metres thick. Correlatives of the latter include the Whinfell Chert Member (Felton 1981) in the Canbelego area, and Alandoon Chert on the Bobadah 1:100 000 map sheet (Pogson 1991). Very small outcrops of basaltic and other mafic rocks are present within the Ballast Formation. Burton et al. (in press) also recognised a facies variant of the Ballast Formation, which they have defined as the Lang Formation (although our preference is to include this unit as part of the Ballast Formation). Criteria used to distinguish the two units include a greater predominance of sandstone in the Lang Formation and lesser proportion of chert compared with the Ballast Formation. Rare, very weathered volcanics are known from two outcrops and a drillhole intersection in the Lang Formation. The formations were deposited contemporaneously; cherts from both yield conodonts including Pygodus serra and Periodon aculeatus,

20 September 2011

indicative of a late Darriwilian (upper Da3 to top Da4) age (Stewart & Glen 1986; Iwata et al. 1995; Percival & Zhen 2007).

Condobolin–West WyalongThe southernmost extent of Girilambone Group rocks terminates against the Cowal Igneous Complex near West Wyalong. Just north of Condobolin, the Murda Formation, defined by Scott (in Lyons et al. 2000), is characterised by magnetite-bearing massive red sandstone with minor white sandstone, siltstone and chert. Conodonts observed in the chert are long ranging, and some appear to span the Late Ordovician interval, though none provide a precise age (Percival, Palaeontological Appendix in Lyons et al. 2000).

Other formations and subdivisions of the Girilambone Group described from the exposed eastern margin of the Lachlan Orogen west of Nyngan and Tottenham include the Break O’Day Amphibolite (on the Bobadah 1:100 000 map sheet: Pogson 1991), and clastic rocks (phyllite, sandstone, quartzwacke and quartz–mica schist) from drill core in the vicinity of the Tritton copper prospect, named the Tritton Formation (Fogarty 1998) that unconformably overlies ‘basement schist’ of unknown age. Constituents of the Tottenham Subgroup on the Narromine 1:250 000 sheet including the Mount Royal Formation, Bogan Schist and Carolina Forest Formation were defined by Sherwin (1996) based on underground sections and drill core examined by Suppel (1977); these rocks are moderately strongly metamorphosed and lack fossils.

Parkes–Forbes–Junee areaPoorly exposed quartz-rich turbiditic rocks between the Junee–Narromine and Molong volcanic belts of the Macquarie Arc have been assigned to the Kirribilli Formation (Raymond & Wallace, in Lyons et al. 2000) and its possible equivalents, the Bribbaree, Bronxhome and Trigalong formations (Warren et al. 1995). Ordovician depositional ages have previously been proposed for these units by lithological correlation with either: (1) the Late Ordovician(?) to Early Silurian Cotton Formation (Krynen et al. 1990; Warren et al. 1995) or (2) Early to Middle Ordovician quartz-rich turbiditic rocks of the Lachlan Orogen, e.g. the Adaminaby, Wagga and Girilambone groups (Glen & Wyborn 1997; Meffre et al. 2007). Fossils supporting an Ordovician age for these formations are lacking or unsubstantiated, except for late Darriwilian conodonts in the Flint Hill Chert Member (of the Bribbaree Formation); however, these isolated chert units may represent a series of blocks redeposited into younger sediments (Quinn et al. in prep.). The Mugincoble Chert (Bowman et al. 1982 after Brunker 1972; Krynen et al. 1990) that forms prominent ridges in the area between Mugincoble rail siding and Parkes, also contains late Darriwilian conodonts including Periodon aculeatus and Pygodus serra (Percival 2007b; I. Stewart

& R.A. Glen unpublished data cited in Lyons & Wallace 1999). The postulated position of these chert bands in the upper Kirribilli Formation was taken by several authors (Raymond & Wallace, in Lyons et al. 2000; Lyons & Percival 2002; Meffre et al. 2007) to support an Ordovician age for the Kirribilli Formation, but the contiguity of these sediments with the cherts and their provenance are suspect. Recent age-dating of zircon grains using LA-ICPMS (Quinn et al. unpubl.) indicates a probable Silurian age for the Kirribilli Formation.

Oceanic crust and associated unitsIn the eastern Lachlan Orogen just west of the Gilmore Fault Zone near Tumut, Ordovician mafic volcanics include the Nacka Nacka Metabasic Igneous Complex which has tholeiitic chemistry and contains hornblende with K–Ar dates of ~466 Ma (Basden 1990). Near West Wyalong, mafic tholeiitic rocks are represented by the Narragudgil Volcanics (defined by Duggan, in Lyons et al. 2000). They are geochemically primitive, low K2O, with a flat rare earth element pattern and have been attributed to an ocean floor setting, either on a ridge or back arc basin (Duggan & Lyons 1999; Duggan, in Lyons et al. 2000). A minimum age is based on intrusion by the Early Silurian (433.7 ± 2.3 Ma) Bland Diorite and a suite of dykes geochemically related to the diorite (L.P. Black pers. comm., in Lyons et al. 2000, p38).

Initial descriptions of the Jindalee Group (Basden 1982, 1990; Warren et al. 1995) tentatively assigned a Cambrian? to Early Ordovician age to a disparate set of loosely associated rocks in the Tumut and Cootamundra regions that entirely lacked fossils or isotopic age dating. Subsequent discovery of conodonts (Percival 1999b) spanning a late Darriwilian to Gisbornian range in the Hoskins Chert (Lyons, Duggan & Wallace in Lyons et al. 2000) provided some age control, as did the documentation of similar late Middle to Late Ordovician conodonts including Periodon aculeatus and Pseudobelodina from chert blocks in the Jindalee Group north of Cootamundra (Lyons & Percival 2002). Rocks now assigned to the Jindalee Group occupy a discontinuous belt that extends from the Tumut area north to Narromine; they comprise a fragmented ophiolitic sequence of now-serpentinized hartzburgites and other ultramafic rocks, gabbros, pillow basalts and bedded and inter-pillow cherts, and jaspers within a younger sedimentary matrix (Quinn unpublished data). This group incorporates the Brangan Volcanics (Lyons, Duggan & Wallace, in Lyons et al. 2000) and Hoskins Chert (on the Forbes 1:250 000 Sheet, near Grenfell), the Valley View Metabasic Igneous Complex, Wermatong Metabasalt and Brungle Creek Metabasalt, and Bullawyarra Schist (all on the Tumut 1:100 000 sheet: Basden 1990), as well as some parts of the Wambidgee Serpentinite and Gundagai Serpentinite on the Tumut 1:100 000 and Cootamundra 1:250 000 sheets (Warren et al. 1995). All these units are now interpreted

21Quarterly Notes

as blocks, redeposited together with Wenlock–Ludlow limestone and rare dacite clasts, and enclosed by matrix that is no older than Ludlow–Pridoli in age (Quinn et al. unpublished data). Unnamed volcanics east of Narromine consist of pillow basalts intermixed with cherts containing late Darriwilian conodonts (Percival & Glen unpublished data) and are also included in this group, although the volcanics were too weathered for meaningful analysis.

Macquarie Arc (Figure 5, columns 12–22)The Macquarie Arc is a mineral-rich Ordovician intraoceanic island arc that was accreted to Gondwana during the Benambran Orogeny in the earliest Silurian. Ages and correlations of stratigraphic units and major volcanic packages across the Macquarie Arc have been presented recently in a detailed review by Percival and Glen (2007) as part of a synthesis of the geological evolution and metallogenesis of this region (Crawford, Glen et al. 2007), summarised below. Rocks of the Macquarie Arc occur in four belts that reflect accretion followed by dismembering during extension in the Silurian–Devonian (Glen et al. 1998). The westernmost of these, the Junee–Narromine Volcanic Belt, approximates the core of the arc, containing at least 16 discrete igneous complexes distributed over a length >200 km. These complexes are buried under younger strata and are recognised on the basis of aeromagnetic anomalies. The best known examples such as the Narromine, Cowal and Fairholme igneous complexes (described in detail by Crawford, Cooke and Fanning 2007) have been extensively drilled by mineral exploration companies. These complexes exhibit a similar history, with an initial Early Ordovician phase of basalt–andesitic lavas and volcaniclastics being intruded (after a significant hiatus) during the later Middle Ordovician and Late Ordovician (see figure 2a in Percival & Glen 2007 for details of stratigraphy). In the Narromine Igneous Complex, this intrusive phase comprises two petrographically and geochemically distinct suites, one dominated by monzodiorite with subsidiary monzonite and monzogabbro with emplacement ages between 465–460 Ma, and the other characterised by younger dacitic dykes and a granodiorite stock, averaging 445 Ma (Crawford, Cooke & Fanning 2007). A comparable history has been described for the Cowal Igneous Complex in the southern part of the Junee–Narromine Volcanic Belt. Volcanic belts further east (Molong Volcanic Belt, and the northern part of the Rockley–Gulgong Volcanic Belt) and the less well known Kiandra Volcanic Belt to the south, are largely dominated by volcaniclastic rocks that are inferred to represent parts of the arc apron.

The three main magmatic phases (plus an intrusive Phase 3) that characterise the evolution of the arc over 50 million years (Crawford, Glen et al. 2007; Crawford, Meffre et al. 2007) are best recognised in

the Junee–Narromine Volcanic Belt and the western part of the Molong Volcanic Belt where Phases 1 and 2, and Phases 2 and 4 are separated by hiatuses in arc magmatism. Phase 1 magmatism is characterised by medium to high K calc-alkaline geochemistry, with local shoshonites. Phase 1 rocks comprise andesitic and basaltic? lavas, and coarse-grained volcaniclastic rocks that grade up into finer, deepwater graptolitic siltstones of late Lancefieldian (La3) to mid Bendigonian (Be2) age (Glen, Crawford et al. 2007; Percival & Glen 2007). Monzonites with shoshonitic chemistry dated at 481 Ma mark the last stage of Phase 1 magmatism.

A hiatus in magmatism of ~9 my, accompanied by uplift and erosion of Phase 1 rocks (Percival & Glen 2007), predates Phase 2 magmatism, which is represented in all three northern volcanic belts. Phase 2 magmatism is expressed mainly by volcaniclastic lithologies, ranging in age from the early Darriwilian (Da2) to latest Gisbornian, and high/medium K calc-alkaline lavas intruded by granodiorites and diorites (Crawford, Meffre et al. 2007). In both the western and northern part of the central volcanic belt, Phase 2 lavas and volcaniclastic sediments interfinger with late Darriwilian to Gisbornian carbonate shelfal deposits (Percival & Glen 2007).

