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Dr Rian Dutch – Geological Survey of South Australia
A collaborative effort between:
LIFTING THE LID ON THE COOMPANA
PROVINCE
GEOLOGICAL SURVEY OF SOUTH AUSTRALIA
Geoscience for the Benefit of South Australians
• Part of the Mineral Resources Division of the South Australian
Department of the Premier and Cabinet.
• Our role is to undertake pre-competitive data acquisition and value-
add research to provide scientific information on the State's geology
and resource potential.
• Key role in investment attraction by reducing exploration risk and
creating a knowledge rich environment to increase the chance of
discovery.
The Coompana Province is a rare opportunity• Covers an area of approximately
200 000 km2, straddling the border
between South Australia and
Western Australia
• No known exposed basement rocks
of the Coompana Province, with the
region being extensively covered by
basin sediments
• No serious mineral exploration for
more than 30 years
• Existing datasets are dated and
coarse scale
COOMPANA PROVINCE: AN UNEXPLORED FRONTIER
Musgrave Province
Yilgarn Craton
Gawler Craton
Coompana Province
A WORKFLOW TO DISCOVERY
QUESTION – what are the key datasets and knowledge that will
provide a framework for discovery in this region
• Depth of cover
• Structural framework and fluid pathways
• Mapping basement under cover (distribution and rock properties)
• Tectonic and crustal evolution (geodynamic setting)
A WORKFLOW TO DISCOVERY
McCuaig & Hronsky, 2014.
Taking a mineral systems approach• Identify magmatic systems. These provide the
driving force for much of the worlds mineral
systems
• Identify crustal fertility and map out
architecture and pathways
• Identify the regional geodynamic setting of
events to assist explorers in applying the correct
exploration models and strategies
A WORKFLOW TO DISCOVERY
The second step – New pre-competitive data acquisition
To date ~$7.5M committed or expended PACE pre-competitive data collection
• $1.7M 13GA-EG1 seismic line
• $50K Pilot regional biogeochemistry
• $1.3M Coompana magnetics and radiometrics
• $500K AusLAMP ($240K from Geoscience Australia)
• $20K + collaborative funding Coompana cover geophysics
• $1.0M Coompana regional gravity
• $3M Coompana regional drilling
• $500K Regional soil geochemical survey
NEW DATA AQUISITIONEucla Gawler seismic and MT
NEW DATA AQUISITIONCoompana Regional Magnetic Survey
NEW DATA AQUISITIONAusLAMP Magnetotellurics
10 km 35 km
NEW DATA AQUISITIONCover geophysics
• Passive Seismic
• Reflection Seismic
• AMT
• Micro-gravity
70 65 60 55 50 45 40 35 30 25 20 15 10 5 -0
De
pth
(m)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230
Distance (m)
S-wave velocity cross-section : Line ID=CP04
(m/s)
S-wave velocity
10001100120013001400150016001700180019002000
Scale = 1/1000
NEW DATA AQUISITIONRegional Gravity - Previous
NEW DATA AQUISITIONRegional Gravity - New
NEW DATA AQUISITIONCoompana Drilling Program
• $3M collaborative program
Between GSSA and GA
• Up to 18 bores
• Targeting different
geophysical domains
• Boart Longyear selected
as drilling service provider
• Drilling commenced 9th
April 2017 for ~ 5 month
program
NEW DATA AQUISITIONCoompana Drilling Program
First look at
core from
CDP001
Basement at 346m
Currently 164m
HQ3 core
Mixture of foliated
dioritic gneiss and
undeformed
granitoids
A WORKFLOW TO DISCOVERY
QUESTION – what are the key datasets and knowledge that will
provide a framework for discovery in this region
• Depth of cover
• Structural framework and fluid pathways
• Mapping basement under cover (distribution and rock properties)
• Tectonic and crustal evolution (geodynamic setting)
DEPTH OF COVERDepth to magnetic source
• Work by Clive Foss
(CSIRO)
• Individual magnetic
depth estimates based
on multiple inversions
of individual anomalies
• Gridded data to produce
both a map and surface
DEPTH OF COVERDepth to magnetic sourceDepth to magnetic source
• Work by Clive Foss
(CSIRO)
• Individual magnetic
depth estimates based
on multiple inversions
of individual anomalies
• Gridded data to produce
both a map and surface
STRUCTURAL FRAMEWORK AND FLUID PATHWAYS
Based on known geology, potential field data and
seismic character a number of Domains and Seismic
Provinces have been identified
These domains are bound by a number of major shear
zones
• Jindarnga Shear Zone
• Palinar Shear Zone
• Border Shear Zone
• Mulyawara Shear Zone
• Mundrabilla Shear Zone
STRUCTURAL FRAMEWORK AND FLUID PATHWAYS
MAPPING BASEMENT UNDER COVER
Low magnetic Toolgana SS (~1600 Ma)
Non-magnetic intrusions – Undawidgi SS
(~1500Ma)
NNE and NE fabrics in Cook and Forrest
Domains and major structure reactivation
(1200 Ma?)
