PLANKTIC FORAMINIFERAL BIOSTRATIGRAPHY AND 87Sr/86Sr ... · logical descriptions rare, except for a few Pliocene-Pleistocene stratigraphic sections of limited thickness (e.g., Zijderveld

J. Paleont., 69(1), 1995, pp. 7-20 Copyright ? 1995, The Paleontological Society 0022-3360/95/0069-0007$03.00

PLANKTIC FORAMINIFERAL BIOSTRATIGRAPHY AND 87Sr/86Sr ISOTOPIC STRATIGRAPHY OF THE

OLIGOCENE-TO-PLEISTOCENE SEDIMENTARY SEQUENCE IN THE SOUTHEASTERN CALABRIAN MICROPLATE,

SOUTHERN ITALY R. TIMOTHY PATTERSON,1 JOHN BLENKINSOP,' AND WILLIAM CAVAZZA2

'Department of Earth Sciences, Carleton University, Ottawa, Canada K1S 5B6 and 2Department of Mineralogical Sciences, University of Bologna, 40126 Bologna, Italy

ABSTRACT-Integration of foraminiferal biostratigraphy, 87Sr/86Sr isotope stratigraphy, and traditional physical stratigraphy has provided a refined age control of a poorly known Oligocene-to-Pleistocene sedimentary sequence nonconformably covering the crystalline basement complex of the Calabrian microplate, a continental block which rifted off the southern margin of the European plate during Neogene time. In spite of the fossil-poor content of the sequence, the simultaneous use ofpaleontological and geochemical techniques have resulted in the following conclusions. 1) The age of an unnamed, thin calcarenite unit locally present at the base of the sequence, previously considered Rupelian to early Aquitanian in age, has been refined to Chattian (27.8-24.8 Ma). This calcarenite was considered a basal, conformable member of the overlying Stilo-Capo d'Orlando Formation. However, this study indicates that it is separated from the Stilo-Capo d'Orlando Formation either by an angular unconformity or by a disconformity representing a significant time interval. 2) The Stilo-Capo d'Orlando Formation has a latest Chattian-earliest Aquitanian to Bur- digalian age. Previously published reports suggested deposition over a much longer time span, ranging from late Rupelian to Langhian. 3) An unnamed deep-marine siliciclastic unit mostly composed of conglomerate and sandstone and previously considered Tortonian in age is, in fact, Serravallian to Tortonian. 4) The depositional interval of the "trubi," fine-grained marine deposits, has been independently confirmed to span the Pliocene-Pleistocene.

The results of this study provide a framework for future sequence-stratigraphic and paleotectonic studies in the area, and prove the effectiveness of an integrated paleontological and geochemical (87Sr/86Sr) approach in the study of fossil-poor sedimentary sequences.

INTRODUCTION

THE NEOGENE geodynamic history of the western Mediter- ranean region is characterized by an intense phase of mi-

croplate dispersal (Dewey et al., 1973, 1989; Alvarez et al., 1974). The Calabrian microplate (CM) of southern Italy is one of the fragments of continental crust that rifted off the southern margin of the European plate and drifted southeastward to col- lide with the African plate (Dercourt et al., 1985; Malinverno and Ryan, 1986; Dewey et al., 1989). Along the southeastern, leading edge of the CM, an Oligocene-to-Quaternary sedimentary sequence mostly composed of marine deposits (Figure 1) records the major geologic events that affected the CM during the rifting and drifting phases and after its collision with the African margin (Cavazza, 1992). A good stratigraphic under- standing of this sedimentary sequence is essential in order to constrain the timing of the geodynamic evolution of the CM. In spite of its excellent outcrops, the stratigraphic framework of the sequence is poorly known, and detailed micropaleontological descriptions rare, except for a few Pliocene-Pleistocene stratigraphic sections of limited thickness (e.g., Zijderveld et al., 1986, 1991; Hilgen, 1987). The purpose of this paper is to provide a firmer biostratigraphic and 87Sr/86Sr isotope-stratigraphic framework, to serve as a basis for future sequence- stratigraphic analysis, geohistory analysis, and, ultimately, for the study of the timing of CM geodynamic events.

STRATIGRAPHIC FRAMEWORK

The basement underlying the studied sedimentary sequence is composed of Hercynian granitoid plutons intruding mostly metasedimentary rocks. This basement complex is locally cov- ered nonconformably by erosional remnants of Mesozoic carbonates (Roda, 1965).

Thin and discontinuous veneers of unnamed Tertiary calcarenite with a variable siliciclastic component unconformably

overlie the Mesozoic carbonates or rest directly on the crystalline basement (see, for example, the base of the Stilo section in Figure 2). The calcarenite is present only in the northern part of the study area (approximately from Stilo to Stignano, Figure 1). It contains a wealth of shallow-marine fossils, including macro- foraminifera (Lepidocyclina, Operculina, Heterostegina, Am- phistegina, Asterigerina; Bonardi et al., 1971), bryozoans, mol- lusks, and calcareous algae. Virtually all the large fossils are broken and even smaller foraminiferal tests are commonly broken or abraded. The occurrence of grain-size grading further indicates that the calcarenite unit was the product of gravity flows resedimenting shelf deposits in a deeper marine environment. According to Afchain (1966), the age of the calcarenite unit is early Oligocene to early Aquitanian. Bonardi et al. (1971, p. 150-151) indicated a generic late Oligocene to Aquitanian age for two calcarenite sequences of 10 and 15 m cropping out near the town of Stilo. Such a long stratigraphic range for a unit no more than 20 m thick clearly indicates poor biostratigraphic control.