In the western part of the reconstructed Macquarie Arc, the latest Darriwilian to late Eastonian stages are characterised by a second hiatus in arc magmatism marked by growth of an extensive shallow-water carbonate platform 500 m thick over an interval of about five million years (Percival & Glen 2007). This hiatus is broadly contemporaneous with Phase 3 magmatism, represented by intrusive 451–447 Ma dacites. In the eastern, mainly volcaniclastic, part of the arc, allochthonous limestone bodies of comparable middle Eastonian age in deep water volcaniclastic sediments provide a link to the in-situ platform to the west. Phase 3 also coincides with a change in chemistry to high K shoshonitic Phase 4 magmatism. This last phase is divisible into an extrusive interval from late Eastonian (Ea4) to mid Bolindian (Bo3), and an intrusive episode in the Llandovery (Early Silurian). Products of both are shoshonitic, and contrast with the largely medium to high K calc-alkaline geochemical signature characteristic of older parts of the arc.

During second generation regional mapping programs conducted during the 1990s covering the Bathurst and Dubbo 1:250 000 map sheets, three groups of Ordovician sedimentary rocks (including volcaniclastic, clastic and carbonate strata) were defined for the Molong Volcanic Belt. The concepts of these groups changed significantly as mapping proceeded, resulting in two of these groups being incorporated into the third. As originally defined by Pogson (in Pogson & Watkins 1998), the Cabonne Group corresponded generally to rocks of magmatic Phase 4 by including all Upper Ordovician strata overlying limestones of Eastonian age. However, with subsequent

22 September 2011

inclusion of those carbonate-dominated formations (previously assigned to the now-obsolete Barrajin Group), together with mostly volcanic and volcaniclastic units of Darriwilian to Gisbornian age formerly constituting the Kenilworth Group (also now obsolete — see Appendix), the Cabonne Group as currently defined (in Thomas et al. in press) is equivalent to all volcanic and sedimentary units that comprise magmatic Phases 2 and 4, and thus correlates with the Northparkes Group of the Junee–Narromine Volcanic Belt.

Parkes–Gunningbland–Trundle area, central Junee–Narromine Volcanic Belt (Figure 5, column 12)The Nelungaloo Volcanics (Sherwin 1973; Sherwin, in Lyons et al. 2000) is the oldest formation in this region. Due to poor exposure, the nature of the contact with the overlying Yarrimbah Formation (Sherwin, in Lyons et al. 2000, modified from Sherwin et al. 1987) is unclear, but appears to be marked by a coarse conglomeratic facies at its base, suggestive of a brief erosional interval. Siliceous siltstones that form the majority of the Yarrimbah Formation contain graptolites with an age range from late Lancefieldian (La3) to mid Bendigonian (Be2) (Sherwin 1979, 1990). This formation is unconformably overlain by volcaniclastic rocks and andesitic lavas of the Goonumbla Volcanics (Sherwin 1973; Krynen et al. 1990) the concept of which has been modified several times, by Percival (in Lyons et al. 2000), Simpson et al. (2005) and Percival and Glen (2007). The Northparkes Group (originally Northparkes Volcanic Group of Percival, in Lyons et al. 2000) was established to include the Goonumbla Volcanics and correlative volcanic and sedimentary units. In the Trundle–Bogan Gate area, this group includes poorly exposed andesitic to trachyandesitic lavas, tuffs, volcaniclastic breccias and sparse fossiliferous limestones containing Eastonian corals and conodonts (Pickett & Ingpen 1990), named the Raggatt Volcanics by Sherwin (1996), that correlate with the Goonumbla Volcanics. West of Parkes in the Gunningbland district, several fossiliferous formations appear to be contemporaneous with the majority of the Goonumbla Volcanics, whereas to the north and south of Parkes, comparable sedimentary units are rare to absent (with one notable exception of a fossiliferous arkose containing late Eastonian corals) and therefore continuity of Goonumbla Volcanics is assumed from the Darriwilian to early Bolindian. Conodont data from Zhen and Pickett (2008) show that the oldest limestone lens within the basal Goonumbla Volcanics is early Darriwilian (Da2). The Billabong Creek Limestone (first named by Sherwin 1970, although its Late Ordovician age was earlier recognised by Packham 1967; redefined by Percival, in Lyons et al. 2000) is well-constrained by conodonts and coral assemblages (Pickett & Percival 2001) ranging in age from late Darriwilian (Da4) to early Eastonian (Ea2). The conformably overlying

Gunningbland Formation (Sherwin & Percival, in Lyons et al. 2000, modified from Sherwin et al. 1987) is of late Eastonian (Ea3–4) age, indicated by as yet-undescribed graptolites. This formation also contains a diverse fauna including brachiopods (Percival 1978, 1979a, 1979b), trilobites (Edgecombe & Webby 2006, 2007) and nautiloids (Percival 2009) in fine sandstones and siltstones, with corals and stromatoporoids (Webby & Morris 1976; McLean & Webby 1976) in limestone lenses. The Gunningbland Formation is presumed to be overlain by the uppermost beds of the Goonumbla Volcanics, although the contact is covered by soil. The palaeontological framework is complemented by a detailed volcanic facies analysis of the Goonumbla Volcanics and overlying Wombin Volcanics (Simpson et al. 2005). The youngest Ordovician strata in this region are siltstones (with minor chert beds) containing latest Ordovician (late Bolindian) graptolites listed by Sherwin (1970). Although Sherwin assigned these rocks to the ‘lower’ Cotton Formation that is elsewhere of Early Silurian age, thereby implying depositional continuity across the Ordovician–Silurian boundary that is unproven from any other succession in NSW, more likely these siltstones are facies equivalents of the near-contemporaneous Jingerangle Formation exposed to the southwest between Grenfell and West Wyalong.

Ordovician volcanic rocks lying east of the Parkes Thrust, that were recognised and defined by Sherwin et al. (1987) and Krynen et al. (1990), include the Parkes Volcanics (in a high-strain zone near Parkes) and Daroobalgie Volcanics (north of Forbes). The Parkes Volcanics were described by Crawford, Meffre et al. (2007) as moderately plagioclase-phyric basaltic andesites and andesites with subordinate augite phenocrysts, that are compositionally distinct from both the Early Ordovician Nelungaloo Volcanics, and the Middle to Late Ordovician Goonumbla Volcanics. Crawford, Meffre et al. (2007) interpreted geochemical affinities of the Parkes Volcanics as closer to the Cargo Volcanics and Walli Volcanics (Phase 2) of the Molong Volcanic Belt. In contrast, Crawford, Meffre et al. (2007) found that the Daroobalgie Volcanics have a shoshonitic signature comparable to the Goonumbla Volcanics, implying that this unit should not be merged with the Parkes Volcanics as proposed by Sherwin and Percival (in Lyons et al. 2000).

Marsden–West Wyalong–Temora, southern Junee–Narromine Volcanic Belt (Figure 5, column 13)Ordovician stratigraphy of the southern part of the Junee–Narromine Volcanic Belt, where exposures are few, is comparatively poorly known. Percival et al. (2006) documented a diverse conodont, coral and stromatoporoid fauna of Eastonian age from unnamed limestone intersected in exploratory drilling by Newcrest Mining Ltd in the Barmedman Creek area, south of Marsden. The Jingerangle Formation,

23Quarterly Notes

described by Warren et al. (1995) and Percival and Lyons (in Lyons et al. 2000), is exposed further southeast towards Quandialla. It is predominantly a spiculitic facies of deep water origin containing sponges, a diverse nautiloid fauna and graptolites of probable early Bolindian age (Percival et al. 2006).

Warren et al. (1995) defined and assigned Ordovician ages to several volcanic and volcaniclastic rock packages in the southmost part of the Junee–Narromine Volcanic Belt on the Cootamundra 1:250 000 geological sheet, including the Gidginbung Volcanics, Temora Volcanics, Junawarra Volcanics, and several units such as the Belimebung Volcanics, Boonabah Volcanics, Grogan Volcanics and Currumburrama Volcanics, that are only recognised in the subsurface from borehole intersections. The Gidginbung Volcanics have high K calc-alkaline to shoshonitic affinities (Glen, Spencer et al. 2007) and are overlain by limestone containing an early Llandovery conodont (Percival & Glen 2007, p. 149), so are most likely part of the Ordovician arc sequence. Although the Temora Volcanics are also shoshonitic, they are associated with sparse fossils implying a Silurian age (Warren et al. 1995). The Junawarra Volcanics are excluded by their tholeiitic geochemistry from the Macquarie Arc (Wyborn 1996) and their age is conjectural. Ordovician ages interpreted for the other volcanic units mentioned here are speculative.

Bakers Swamp–Molong, northern Molong Volcanic Belt (Figure 5, column 14)In the Bakers Swamp area, the age of the conformable boundary between the volcaniclastic Mitchell Formation (Morgan & Scott, in Meakin & Morgan 1999) and the overlying Hensleigh Siltstone (Wolf et al. 1968) is provided by an upper Prioniodus elegans conodont fauna (mid to late Bendigonian age) obtained from autochthonous limestones at the boundary, and from allochthonous limestones in the lower part of the Hensleigh Siltstone (Zhen et al. 2004a). Graptolites from the upper Hensleigh Siltstone are currently under study (Kraft, Percival, Erdtmann & Sherwin, in prep.). A sparse conodont fauna from allochthonous limestones in the lower Fairbridge Volcanics (named by Adrian 1971; described in detail by Morgan, Scott & Percival, in Meakin & Morgan 1999) suggests an early to mid-Darriwilian age (Percival et al. 1999). More precise age control is provided by conodonts from the Wahringa Limestone Member (Morgan, Percival & Scott, in Meakin & Morgan 1999), which range in age from late Darriwilian (Da4) to late Gisbornian (Gi2) (Zhen et al. 2004b). The upper beds of this unit therefore correlate with the Yuranigh Limestone Member (Scott & Pogson, in Pogson & Watkins 1998) near the top of the Fairbridge Volcanics in the vicinity of Molong. The diverse fauna dominated by brachiopods, stromatoporoids and sponges described from these

limestones (Percival et al. 2001) is — apart from one species of stromatoporoid in common — quite distinct from that in the overlying Reedy Creek Limestone (Ross 1961; Adrian 1971), and its correlative, the Cliefden Caves Limestone Subgroup to the south. A graptolite fauna from the middle of the overlying Cheesemans Creek Formation (Sherwin 1971) was revised by VandenBerg (2003), who assigned a late Eastonian to early Bolindian age.