Intrusions of the ~1200 – 1140 Ma Moodini
SS
Intrusion of remnant magnetic bodies
intrusion of NNW trending dykes
Extension and deposition of Officer Basin
Intrusion of NW trending dykes?
MAPPING BASEMENT UNDER COVER
Coompana Drilling
Program designed to
ground-truth geophysical
interpretations and assist
in building a basement
geology map.
TECTONIC AND CRUSTAL EVOLUTION
Current available data provide
evidence for a number of events that
have affected the region
• Western Gawler events
• Inferred oceanic crust development in the
Coompana Province
• Magmatic-arc magmatism – Toolgana
Supersuite
• Within plate magmatism - Undawidgi Supersuite
(extension)
• A-type magmatism during the Maralinga Event –
Moodini Supersuite
TECTONIC AND CRUSTAL EVOLUTION
Toolgana Supersuite (~1620 – 1600 Ma)
Geochemical signature of subduction modified crust,
magmatic-arc related intrusions
Constrained by geochronology of magmatic rocks in the
Deakin Domain
Interpreted to be more widespread – inheritance,
geochemical signature in Hughes and Forrest domains
Correlated with similar units in the eastern Musgrave
Province and St Peter Suite
TECTONIC AND CRUSTAL EVOLUTIONToolgana Supersuite (~1620 – 1600 Ma)
• High K, calc-alkaline, magnesian
• LILE and LREE enriched, HFSE depleted
Chemistry typical of volcanic-arc setting
1540
1590
1640
1690
R20
125
49
R20
149
59
R19
613
88
R20
125
73
R19
614
32
R16
756
06
R16
756
07
R19
614
23
R19
613
34
R18
422
62
R10
391
40
R10
391
61
R10
391
53
R18
507
75
R21
348
56
R21
360
78
R21
360
69
R21
348
39
R21
360
59
R21
360
91
21
62
76
21
38
22
19
25
94
21
62
61
21
52
08
2
East Birksgate, St Peter Suite & Coompana Geochronology
TECTONIC AND CRUSTAL EVOLUTIONAn Evolving Arc System
St Peter arc complex - ~1650–1600 Ma
• Juvenile oceanic magmatic arc built on ~2000–1900 Ma
oceanic crust outboard of the Mawson/North Australian
Craton
Birksgate arc complex - ~1590–1540 Ma
Loongana arc - ~1415–1389 Ma
Wankanki arc complex - ~1350–1300 Ma
Progressively younging sequence of magmatic-arc
rocks as subduction retreats away from Gawler
Craton margin
TECTONIC AND CRUSTAL EVOLUTION
Undawidgi Supersuite (~1500 Ma)
• Apparently constrained to the Forrest Domain and one
occurrence in Mallabie 1
• Geochemical characteristics of rift related magmatism
• Associated with extensional structures in the Forrest
Domain
TECTONIC AND CRUSTAL EVOLUTIONMaralinga Event ~1220-1120 Ma
Seems to be major event recorded throughout the region
Associated with significant volumes of A type felsic and mafic magmatism
throughout the region – Including Shoshonitic Magmatism
Moodini Supersuite magmatism is syn- to late deformation
Associated with extensional fabric in the lower and mid crust which overprint
earlier fabrics, and crustal thinning
Magnetotelluric data seems to record the late effects of the Maralinga Event
and associated magmatism
IMPLICATIONS FOR MINERAL SYSTEMS• Geologically complex region
• A number of crustal scale structures identified, some coincident with MT conductors
• Recognition of a potential contiguous magmatic arc system out-board of the North
Australian/Gawler Craton begining at 1650–1600 Ma demonstrates a subduction
driven Mesoproterozoic evolution of southern Australia.
• Links between Provinces may allow us to map out these systems beneath cover –
potentially map where you are in the system in space and time
• western Gawler/GRV – backarc setting?
• Coompana
• Porphyrys/epithermal systems (crustal level?)
• Backarc orogenic/intrusion related
• Post-subduction magmatism - 1200 Ma
• Shoshonites – re-melting of subduction modified crust
A WORK IN PROGRESS
The work of the GSSA and our collaborators represents a significant
boost to the understanding of the geological history of western SA and
more broadly for Proterozoic Australia
By undertaking a consistent workflow from gap analysis to
comprehensive data and sample acquisition to synthesis, the GSSA
will provide arguably the greatest step-change in our geological
understanding of a region in modern times
And there’s still more to come………
DisclaimerThe information contained in this presentation has been compiled by the Department of the Premier
and Cabinet (DPC)and originates from a variety of sources. Although all reasonable care has been
taken in the preparation and compilation of the information, it has been provided in good faith for
general information only and does not purport to be professional advice. No warranty, express or
implied, is given as to the completeness, correctness, accuracy, reliability or currency of the
materials.
DPC and the Crown in the right of the State of South Australia does not accept responsibility for and
will not be held liable to any recipient of the information for any loss or damage however caused
(including negligence) which may be directly or indirectly suffered as a consequence of use of these
materials. DPC reserves the right to update, amend or supplement the information from time to
time at its discretion.