Bowan Park, central western Molong Volcanic Belt (Figure 5, column 15)Although Morgan, Scott and Krynen (in Pogson & Watkins 1998) advocated that the term Cargo Andesite be suppressed in favour of the Fairbridge Volcanics in the Cargo–Cudal–Bowan Park area, this suggestion has been superseded by the studies of Simpson et al. (2007) and Crawford, Meffre et al. (2007), who have shown that the Cargo Volcanics is distinct geochemically from the Fairbridge Volcanics. Hence the name Cargo Volcanics (modified after Stevens 1950) is reinstated for the succession of lavas and volcaniclastics that are overlain unconformably by the Bowan Park Limestone Subgroup (modified after Stevens 1957) of the Cabonne Group. The highly fossiliferous limestone contains conodont faunas, described by Zhen et al. (1999), that range in age from the Taoqupognathus philipi conodont Zone (early Eastonian, Ea1) in the lower Daylesford Limestone (described and subdivided into multiple members by Semeniuk 1970, 1973) at the base of the Bowan Park succession, through the T. blandus conodont Zone in the Quondong Limestone (Semeniuk 1970, 1973), and into the T. tumidus Zone (late Eastonian, Ea3–4) within the Downderry Limestone Member of the Ballingoole Limestone (Semeniuk 1970, 1973) at the top of the subgroup and also in limestone clasts within the basal part of the overlying Malachis Hill Formation (Stevens 1957). Higher in the latter formation, about 300 m above siltstones with an undescribed early Bolindian (Bo2?) graptolite fauna, limestone pods of probable allochthonous origin contain a diverse coral assemblage (Fauna IV of McLean & Webby 1976) believed to be of mid–late Bolindian (Bo3–4?) age (Percival & Glen 2007).

Belubula River valley, south of ‘Canomodine’, south-western Molong Volcanic Belt (Figure 5, column 16)The Cargo Volcanics in this area remained exhumed longer than at Bowan Park to the north, as carbonate deposits, represented by the Canomodine Limestone (Stevens 1950) (including the synonymous Cargo Creek Limestone) did not accumulate until Eastonian 2 time, extending into the late Eastonian (Ea3). The age is based on coral and stromatoporoid faunas (Webby 1969); due to the sheared nature of the limestone, conodonts have not been obtained. The Canomodine Limestone is overlain by the Rockdale Formation (Ryall 1966), a succession of siltstones of probable latest Eastonian

24 September 2011

to early Bolindian age (graptolites identified by Ryall would suggest a Gisbornian age, but the limited fauna requires revision) that is equivalent to the lower part of the Malachis Hill Formation. The youngest unit in this area, assigned a latest Ordovician age (although palaeontological evidence is lacking), is the Millambri Formation (modified by Ryall 1966, from the usage of Stevens 1957 to include only the upper turbiditic sand-dominated part of his original Millambri Formation), composed of volcaniclastic sandstone and conglomerate containing clasts of andesitic volcanics.

Cliefden Caves area, southeastern Molong Volcanic Belt (Figure 5, column 17)The Kenyu Formation (Stevens 1955), a volcanic and volcaniclastic unit in the southern-most part of the Molong Volcanic Belt, has recently been determined to be as young as latest Gisbornian in age (Percival et al. 2008), based on conodonts from an allochthonous limestone block in its upper part. This age suggests a minimal hiatus between the top of the correlative Walli Volcanics (modified by Krynen & Pogson, in Pogson & Watkins 1998, after Stevens 1952) in the Cliefden Caves area and the disconformably overlying Cliefden Caves Limestone Subgroup (modified by Krynen & Pogson, in Pogson & Watkins 1998, after Stevens 1952). Three formations (the lowermost with multiple members) have been described by Webby and Packham (1982) from this limestone: the well-bedded Fossil Hill Limestone at the base, overlain by the massive-bedded Belubula Limestone, in turn overlain by the Vandon Limestone. Conodonts obtained throughout these limestones are of early Eastonian (Ea1–2) age (Zhen & Webby 1995), correlative with the Daylesford Limestone to Quondong Limestone succession of the Bowan Park Limestone Subgroup. Many papers have been published over the past forty years (mainly by Webby, Percival and colleagues) describing the diverse fossil assemblages of trilobites, brachiopods, rugose and tabulate corals, stromatoporoids and sponges in the Cliefden Caves Limestone Subgroup and their depositional environments (see references listed in Webby 1992). Siltstones and spiculites of the overlying Malongulli Formation (Stevens 1952) contain diagnostic graptolite faunas close to its base (Ea3) and top (Bo1) (Percival 1976), and its Late Ordovician age is also is constrained by conodonts found in allochthonous deep-water sponge-bearing limestones in its lower part (Trotter & Webby 1995). Mid Bolindian (Bo3) graptolites (Jenkins 1978) are present in several siltstone horizons in the overlying volcaniclastic-dominated Angullong Formation (Krynen & Pogson, in Pogson & Watkins 1998, after Stevens 1952) but to date, no age-diagnostic conodonts have been found in allochthonous limestones that are sporadically encountered in this unit.

Cadia–Panuara area (Figure 5, column 18)Between Panuara (southwest of Cadia mine) and the

Belubula River, the Ordovician stratigraphy contrasts markedly with that of the Cliefden Caves area to the southwest, owing to separation by a major thrust fault. The oldest unit recognised in the Cadiangullong Creek valley is the Weemalla Formation (name formalised by Wyborn, Krynen & Pogson, in Pogson & Watkins 1998, after unpublished thesis mapping by J. Taylor) which contains an undescribed Darriwilian (Da3) graptolite fauna (Smith 1966), as well as calcareous mudstone beds yielding conodonts of Da2 age (Zhen & Percival 2004b). Andesitic volcanics and volcaniclastic strata conformably overlying the Weemalla Formation in the vicinity of Cadia are named the Forest Reefs Volcanics (defined by Wyborn, in Pogson & Watkins 1998), for which the only internal age control is provided by Late Ordovician (Eastonian, Ea3) conodonts from thin beds of altered limestone in its upper part (Packham et al. 1999). The Forest Reefs Volcanics beneath these limestone interbeds is therefore contemporaneous with the Walli Volcanics and the Cliefden Caves Limestone Subgroup (Percival & Glen 2007), although there is no evidence of concurrent eruptive volcanism in the latter above the middle of the Fossil Hill Limestone Member. To explain the absence of volcanic detritus in the Cliefden Caves Limestone Subgroup (and in correlative formations such as the Regans Creek Limestone along strike to the north), Packham et al. (1999) put forward the hypothesis that the Eastern Province of the Molong Volcanic Belt (where Middle and Late Ordovician volcanism was concentrated) was not juxtaposed with the carbonate-dominated Western Province until the latest Ordovician to earliest Silurian.

Forest Reefs–Junction Reefs–Blayney area (Figure 5, column 19)Several different interpretations of stratigraphic relationships in this area have been proposed in recent years (see discussion in Zhen & Percival 2004b). The following summary follows the views of Percival and Glen (2007) and Crawford, Glen et al. (2007). The Coombing Formation (modified by Wyborn, in Pogson & Watkins 1998, from the description of Wyborn 1992, to encompass only feldspathic mudstone that is commonly silicified and grades to fine-grained volcaniclastic sandstone) is the oldest unit recognised. Age constraints on the Coombing Formation are limited and of poor quality. Crawford, Meffre et al. (2007) derived a weighted mean age of 467 ± 4 Ma from a highly distributed and discordant set of analyses (MSWD = 3.2, probability of fit = 0.000, n = 19) obtained by laser ablation ICP-MS U/Pb analyses of detrital zircons, to imply an early Darriwilian volcanic source. Additionally, a few poorly preserved graptolites of probable late Darriwilian to Gisbornian age are known from the Junction Reefs area. In the vicinity of Forest Reefs, the Coombing Formation is overlain by the Forest Reefs Volcanics (discussed above), with the first appearance of

25Quarterly Notes

pyroxene-phyric lavas occurring just beneath the Mount Pleasant Basalt Member. The latter was previously attributed to the Weemalla Formation by Wyborn (in Pogson & Watkins 1998), but as noted by Percival and Glen (2007), based on stratigraphic revisions by Zhen and Percival (2004b), the Weemalla Formation is not present in the Forest Reefs area east of the Wongalong Fault.

In the Blayney region further east, the Coombing Formation is overlain by a thick succession predominately composed of basalt and basaltic andesite, that was subdivided by Crawford, Meffre et al. (2007) on petrographic and geochemical grounds into the lower and upper Blayney Volcanics, the Byng Volcanics, and the Millthorpe Volcanics. Age control is restricted to the occurrence of poorly preserved conodonts from recrystallised limestone known as the Cowriga Limestone Member (of the upper Blayney Volcanics) exposed at the Browns Creek mine; these conodonts were attributed a Late Ordovician age by B. Nicoll (pers. comm. to Wyborn & Krynen, in Pogson & Watkins 1998). The Blayney Volcanics (described by Wyborn, in Pogson & Watkins 1998) has a clinopyroxene-phyric and olivine-phyric lower part, and a plagioclase-phyric upper part (Crawford, Meffre et al. 2007). The original definition and distribution of the Byng Volcanics (Scott, in Pogson & Watkins 1998), was modified by Crawford, Meffre et al. (2007) to include only primitive basalts associated with ultramafic cumulates, that are interpreted on the basis of their shoshonitic affinities to be comagmatic with the upper Blayney Volcanics. Crawford, Meffre et al. (2007) distinguished other volcaniclastic rocks with evolved basaltic to basaltic andesite lavas, previously also included in the Byng Volcanics, as the Millthorpe Volcanics. This formation appears to lie above the level of the Cowriga Limestone Member in the upper Blayney Volcanics and therefore may represent Phase 4 magmatism in this area, east of Orange.

Northeastern margin of Molong Volcanic Belt (Figure 5, column 20)In its original type area, between Neurea and Dripstone, southeast of Wellington, the Oakdale Formation (Strusz 1960) includes volcaniclastic conglomeratic facies deposited as mass flows, turbiditic sandstone, and siltstone with Eastonian graptolites. All evidence points to the Oakdale Formation being deposited on a slope setting along the (present-day) northeastern margin of the Molong Volcanic Belt. Autochthonous deep-water carbonate rocks containing early Eastonian conodonts at ‘Barham Winchester’, 10 km northeast of Molong, are also assignable to the Oakdale Formation, as are comparable limestones in the Bakers Swamp area (sample C1432 in Percival et al. 1999). Webby (1973, 1974) described rare deep-water trilobites of Gisbornian age from the Neurea area. The oldest fauna from the Oakdale Formation are conodonts of late Darriwilian (Da3) age, in allochthonous limestones from the Bell

River valley northwest of Euchareena (Zhen & Percival 2004a), but the age of the enclosing matrix is presently unknown. Detailed mapping is necessary to adequately characterise this formation, which seems to constitute an amalgamation of facies and ages.

Cumnock north to Ponto, west of the Catombal RangeRecent mapping and palaeontological discoveries in the Ponto–Bournewood area west and southwest of Wellington (Percival & Quinn 2011) have resulted in substantial revision of the stratigraphy of this region. Rocks previously referred to the western outcrop belt of the Oakdale Formation (Percival et al. 1999, figures 1 & 4) have been reinterpreted as allochthonous blocks of Late Ordovician age within probable Silurian matrix in the Arthurville area. In the vicinity of the former Gunners Dam mine along strike to the south, strata informally named the ‘Gunnars Dam beds’ by Percival and Glen (2007) are now regarded as blocks of cherty spiculitic and graptolitic siltstone of Late Ordovician age emplaced into the Lower Silurian Kabadah Formation. Allochthonous Late Ordovician limestone clasts, redeposited into the Upper Silurian Barnby Hills Shale, have previously been documented from the Eurimbla area, northeast of Cumnock (Zhen, Percival & Farrell 2003). Similarly, several large limestone lenses of Late Ordovician age mapped as an unnamed member within the Sourges Shale in the vicinity of Cumnock (Percival et al. 1999, figure 5) — the southernmost one of early Eastonian (Ea1) age and of very shallow water aspect, whereas those to the north on a markedly different trend are significantly younger (Ea3) and contain a deeper water fauna — are now regarded as allochthonous blocks enclosed within sediments of known Llandovery age. This confirms that the Sourges Shale is a Silurian formation within the Cudal Group, as foreshadowed by Morgan (in Meakin & Morgan 1999). Thus, according to this new interpretation (Percival & Quinn 2011), autochthonous strata of Ordovician age are no longer recognised in the belt extending from Cumnock to Ponto, west of the Catombal Range.

Sofala–Mudgee, northern Rockley–Gulgong Volcanic Belt (Figure 5, column 21)Along the eastern margin of the Hill End Trough, in a belt extending southwards from Dunedoo to Rylstone, strata included in the Cabonne Group are the Coomber, Burranah and Tucklan formations. The Coomber Formation (Pemberton et al. 1994; Colquhoun & Meakin, in Meakin & Morgan 1999) lacks fossils, but is assigned a Late Ordovician age based on interpreted conformable contacts with underlying Adaminaby Group rocks that include chert bearing Pygodus serra of late Darriwilian age (Stewart & Fergusson 1995). Fergusson and Colquhoun (1996) described a variety of facies from the Coomber Formation, including massive lithic sandstone, thin-bedded sandstone and

26 September 2011

mudstone, siliceous or cherty mudstone, together with scattered allochthonous limestone blocks, and sporadic basalt flows and shallow intrusions. The Burranah Formation (described by Watkins, in Meakin & Morgan 1999), and to a lesser extent, the Tucklan Formation (redefined by Colquhoun, Meakin & Henderson, in Meakin & Morgan 1999) consists of mass-flow deposits, conglomerates, and minor allochthonous limestones that provide the only fossil-based age constraints on these units (Percival 1999a). An Ordovician age was ascribed to these formations based in part on their high potassium response on ternary U–K–Th radioelement imagery (typical of Ordovician rocks in the Macquarie Arc), but indiscriminate application of this criterion has led to incorrect assumptions elsewhere, e.g. in the case of the Kabadah Formation. It is conceivable that the Burranah and Tucklan rocks were originally deposited in the Late Ordovician, but were subsequently reworked into Silurian deposits of the Hill End Trough. Further south along the eastern margin of the Hill End Trough, allochthonous limestone blocks of late Eastonian age (comparable to those in the Burranah and Tucklan formations) have also been recognised (Pickett 1978; Percival 1999a) in a thick succession mapped as Sofala Volcanics, first described in detail by Packham (1968b) from the Turon River valley. Predominant lithologies in the Sofala Volcanics include volcaniclastic conglomerates, sandstones and siltstones of possible deep water turbiditic origin, with pyroxene-rich andesites and basaltic andesites in the Sofala region that in some cases may represent eruptive centres (Packham 1968b; Watkins, in Pogson & Watkins 1998). Chert is present throughout the formation, in places forming locally extensive massive to thick-bedded bands particularly prominent in the lower part. Although radiolaria and sponge spicules occur in the chert, no conodonts have yet been found. The age range of this formation is based on rare, poorly preserved graptolites that remain unillustrated; one species of possible late Darriwilian to Gisbornian age was recorded by Packham (1968b, p. 115), and another fauna was assigned a mid Bolindian age by Fons VandenBerg (cited in Rickards et al. 1998). Ar–Ar ages of 438.5 ± 0.8 Ma and 439.9 ± 0.8 Ma for monzonite and diorite that intrude the Sofala Volcanics (Perkins et al. 1995) provide minimum earliest Silurian ages for deposition of this formation.

Kiandra Volcanic Belt (Figure 5, column 22)As defined by Owen and Wyborn (1979), the Kiandra Group comprised the Temperance Formation, Nine Mile Volcanics and Gooandra Volcanics. New mapping currently underway by Quinn (unpublished data) suggests that a significant reassessment of this stratigraphy is warranted. The Temperance Formation consists of a bedded chert sequence of late Darriwilian age (indicated by presence of the conodont Pygodus sp.) with thin mafic volcaniclastic layers become

progressively more dominant up section. It is overlain by the Nine Mile Volcanics which is a finer grained sequence with black shale that contains late Gisbornian graptolites and volcaniclastic laminations (Sherrard 1954, after Öpik 1952). Rare blocks of limestone yielding the Late Ordovician conodont Belodina and a solitary rugose coral have been reported from isolated localities in the Nine Mile Volcanics near Peppercorn Creek (Owen & Wyborn 1979). Such limestones contrast with the generally deep-water character of the Kiandra Group and are unlikely to be in-situ. The Gooandra Volcanics occurs within this upper part of the sequence and is of limited extent around Gooandra Homestead, with much of the mapped area previously attributed to this formation comprising either volcaniclastic rocks (i.e. on Long Plain), siliceous siltstone-dominated strata with volcaniclastic debris flows, gritstones and conglomerates (in the Mt Selwyn to Three Mile Dam area) or siliceous siltstones with interbedded quartz sandstones and turbidite sequences (Geehi River, Mt Jagungal–Grey Mare areas) (Quinn et al., in prep.). The southern extent of the Kiandra Volcanic Belt in north-east Victoria (Allen 1988; Orth et al. 1995) is represented by the Blueys Creek Formation that includes the Brumby Mafic Arenite Member and Banksia Chert Member; the latter is characterised by black chert layers containing the conodonts Periodon aculeatus, P. cf. grandis and Belodina sp. (I.R. Stewart, in Allen 1988) indicating a Gisbornian age.

Narooma Terrane (Figure 5, column 23)The areally restricted Narooma Terrane on the NSW south coast consists of an apparently continuous succession of Late Cambrian to Late Ordovician oceanic sedimentary rocks deposited on the palaeo-Pacific plate as it drifted towards the east Gondwana margin (Glen et al. 2004). In its type area around Narooma, the Narooma Terrane comprises the Wagonga Group (modified from Wagonga Series of Browne 1949, first named and defined as Wagonga Group by Glen 1994), consisting of the Narooma Chert and the overlying argillaceous Bogolo Formation. In the revision of the stratigraphic nomenclature by Glen et al. (2004), the Kianga Basalt (established by Glen 1994) was eliminated; it was previously interpreted to underlie the Narooma Chert. The lower part of the Narooma Chert (defined by Glen 1994) consists of ribbon chert containing conodonts (illustrated in Glen et al. 2004) that range in age from Late Cambrian to Darriwilian–Gisbornian. Chert beds in the upper Narooma Chert are extensively bioturbated with Planolites tubes (Kakuwa & Webb 2010) and alternate with shale and siltstone beds that contain Eastonian graptolites. Where not deformed by later faulting, the Narooma Chert passes gradationally upwards into the Bogolo Formation (defined by Wilson 1969, modified by Glen et al. 2004), which consists of

27Quarterly Notes

argillite, conglomerate with blocks of basalt, chert and sandstone beds in an argillaceous matrix. Although undated by fossils, this formation is presumed to be of Bolindian age on the basis of its stratigraphic relationship to the underlying Narooma Chert and the presence of derived chert clasts of a wide size range.

Outcrops of the terrane 100 km to the north, extending along the coast from Batemans Bay to Burrewarra Point, have a less well defined stratigraphy, containing blocks of ‘Middle’ and Late Cambrian limestone in basaltic breccia (Bischoff & Prendergast 1987; Prendergast 2007). One clast of a limestone coquina from the southern side of Burrewarra Point yielded a diverse microfauna characterised by abundant molluscs, indeterminate agnostid trilobite remains, lingulate brachiopods, and rare conodonts including Furnishina furnishi. A ‘Middle’ Cambrian (no older than basal Undillan, i.e. late Drumian) age is postulated for this limestone (Bischoff & Prendergast 1987). Overlying black shales assigned to the upper part of the Wagonga Beds (now Group) by Jenkins et al. (1982) contain graptolite faunas at two levels, the older one of mid-Eastonian (Ea2–3) age and the younger fauna of early Bolindian age. Most likely these black shales correlate with the upper part of the Narooma Chert.

New England Orogen

Tamworth Belt (Figure 5, column 24)The oldest rocks in the Tamworth Belt, of ‘Middle’ Cambrian to early Late Cambrian age, are localised immediately west of the Peel Fault in the Copes Creek area, southeast of Tamworth. The succession commences with the Murrawong Creek Formation (Cawood 1983; Leitch & Cawood 1987), being at least 450 m thick above a faulted contact, and consisting largely of volcaniclastic sandstones interbedded with conglomeratic units. The lowermost of these, designated unit 1, is 65 m thick and is dominated by coarse-grained allochthonous limestone blocks yielding a diverse shelly fauna of late ‘Middle’ Cambrian age (Undillan–Boomerangian, P. punctuosus to L. laevigata trilobite zones). Fossils described from this level include a possible cnidarian (Engelbretsen 1993), lingulate brachiopods (Engelbretsen 1996), molluscs (Brock 1998a) possible rhynchonelliformean brachiopods (Brock 1998b, 1999) and trilobites (Cawood 1976, Sloan & Laurie 2004). Unit 2 (20 m thick) in the middle of the Murrawong Creek Formation, and unit 3 occupying the uppermost 80 m of the formation, are characterised by fine non-fossiliferous conglomerates. Palaeontological evidence supporting essentially contemporaneous deposition of the allochthonous limestone blocks of unit 1 with the enclosing sediments is provided by the conformably overlying Pipeclay Creek Formation, named by Crook (1961), who assigned an Early Devonian age. Chert beds in the formation are

now known to be of ‘Middle’ Cambrian to early Late Cambrian age based on the presence of paraconodonts and absence of euconodonts (Stewart 1995). Hence the age of the Pipeclay Creek Formation effectively constrains the age of deposition of the underlying Murrawong Creek Formation to that of the limestone clasts found in conglomerates of unit 1. Lithologies in the Pipeclay Creek Formation consist predominantly of siltstone and mudstone with subsidiary chert, tuff, sandstone and fine-grained conglomerate, more than 900 m in total thickness (Bradley, in Pickett 1982; Cawood 1983; Leitch & Cawood 1987).

Unconformably overlying the Cambrian sedimentary rocks is the Haedon Formation (Cawood 1983) that includes sandstones and boulder conglomerates with clasts comprising limestone, mudstone, basalt and andesite. Autochthonous massive and bedded limestones are intercalated with the conglomerates (Furey-Greig 2003a). Maximum thickness is estimated to be 100 m. The Middle Ordovician (Darriwilian) age obtained for this formation from conodonts (including Ansella jemtlandica, Oistodus lanceolatus, and Periodon aculeatus) and the gastropod Macluritella sp. (Cawood 1976; Furey-Greig 2003a) may be further refined to Da2–3 on the basis of fragmentary specimens of conodonts resembling Appalachignathus, Juanognathus? and possibly Periodon macrodentatus.

Packham (1969, p. 231) reported the Early Ordovician (Bendigonian) graptolite Didymograptus cf. D. minutus (currently under study by Kraft, Percival, Erdtmann & Sherwin) from an isolated outcrop of clastic sediments associated with the ‘Trelawney beds’. Limestones forming the latter unit are now regarded as allochthonous blocks of Late Ordovician age emplaced in the Drik Drik Formation (with a depositional age of Early Devonian: Emsian) (see Furey-Greig 2000b pp. 133–134). Corals (Webby 1988) and conodonts (Furey-Greig 2000b) from these allochthonous blocks are of Eastonian age. The Drik Drik Formation unconformably overlies the Haedon Formation, with the unconformity surface marked by the sudden appearance of red sandstone (Crook 1961; Cawood 1983; Furey-Greig 2003a) and basal conglomerates containing limestone clasts yielding Ordovician conodonts.

Dunmore Terrane of Central BlockThe Wisemans Arm Formation of Leitch and Cawood (1980) sensu Furey-Greig (1999, 2003b), in the Manilla region north of Tamworth previously included what were interpreted as olistoliths of limestones and laminated fine-grained feldspathic sandstones. Brown (2009) reinterpreted these blocks as fault-bounded, and assigned them to a unit he named the Glen Bell Formation, incorporating the ‘Uralba Beds’ of Hall 1975 (see Appendix for details). Possibly equivalent rocks in the Bingara 1:100 000 sheet to the north have been referred to the Dinoga Formation (Aitchison et al. 1988;

28 September 2011

Barclay et al. 1999). These rocks occur immediately east of the Peel Fault, in what is presumed to represent the subduction complex in front of the magmatic arc (Leitch & Cawood 1980). Allochthonous limestone blocks within the Glen Bell Formation contain macro- and microfaunas of two distinct ages: Late Ordovician (Eastonian), and Early Silurian (late Llandovery to early Wenlock). Depositional age of the Glen Bell Formation matrix must therefore be no older than Early Silurian, so strictly speaking this is not an Ordovician unit (and therefore is not shown on Figure 5). However, it demonstrates that Late Ordovician limestones were either once present in the Dunmore Terrane, or else they were deposited on the palaeo-Pacific plate and now lie in the Dunmore Terrane due to accumulation in the subduction complex. Evidence for the Late Ordovician clast age is indicated by the presence of conodonts of Eastonian, most likely Ea3, age (Furey-Greig 1999, 2000a, 2003b; Pickett & Furey-Grieg 2000), and corals of comparable or very slightly younger age (perhaps Ea3–4) (Hall 1975; Webby 1988).

Port Macquarie Block (Figure 5, column 25)The Port Macquarie Serpentinite, defined by Och, Leitch and Caprarelli (2007), consists of massive and schistose serpentinite together with rodingite (highly altered mafic rocks, possibly originally dykes). The serpentinite body is undated, although the ultramafic protolith is interpreted to be possibly as old as Early Cambrian on the basis of correlation with comparable serpentinised ultramafic rocks of the Woodsreef Melange in the southern New England Orogen, dated at 530 Ma by Aitchison and Ireland (1995) using zircons from plagiogranite blocks. At Rocky Beach, the serpentinite encloses two small bodies of chlorite–actinolite schist containing blocks of high pressure metamorphic rocks including blueschist and lawsonite eclogite. These exposures were named the Rocky Beach Metamorphic Melange (Och et al. 2003). They are undated, but are believed to be of similar age to the surrounding serpentinite.

The serpentinite body is surrounded by the Watonga Formation (Och, Leitch & Caprarelli 2007), that is well exposed along the coastline immediately south of Port Macquarie where it comprises mostly broken formation inferred to result from disruption of a once-stratified sequence of basalt, chert, siliceous mudstone, siltstone, sandstone and conglomerate. Conodonts visible in thin sections of cherts establish a maximum age range for these rocks extending from late Darriwilian to possibly as young as the end of the Eastonian (Och, Percival & Leitch 2007).

SynthesisThis review highlights the considerable advances in understanding of Cambrian and Ordovician

stratigraphy that have taken place in NSW over the past three decades, although much more work needs to be done — particularly in areas such as the Kiandra Volcanic Belt and the various serpentinite belts — before relationships between terranes are adequately defined. Placing all Cambrian and Ordovician rocks known from NSW in the context of a unified timescale reveals some interesting patterns which provide a key to interpreting the tectonic evolution of the region over this time interval. Comparable facies in Middle and Upper Ordovician turbidite successions that are widespread in south-eastern Australia have in the past been given different names in NSW and Victoria. As these can now be shown to be identical in age and appearance, and exhibit reasonable continuity in the field, we argue that they should be referred to the same unit. This process is already underway with rocks of the Bendoc Group being recognised throughout the Tasmanides of south-eastern Australia. Adopting a common name (such as Numeralla Chert) for the generally thick-bedded chert of late Darriwilian age at or near the top of the Adaminaby Group would clarify much of the stratigraphy of the turbidite successions. However, distinguishing the ages of these Ordovician cherts is critical. At least five distinct conodont-based zones, extending from late Tremadocian to latest Darriwilian, can be recognised in cherts in the Adaminaby Group and correlatives. If mapped on lithology alone, these cherts could readily be mis-correlated, but when different units are discriminated on the basis of conodont zones (though contrary to the Australian Code of Stratigraphic Nomenclature), more accurate mapping results.

The new and revised correlations presented here are of fundamental importance to biogeographic analyses that have widespread applicability in constraining tectonic reconstructions. For example, ‘Middle’ Cambrian limestones are known in NSW from three widely separated localities. The Murrawong Creek Formation (New England Orogen) has rhynchonelliform brachiopod faunas (Brock 1998a, b), for example, that share strong affinities at genus, but not species, level with the somewhat younger First Discovery Limestone Member of the Coonigan Formation in the Delamerian Orogen. Also micromolluscan faunas in these two formations reveal three species in common, but these similarities appear to be outweighed by differences in the remainder of the fossil assemblages. In comparing faunal elements between different offshore terranes, Engelbretsen (1993) identified two species of acrotretide brachiopods common to both the Murrawong Creek Formation faunas (Undillan–Boomerangian, P. punctuosus to L. laevigata trilobite zones) and those from ‘Middle’ Cambrian limestone clasts at Batemans Bay (basal Undillan or younger) associated with the Narooma Terrane. Both these widely separated occurrences can therefore be interpreted as essentially contemporaneous, representing faunas inhabiting

29Quarterly Notes

shallow water environments of near-emergent seamounts in the palaeo-Pacific Ocean that were relatively remote from assemblages that were to develop slightly later on the Delamerian continental margin, thereby explaining the subtle biogeographic signatures distinguishing these faunas.

Finally, the dynamism of geological processes during the Early Palaeozoic evolution of the Lachlan and New England orogens is readily appreciable from this review, highlighting the numerous examples of Ordovician rocks that have been entirely eroded from their original depositional settings, leaving only their records as allochthonous blocks within younger strata. Recognition of such occurrences of lost stratigraphy, which often depends on palaeontological discrepancies between clasts and matrix, has significantly increased over the past decade given the greater precision and widespread use of conodont age-determinations combined with careful field observations.

AcknowledgementsWe are grateful to our colleagues in the Geological Survey of New South Wales engaged in regional mapping programs in the Lachlan, New England and Delamerian orogens during the past decade, who have reappraised or described many of the stratigraphic units reviewed in this paper, and acknowledge their contributions — some of which are in press at the time of publication of this review. Gary Colquhoun supplied data on distribution of Cambrian and Ordovician strata in the state as the basis for Figures 1 and 2. David Barnes assisted with photography of conodonts in chert sections and compilation of Plate 1. Cartographic and editorial expertise was provided by Cheryl Hormann, Carey Martin, Geneve Cox and Simone Meakin. The Australian Stratigraphic Names database administered by Geoscience Australia and accessible via their website, proved invaluable in searching for references to some obscure units. We particularly thank Barry Webby for his perceptive review of the original manuscript that has significantly improved the published version.

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Cambrian–Ordovician boundary in Australia, New Zealand, and Antarctica. In: M.G. Bassett & W.T. Dean eds. The Cambrian–Ordovician boundary: sections, fossil distributions, and correlations, pp. 211–227. National Museum of Wales, Geological Series No. 3, Cardiff.Shergold J.H., Jago J.B., Cooper R.A. & Laurie J.R. 1985. The Cambrian System in Australia, Antarctica and New Zealand. International Union of Geological Sciences, Publication No. 19.Sherrard K.M. 1939. The general geology of the district east of Yass, N.S.W. Proceedings of the Linnean Society of New South Wales 64, 577–600. Sherrard K.M. 1954. The assemblages of Ordovician graptolites in New South Wales. Journal and Proceedings of the Royal Society of New South Wales 87, 73–101.Sherwin L. 1970. Age of the Billabong Creek Limestone. Quarterly Notes of the Geological Survey of New South Wales 1, 1–3.Sherwin L. 1971. Stratigraphy of the Cheesemans Creek district, New South Wales. Records of the Geological Survey of New South Wales 13, 199–237.Sherwin L. 1973. Stratigraphy of the Forbes–Bogan Gate District. Records of the Geological Survey of New South Wales 15, 47–101.Sherwin L. 1979. Age of the Nelungaloo Volcanics, near Parkes. Quarterly Notesof the Geological Survey of New South Wales 35, 15–18.Sherwin L. 1983. New occurrences of Ordovician graptolites from central New South Wales. Quarterly Notes of the Geological Survey of New South Wales 53, 1–4.Sherwin L. 1990. Early Ordovician graptolite from the Peak Hill District. Quarterly Notes of the Geological Survey of New South Wales 90, 1–4.Sherwin L. 1996. Narromine 1:250 000 Geological Sheet SI/55-3: Explanatory Notes. Geological Survey of New South Wales, Sydney.Sherwin L., Clarke I. & Krynen J.P. 1987. Revision of stratigraphic units in the Forbes–Parkes–Tomingley district. Quarterly Notes of the Geological Survey of New South Wales 67, 1–23.Sherwin L. & Strusz D.L. 2002. Dating the Mundoonen Sandstone. First International Palaeontological Congress (IPC2002), Macquarie University. Geological Society of Australia Abstracts 68, 273–274.Simpson C.J., Cas R.A.F. & Arundell M.C. 2005. Volcanic evolution of a long-lived Ordovician island-arc province in the Parkes region of the Lachlan Fold Belt, southeastern Australia. Australian Journal of Earth Sciences 52, 863–886.Simpson C.J., Crawford A.J. & Scott R.J. 2007. Volcanology, geochemistry and structure of the Ordovician Cargo Volcanics in the Cargo–Walli region, central New South Wales. Australian Journal of Earth Sciences 54, 315–352.

Sloan T.R. & Laurie J.R. 2004. Middle Cambrian trilobites from allochthonous blocks in the Murrawong Creek Formation, N.S.W. Memoirs of the Association of Australasian Palaeontologists 30, 193–206.Smith R.E. 1966. The geology of Mandurama–Panuara. Journal and Proceedings of the Royal Society of New South Wales 98, 239–262.Stait B. & Laurie J. 1985. Ordovician nautiloids of central Australia, with a revision of Madiganella Teichert & Glenister. BMR Journal of Australian Geology & Geophysics 9, 261–266.Stevens B.P.J., Mills K.J., Direen N.J., Buckley P.M. & Cooper I. 2002. Koonenberry 1:250 000 Pre-Permian Interpretation Map (2nd ed.). Geological Survey of New South Wales, Sydney.Stevens N.C. 1950. The geology of the Canowindra district, NSW. Part 1. The stratigraphy and structure of the Cargo–Toogong district. Journal and Proceedings of the Royal Society of New South Wales 82, 319–337.Stevens N.C. 1952. Ordovician stratigraphy at Cliefden Caves, near Mandurama, New South Wales. Proceedings of the Linnean Society of New South Wales 77, 114–120.Stevens N.C. 1955. The petrology of the northern part of the Wyangala Bathylith. Proceedings of the Linnean Society of New South Wales 80, 84–96. Stevens N.C. 1957. Further notes on Ordovician formations of central New South Wales. Journal and Proceedings of the Royal Society of New South Wales 90, 44–50.Stewart I.R. 1988. Conodonts. In: J.G. Douglas & J.A. Ferguson eds. Geology of Victoria. Geological Society of Australia Special Publication 5, 79–81.Stewart I.R. 1995. Cambrian age for the Pipeclay Creek Formation, Tamworth Belt, northern New South Wales. Courier Forschungsinstitut Senckenberg 182, 565–566.Stewart I.R. & Fergusson C.L. 1988. A Lower to Middle Ordovician age for the Hotham Group, Eastern Victoria. Proceedings of the Royal Society of Victoria 100, 15–20.Stewart I.R. & Fergusson C.L. 1995. Ordovician conodonts from the Lue beds, Mudgee and Sunlight Creek Formation, Goulburn, New South Wales. Memoirs of the Association of Australasian Palaeontologists 18, 164.Stewart I.R. & Glen R.A. 1986. An Ordovician age for part of the Girilambone Group at Yanda Creek, east of Cobar. Quarterly Notes of the Geological Survey of New South Wales 64, 23–25.Stewart I.R. & Glen R.A. 1991. New Cambrian and Early Ordovician ages from the New South Wales south coast. Quarterly Notes of the Geological Survey of New South Wales 85, 1–8.Strusz D.L. 1960. The geology of the parish of Mumbil, near Wellington N.S.W. Journal and Proceedings of the Royal Society of New South Wales 93, 127–136.

37Quarterly Notes

Strusz D.L. & Henderson G.A.M. 1971. Canberra City A.C.T. 1:50,000 geological map and explanatory notes. Bureau of Mineral Resources, Geology & Geophysics, Canberra.Stuart-Smith P. & Wallace D. 1997. Oberon 1:100 000 geological map 8830. Australian Geological Survey Organisation, Canberra and Geological Survey of New South Wales, Sydney.Suppel D.W. 1977. Copper deposits in the Girilambone Beds, Tottenham, New South Wales. Geological Survey Report GS1977/300. Geological Survey of New South Wales.Talent J.A. & Mawson R. 1999. North-eastern Molong Arch and adjacent Hill End Trough (Eastern Australia): Mid-Palaeozoic conodont data and implications. In: R. Feist, J.A. Talent & A. Daurer eds. North Gondwana: Mid-Paleozoic Terranes, Stratigraphy and Biota. Abhandlungen der Geologischen Bundesanstalt 54, 49–105. Thomas O.D., Pogson D.J., Simpson C., Sherwin L., Scott M.M. & Johnston A. in press. Geology of the Goulburn, 1:250 000 sheet: Explanatory Notes. Geological Survey of New South Wales, Maitland.Thomas O.D., Scott M.M., Warren A.Y.E. & Sherwin L. 2001. Gunning 1:100 000 Geological Sheet 8728, provisional. Geological Survey of New South Wales, Orange.Trigg S.J. 1987. Geology of the Kilparney 1:100,000 Sheet 8132: Explanatory Notes. Geological Survey of New South Wales, Sydney. Trotter J.A. & Webby B.D. 1995. Upper Ordovician conodonts from the Malongulli Formation, Cliefden Caves area, central New South Wales. AGSO Journal of Australian Geology & Geophysics 15, 475–499.VandenBerg A.H.M. 1981. A complete Ordovician graptolitic sequence at Mountain Creek near Deddick, eastern Victoria. Geological Survey of Victoria, Report 1981/81.VandenBerg A.H.M. 2003. Discussion of ‘Gisbornian (Caradoc) graptolites from New South Wales, Australia: systematics, biostratigraphy and evolution’ by B. Rickards, L. Sherwin and P. Williamson. Geological Journal 38, 175–179.VandenBerg A.H.M. & Cooper R.A. 1992. The Ordovician graptolite sequence of Australasia. Alcheringa 16, 33–85.VandenBerg A.H.M., Hendrickx M.A., Willman C.E., Magart A.P.M., Simons B.A. & Ryan S.M. 1998. Benambra 1:100 000 map area geological report. Geological Survey of Victoria Report 114.VandenBerg A.H.M., Nott R.J. & Glen R.A. 1991. Bendoc 1:100,000 Map Geological Report. Geological Survey of Victoria, Report 90. VandenBerg A.H.M. & Stewart I.R. 1992. Ordovician terranes of southeastern Lachlan Fold Belt: stratigraphy, structure and palaeogeographic reconstruction.

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Zhen Y.-y., Nicoll R.S., Percival I.G., Hamedi M.A. & Stewart I. 2001. Rhipidognathid conodonts from Australia and Iran. Journal of Paleontology 75, 186–207. Zhen Y.-y. & Percival I.G. 2004a. Middle Ordovician (Darriwilian) conodonts from allochthonous limestones in the Oakdale Formation of central New South Wales. Alcheringa 28, 77–111.Zhen Y.-y. & Percival I.G. 2004b. Darriwilian (Middle Ordovician) conodonts from the Weemalla Formation, south of Orange, New South Wales. Memoirs of the Association of Australasian Palaeontologists 30, 153–178.Zhen Y.-y. & Percival I.G. 2006. Late Cambrian–Early Ordovician conodont faunas from the Koonenberry Belt of western New South Wales. Memoirs of the Association of Australasian Palaeontologists 32, 267–285.Zhen Y.-y., Percival I.G. & Farrell J.R. 2003. Late Ordovician allochthonous limestones in Late Silurian Barnby Hills Shale, central western New South Wales. Proceedings of the Linnean Society of New South Wales 124, 29–51.Zhen Y.-y., Percival I.G. & Webby B.D. 2003. Early Ordovician conodonts from far western New South Wales, Australia. Records of the Australian Museum 55, 169–220.Zhen Y.-y., Percival I.G. & Webby B.D. 2004a. Early Ordovician (Bendigonian) conodonts from central New South Wales, Australia. Courier Forschungsinstitut Senckenberg 245, 39–73.Zhen Y.-y., Percival I.G. & Webby B.D. 2004b. Conodont faunas from the Mid to Late Ordovician boundary interval of the Wahringa Limestone Member (Fairbridge Volcanics), central New South Wales. Proceedings of the Linnean Society of New South Wales 125, 141–164.Zhen Y.-y. & Pickett J.W. 2008. Ordovician (Early Darriwilian) conodonts and sponges from west of Parkes, central New South Wales. Proceedings of the Linnean Society of New South Wales 129, 57–82.Zhen Y.-Y. & Webby B.D. 1995. Upper Ordovician conodonts from the Cliefden Caves Limestone Group, central New South Wales, Australia. Courier Forschungsinstitut Senckenberg 182, 265–305.Zhen Y.-Y., Webby B.D. & Barnes C.R. 1999. Upper Ordovician conodonts from the Bowan Park succession, central New South Wales, Australia. Geobios 32, 73–104.Zhuravlev A.Yu. & Gravestock D.I. 1994. Archaeocyaths from Yorke Peninsula, South Australia and archaeocyathan Early Cambrian zonation. Alcheringa 18, 1–54.

Proceedings of the Royal Society of New South Wales 109, 125–135.Webby B.D. & Packham G.H. 1982. Stratigraphy and regional setting of the Cliefden Caves Limestone Group (Late Ordovician), central-western New South Wales. Journal of the Geological Society of Australia 29, 297–317.Webby B.D., VandenBerg A.H.M, Cooper R.A., Banks M.R., Burrett C.F., Henderson R.A., Clarkson P.D., Hughes C.P., Laurie J., Stait B., Thomson M.R.A. & Webers G.F. 1981. The Ordovician System in Australia, New Zealand and Antarctica. Correlation Chart and Explanatory Notes. International Union of Geological Sciences, Publication No. 6.Webby B.D., Wang Q. & Mills K.J. 1988. Upper Cambrian and basal Ordovician trilobites from western New South Wales. Palaeontology 31, 905–938.White A.J.R. & Chappell B.W. 1989. Geology of the Numbla 1:100,000 Sheet 8624. Geological Survey of New South Wales, Sydney.Williamson P.L. & Rickards R.B. 2006. Eastonian (Upper Ordovician) graptolites from Michelago, near Canberra. Proceedings of the Linnean Society of New South Wales 127, 133–156.Willman C., Morand V.J., Haydon S.J. & Carney C. 1999. Omeo map and geological report. Geological Survey of Victoria, Report 118.Wilson C.J.L. 1969. The geology of the Narooma area, N.S.W. Journal and Proceedings of the Royal Society of New South Wales 101, 279–316.Wolf K.H., Flugel E. & Kemezys K.J. 1968. Ordovician calcareous algae from a bioherm, Blathery Creek Volcanics, New South Wales (Australia). Review of Palaeobotany and Palynology 6, 147–153.Wopfner H. 1967 [imprint 1966]. Cambro-Ordovician sediments from the north-eastern margin of the Frome Embayment (Mt. Arrowsmith, N.S.W.). Journal and Proceedings of the Royal Society of New South Wales 100, 163–177.Wyborn D. 1992. Stratigraphy and geochemistry of Ordovician volcanics from the Lachlan Fold Belt in central New South Wales. In: B.D. Webby & J.R. Laurie eds. Global Perspectives on Ordovician Geology. pp. 495–497. Balkema, Rotterdam.Wyborn D. 1996. Geology, chemistry and gold/copper potential of the Temora belt and adjacent Gilmore Fault System. In: Magmatic and hydrothermal evolution of intrusive-related gold deposits in eastern Australia. AMIRA project P425.Young G.C. 2009. An Ordovician vertebrate from western New South Wales, with comments on Cambro-Ordovician vertebrate distribution patterns. Alcheringa 33, 79–89.

39Quarterly Notes

Kenilworth Group (Pogson, in Pogson & Watkins 1998): now subsumed within the Cabonne Group (Pogson, in Pogson & Watkins 1998) as a result of reassessment of stratigraphic relationships on the Dubbo 1:250 000 sheet (Meakin & Morgan 1999) and Goulburn 1:250 000 sheet (Thomas et al. in press).

Kianga Basalt: now invalid, reinterpreted as blocks of basalt within the Bogolo Formation overlying the Narooma Chert (Glen et al. 2004).

Malay Creek Formation: shown on provisional 1st edition of Gunning 1:100 000 geological map (Thomas et al. 2001), this interbedded sandstone and black shale unit occupies an identical stratigraphic position to the Sunlight Creek Formation, hence it is redundant.

Merrere Conglomerate Member: formalised by Scheibner and Basden (1998, p. 414) as a member of the Ballast Formation, this unit is now regarded as a basal conglomerate of the Siluro-Devonian Cobar Supergroup (Glen et al. 2010).

Paddys Creek beds: part of Palgamurtie Subgroup (obsolete) in the legend to the 2nd edition Koonenberry 1:250 000 pre-Permian interpretation map (Stevens et al. 2002); as discussed by Buckley (2001), probably a thrust repeat of what is now called the Grasmere Formation, hence obsolete.

Palgamurtie Subgroup (of Ponto Group): only previously briefly described in map legends to preliminary versions of the Koonenberry pre-Permian interpretation map (Stevens et al. 2002); now obsolete.

Tallebung Group: Colquhoun, Hendrickx and Meakin (in Colquhoun et al. 2005, p. 30) recommended suppression of the name Tallebung Group as the concept of that unit (Trigg 1987) appeared to include strata of both Early to Middle Ordovician age (Wagga Group equivalents) and Late Ordovician age, indicated by the presence of probable Eastonian graptolites.

‘Trelawney Beds’ (Philip 1966; Webby 1988): comprises clasts, predominantly limestone of Late Ordovician (Eastonian age), in the Early Devonian Drik Drik Formation of Crook (1961).

‘Uralba Beds’ (Hall 1975, Webby 1988, Furey-Greig 2000a): clasts, predominantly limestone of Late Ordovician and Early Silurian age, incorporated into Wisemans Arm Formation sensu Furey-Greig (2003b), now part of Glen Bell Formation (Brown 2009).

Wonominta Beds (Warris 1967): includes rocks now variously assigned by Greenfield et al. (2010) to the Grey Range Group (of Neoproterozoic age), and Ponto, Warratta and Kayrunnera groups, and is therefore not equivalent to the Wonnaminta Formation.

AppendixObsolete, redundant and rejected names for Cambrian and Ordovician units in NSWBaroorangee Creek Subgroup (of Ponto Group): briefly described by Buckley (2001) and in the legend to the 2nd edition Koonenberry 1:250 000 pre-Permian interpretation map (Stevens et al. 2002) – now Baroorangee Creek Formation.

Barrajin Group (Morgan, in Pogson & Watkins 1998): now subsumed within the Cabonne Group (Pogson, in Pogson & Watkins 1998) as a result of reassessment of stratigraphic relationships on the Dubbo 1:250 000 sheet (Meakin & Morgan 1999) and Goulburn 1:250 000 sheet (Thomas et al. in press).

Beacons Hill Chert: distribution was shown on provisional 1st editions of the Crookwell, Boorowa and Yass 1:100 000 geological maps, but this unit is now regarded as an equivalent of the Nattery Chert Member of the Abercrombie Formation, and is therefore redundant.

Belah beds (of Ponto Group): part of Palgamurtie Subgroup (obsolete) in the legend to the 2nd edition Koonenberry 1:250 000 pre-Permian interpretation map (Stevens et al. 2002).

Bendee beds (of Ponto Group): part of Palgamurtie Subgroup (obsolete) in the legend to the 2nd edition Koonenberry 1:250 000 pre-Permian interpretation map – now assigned to Grasmere Formation (Greenfield et al. 2010).

Blue Rock Well Basalt, Blue Rock Well Phyllite, Blue Rock Well Sandstone, Blue Rock Formation (of Ponto Group): all previously part of Noonthorangee Subgroup (obsolete) in legend to Koonenberry Pre-Permian Interpretation Map (Stevens et al. 2002) – now included in Noonthorangee Formation (Greenfield et al. 2010).

Budgery Sandstone Member (of Girilambone Group): a heavily altered quartzite, mentioned in the legend of the Cobar 1:250 000 metallogenic map (Gilligan et al. 1994), but never defined. Obsolete.

Gum Creek Basalt (of Ponto Group): part of Noonthorangee Subgroup (obsolete) in the legend to the 2nd edition Koonenberry 1:250 000 pre-Permian interpretation map (Stevens et al. 2002) – now included in Noonthorangee Formation (Greenfield et al. 2010).

Humbug Sandstone (Duggan & Scott, in Lyons et al. 2000): this name for thick-bedded sandstone and quartzite facies within the Wagga Group on the Forbes 1:250 000 sheet has now been suppressed in favour of an expanded definition of the Clements Formation (Hendrickx & Colquhoun, in Colquhoun et al. 2005).

DELAMERIAN OROGEN LACHLAN OROGENNAROOMA TERRANE

NEW ENGLAND OROGENLOWER

SILURIAN

KOONENBERRY BELT ALBURY–BEGA TERRANE HERMIDALE TERRANE MACQUARIE ARC

CHEWT.

Mt. Wright–Mutawintji

Mt. Arrowsmith Kayrunnera–Koonenberry region Bilpa–Comarto, Scropes Range

Warratta + Tibooburra inliers

Cooma−Mallacoota region

Goulburn region Cargelligo Sussex–Byrock Junee–Narromine Marsden–West Wyalong– Temora

Nth Molong Volcanic Belt

Bowan Park South of ‘Canomodine’

Cliefden Caves Cadia Forest Reefs– Junction Reefs

Blayney NE Molong Volcanic Belt

Sofala–Dunedoo–Mudgee

Kiandra Volcanic Belt Narooma Tamworth–Nemingha Port Macquarie

1 2 3 4 5 6 7 8 10 11 12 13 15 16 18 19 20 22 2524232117149

Canberra–Queanbeyan

Oberon–Rockley

HIRN.

442

445

460

463

466

505

502

499

496

493

490

487

484

481

478

475

469

472

457

454

451

448

520

517

514

511

508

442

445

460

463

466

505

502

499

496

493

490

487

484

481

478

475

469

472

457

454

451

448

520

517

514

511

508

Million years

?? ?

KATI

AN

SAN

DBI

AND

ARR

IWIL

IAN

DA

PIN

- G

IAN

FLO

IAN

TREM

AD

OCI

AN

BOLI

ND

IAN

EAST

ON

IAN

GIS

BORN

IAN

DA

RRIW

ILIA

N

YAPEEN- IAN

CASTLE-MAIN-

IAN

BEN

DIG

O-

NIA

NLA

NCE

FIEL

DIA

N

WAREN-DIAN

DATSON.PAYNTON.

Bo 5 Bo 4

C A

M B

R I

A N

O R

DO

V I

C I

A N

‘SE

RIE

S 2

’M

IDD

LE

LO

WE

RU

PP

ER

‘SE

RIE

S 3

’F

UR

ON

GIA

N

DRUM- IAN

Stage 4

Stage 3

IVER

IAN

IDA

-M

EAN

MINDY-ALLANBOOM.UNDILL.FLORAN.TEMPLE-TONIAN

ORDIAN

Bo 3

Bo 2Bo 1Ea 3–4

Ea 2

Ea 1

Gi 2

Gi 1

Da 4

Da 3

Da 2Da 1Ya 2Ya 1Ca 3–4Ca 2

Ca 1

Ch 1–2Be 2–4

Be 1

La 3La 2b

La 2a

La 1b

La 1a

TOYO

NIA

N

Stage 10

Stage 9

PAIBIAN

Stage 7

Stage 5

BOTO-MAN

ATDAB- ANIAN

Rowena Formation

Gundara Quartzite Member

Bynguano Quartzite

Nootumbulla Sandstone

Nuchea Conglomerate

Coonigan Formation

Cymbric Vale

Formation

Mount Wright

Volcanics

Wyarra Shale

Wydjah Fm.

Pincally Fm.

Kandie Tank Lst.

Funeral Creek Lst.

Cupala Creek Formation

Hummock Fm.Williams Creek Conglomerate

Ponto Group

Teltawongee Group

Copper Mine

Range Fm.

Pingbilly Fm.

Tabita Fm.

Yandaminta Quartzite

Watties Bore Formation

Boshy Formation

Morden Fm.

Scropes Range

Formation

Nuchea Congl.

Bilpa Conglomerate

War

ratt

a G

roup

Gna

lta

Gro

upM

utaw

intj

i Gro

up

Pim

bill

a Ta

nk G

roup

Wheeney Creek Fm.

Kayr

unne

ra G

roup

Weinteriga Ck Fm. Grasmere Fm.

Noonthorangee Fm. Koonenberry Fm. Yandenberry Fm.

Cannela Fm. Baroorangee Ck Fm.

Wonnaminta Fm. Nundora Fm.

Bunker Ck Fm. Depot Glen Fm.

Easter Monday

Fm.Jeffreys Flat Fm.

Yancannia Fm.

Figure 5. Correlation of selected Cambrian and Ordovician rock units within New South Wales. As well as showing in-situ formations, we indicate (with broad arrows) the formerstratigraphic positions of allochthonous blocks, now redeposited into younger sediments, toillustrate a ‘ghost’ stratigraphy important to elucidating the geological evolution of the state.Units that are predominantly carbonate (limestone and dolostone) are shown in blue, and chert in tan.

Abbreviations: UNDILL. = UndillanBOOM. = BoomerangianPAYNTON. = PayntonianDATSON. = DatsonianCHEWT. = ChewtonianHIRN. = HirnantianFm. = FormationLst. = LimestoneCongl. = ConglomerateGFM = Glen Fergus MemberMbr = MemberVolc Mbr = Volcanic MemberYuranigh L M = Yuranigh Limestone MemberDL, QL, & Bal (in Bowan Park Limestone Subgroup) = Daylesford Limestone, Quondong Limestone, and Ballingoole Limestone, respectivelyFH, Bel, & VL (in Cliefden Caves Limestone Subgroup) = Fossil Hill Limestone, Belubula Limestone, and Vandon Limestone, respectively(Vic) = (Victoria); "Trelaw." = "Trelawney"

???

?

?

?

?

???

?

te

Clements Formation

Abercrombie Formation

Dignams Siltstone

Warbisco Shale

Bumballa Formation

Nattery Chert

Member

Peach Tree Chert

Member

Mummel Chert

Member

Willigam Sandstone

Member

Willandra Sandstone

Currawalla Shale

Doongala Chert

Member

Milby Chert Member

Chakola Formation

Akuna Mudstone

Warbisco Shale

Numeralla Chert

Adaminaby Group

undifferentiated

GFM

Bend

oc

Gro

up

Bend

oc

Gro

up

Sunlight Ck Formation

Ada

min

aby

Gro

up

Wag

ga G

roup

Bend

oc

Gro

up

Bend

oc

Gro

upActon Shale

Pittman Formation

Mozart Chert

Budhang Chert

Ada

min

aby

Gro

up

Margules Group

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

Ballast Formation

Mt. Dijou Volc Mbr

Kaiwilta Mbr

Narrama Formation

Giri

lam

bon

e G

roup

Whinfell Chert

Member

? ?

Bogolo Formation

Narooma Chert

(upper)

Nar

oom

a C

hert

(low

er)

Clasts at Burrewarra

Point

Wag

onga

Gro

up

?

Jingerangle FormationWombin Volcanics

Gunningbland Fm.

Billa

bon

g C

reek

Lim

esto

ne

Goo

num

bla

Vol

cani

cs

Yarrimbah Formation

Nelungaloo Volcanics

Cheesemans Creek

Formation

Reedy Creek Limestone

Yuranigh L. M.

Fairb

ridge

Vol

cani

cs

Hensleigh Siltstone

Mitchell Formation

Malachis Hill Formation

Car

go V

olca

nics

Angullong Formation

Malongulli Formation

Wal

li Vo

lcan

ics

Forest Reefs Volcanics

Weemalla Formation

Clasts of Da3

limestone

Oakdale Formation

Burranah clasts

Sofala Volcanics

Parkes Volcanics

Daroobalgie Volcanics

DL

BaL

Bowan Park LimestoneSubgroup

QL Cliefden Caves

Limestone Subgroup

FHL

BeL

VL

Kenyu Fm.?

Wahringa Limestone Member

Nine Mile Volcanics

Temperance Formation

Blueys Creek Fm. (Vic)

Gooandra Volcanics

Kian

dra

Gro

up

Millambri Formation

Rockdale Formation

Canomodine Limestone Forest Reefs

Volcanics

Coombing Formation

Mt Pleasant Basalt Member

Upper Blayney

Volcanics

Millthorpe Volcanics

Lower Blayney

Volcanics

Coombing Formation

Byng Volcanics

Jingerangle Formation

unnamed limestone at Barmedman

Car

go V

olca

nics

Coomber Formation

Adaminaby Group

?

? ? ?

? ? ?

? ?

? ? ?

? ? ?

? ? ?

?

?

?

?

?

Nor

thp

arke

s G

roup

? ? ?

? ? ?? ? ?

? ? ? ? ? ?

? ? ? ? ? ? ? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?

? ? ?? ? ?

? ? ?

? ? ?? ? ?

Cab

onne

Gro

up

? ? ?

Cab

onne

Gro

up

?

?

Haedon Formation

Pipeclay Creek Formation

Murrawong Creek Fm.

Watonga Formation

Port Macquarie Serpentinite

Rocky Beach Metamorphic

Melange

“Trelaw. Beds” clasts

Glen Bell Fm.

“Trelawney arenite”

? ? ?

?

?

? ? ?

? ? ?

Quarterly notesFuture papers:‘Early Permian shell fossils of the Hunter Valley, New South Wales’ by N.S. Meakin, L. Sherwin, P.A. Flitcroft and I.G. Percival

NSW Trade & Investment, Division of Resources & Energy 516 High Street, Maitland NSW 2320 PO Box 344 Hunter Region Mail Centre NSW 2310. T: 1300 736 122 T: (02) 4931 6666

www.dpi.nsw.gov.au 1068

3 0

9/20

11

***

101 1. Preliminary Palaeozoic bedrock interpretation of the Narromine and Nyngan 1:250 000 sheet areas 2. Palaeontology of drill hole DM Northern Parkes DDH 3102 Stratigraphy, structure and mineralisation of the Mudgee 1:100 000 geological map sheet103 Mineral deposits of the Glen Innes 1:100 000 map sheet area104 1. Geology of the Cargelligo and Narrandera map sheet areas: removing the cover using Discovery 2000 geophysics 2. Geology and sand resources of the Stockton Bight–Port Stephens area 105 A re-appraisal of the Darling Basin Devonion sequence 106 A comparative study: Calc-silicate ellipsoids from Broken Hill and diagenetic carbonate concretions from the Sydney Basin 107 1. Controls on opal localisation in the White Cliffs area 2. The age of the Nandilyan and Narragal limestones, Molong high, Central Western New South Wales 108 1. Late Ordovician biostratigraphy of the northern Rockley–Gulgong volcanic belt 2. Ordovician stratigraphy of the northern Molong volcanic belt: new facts and figures 109 DIGS — Digital Imaging of Geological System, an interactive database for the mineral industry110 Age constraints on strata enclosing the Cadia and Junction Reefs ore deposits of central New South Wales, and tectonic

implications111 Peel Discovery 2000 Geophysics — providing keys to exploration in the western New England region of New South Wales112 An internet information delivery vehicle for the resources industry — DIGS on the Net113 Volcanic Textures in the Palaeoproterozoic Hores Gneiss, Broken Hill, Australia114 Peel South Exploration NSW geophysics — interpretation of new data for exploration and geological investigations in the western

New England area of New South Wales115 New geochronology from the Coolah–Mendooran area: evidence for Middle Jurassic erosion in the southern Surat Basin116 Mineral deposits and models, Cootamundra 1:250 000 map sheet area117 1. Definition of the Brawlin Formation, Cootamundra area, New South Wales 2. Sulphur and lead isotope studies for the Cargelligo 1:250 000 map sheet area118 Murray–Riverina region: an interpretation of bedrock Palaeozoic geology based on geophysical data119 The Willyama Supergroup in the Nardoo and Mount Woowoolahra Inliers120 40Ar/39Ar geochronology of the Tara intrusion-related base metal deposit: implications for metallogenesis in the central Lachlan

Orogen121 Inverell Exploration NSW geophysics — new data for exploration and geological investigations in the northern New England area

of New South Wales122 The Fox Tor Diorite, a newly recognised intrusion within the New England Batholith, northern New South Wales123 Cainozoic igneous rocks in the Bingara to Inverell area, northeastern New South Wales124 Evaluation of mineral resources of the continental shelf, New South Wales125 A Middle Triassic age for felsic intrusions and associated mineralisation in the Doradilla prospect area, New South Wales126 Geological units of the Port Macquarie–Tacking Point tract, north-eastern Port Macquarie Block, Mid North Coast region of New

South Wales127 Volcanic arc-type rocks beneath cover 35 km to the northeast of Bourke128 Mineral Systems and Processes in New South Wales: a project to enhance understanding and assist exploration129 Deep structure beneath the Murray Basin from teleseismic tomography130 The Siluro-Devonian geological time scale: a critical review and interim revision131 The newly defined Glen Bell Formation, and a reappraisal of the Wisemans Arm Formation, Halls Creek district, northern NSW132 Mineral systems of the Murray Basin, New South Wales133 Contrasting age and isotope characteristics of volcanic-hosted and skarn-type mineralisation near The Glen, Goulburn, in the

Lachlan Orogen, New South Wales134 A revised Triassic stratigraphy for the Lorne Basin, NSW135 Phoenix: an Early Devonian granite-related tungsten deposit from the eastern Lachlan Orogen, New South Wales136 Fossil microbes in opal from Lightning Ridge — implications for the formation of opal

Index of Quarterly Notes from 101 to 136Available on DIGS: http://digsopen.minerals.nsw.gov.au.