Stratigraphically higher in the section is the Stilo-Capo d'Or- lando Formation (SCO Fm, Bonardi et al., 1980), a marine unit composed of a series of coarse-grained submarine-canyon fills, laterally equivalent muddy slope-deposits, and base-of-slope sandstone aprons (Cavazza, 1989; Cavazza and DeCelles, 1993). Weltje (1992) identified shallow marine facies at the top of the SCO in the Aspromonte region of southernmost Calabria. The SCO Fm overlies unconformably either the basement or, locally, the calcarenite described earlier (Figures 1, 2). The age of this unit has not been clearly determined. According to Bonardi et al. (1971, 1980), who formally established the unit, the SCO Fm has a late Aquitanian-Langhian age, based on nannoplankton and planktic foraminifera. This interpretation is not consistent with the results of the planktic-foraminiferal and nannoplankton studies of Meulenkamp et al. (1986), Barrier and

7

This content downloaded from 134.117.10.200 on Tue, 09 Jun 2015 01:32:19 UTCAll use subject to JSTOR Terms and Conditions

http://www.jstor.org/page/info/about/policies/terms.jsp

JOURNAL OF PALEONTOLOGY, V. 69, NO. 1, 1995

FIGURE I-Schematic geologic map of southern Calabria showing locations of measured stratigraphic sections examined for this study (after Cavazza and Dahl, 1990).

Montenat (1987), and Courme and Mascle (1988). Their research indicates that the unit is Chattian-Burdigalian age. Min- zoni et al. (1992) indicate a generic early Oligocene-early Mio- cene age, based on macrofossils, planktic foraminifera, and calcareous nannofossils. Weltje (1992), using dinoflagellate biostratigraphy and unpublished nannoplankton data, indicated a late Rupelian-early Burdigalian age. Unfortunately, none of these conflicting studies report exact sample locations. During this study, the SCO Fm was sampled along seven measured stratigraphic sections. Simplified depictions of the Stilo, San Paolo, Monte Tronato, Bova, and Amendolea stratigraphic sections are shown in Figure 2. Two additional sections were measured and sampled in Sicily (at Francavilla and Capo d'Orlando); unfortunately, all samples taken from the Sicilian sections were barren or contained very few specimens.

The SCO Fm is overlain by a poorly known melange unit informally named "argille varicolori" (varicolored clays) by Amodio-Morelli et al. (1976). This unit is composed of a Cre- taceous-Paleogene mudrock matrix enclosing Oligocene-Mio- cene quartzarenite knockers. The unit has been interpreted al- ternatively as a tectonic melange (Amodio-Morelli et al., 1976) or as a large-scale olistostrome (Gorler, 1978). More than forty samples taken from the "argille varicolori" along the Stilo section and near Plati (12 km southwest of Monte Tronato, Figure 1) were barren or contained only a few recrystallized specimens. A stratigraphic and structural study of the "argille varicolori" is under way in order to constrain the mechanism and timing of emplacement of this unit.

Erosively overlying the "argille varicolori" is an unnamed deep-marine unit composed of sandstone, mudrock, and conglomerate (see the Stilo and Stignano A stratigraphic sections in Figure 2), and generically considered middle-late Miocene in age in the geologic map of Calabria (Cassa per il Mezzogiorno, 1968-1972). According to Bonardi et al. (1971), this unit has a Tortonian age, on the basis of planktic foraminifera biostratigraphy. Detailed litho- and biostratigraphic analyses of this unit are lacking.

The unnamed "Tortonian" unit is erosively overlain by coarse- grained Messinian (Vai, personal commun., 1990) fanglomerates deposited during the late Miocene relative sea-level fall that

occurred in the Mediterranean Sea. Deposition of this unit was induced by a combination of tectonism and lowered base level causing subaerial valley overincision, increased sediment sup- ply, and fan-delta progradation at the basin margins. Messinian conglomerates are present in the Stilo and Stignano B stratigraphic sections (Figure 2). Messinian evaporites, which commonly underlie the fanglomerates in other areas, are absent in the studied stratigraphic sections.

Overlapping the Messinian conglomerates is a complex Plio- cene-Quaternary sedimentary sequence that includes the Trubi Formation, a fine-grained marine unit deposited after the re- establishment of relatively normal marine conditions in the Mediterranean Sea following the Messinian salinity crisis. The "trubi" are mostly composed of distinctive couplets made of alternating limestone and marl that have been interpreted as being deposited in response to orbitally induced variations of paleoceanographic regime (Hilgen, 1987; Thunell et al., 1992). The "trubi" have been studied in great detail-both biostrati- graphically and magnetostratigraphically-in Calabria and Sic- ily because the base of the unit is considered by definition the Miocene-Pliocene boundary (Cita, 1975; Zijderveld et al., 1986; Channell et al., 1988), and because they contain the Pliocene- Pleistocene boundary in their upper portion (Rio et al., 1991; Zijderveld et al., 1991). Furthermore, in spite of several problems related to marked faunal provincialism and to recurrent local differences in paleoceanographic conditions, the Mediter- ranean Neogene stages are still commonly used as the standard stages in most geologic time scales. The "trubi" are present in the Stilo, Stignano A, and Stignano B stratigraphic sections (Fig- ure 2).

The whole sedimentary sequence just described as well as the basement complex are unconformably overlain by upper Qua- ternary sediments. This interval was deposited under fluvial and transitional conditions, and can be found at elevations in excess of 1,000 m, documenting the dramatic tectonic uplift of the CM during late Quaternary time (e.g., Barrier and Montenat, 1987).

APPLICATION OF 87SR/86SR RATIOS TO ESTIMATING AGES OF SEDIMENTARY ROCKS

Chemical weathering of rocks on the continents releases strontium into solution in lakes, rivers, and groundwater. The Sr released into solution is isotopically homogenized by mixing during transport to the oceans, where it re-enters the rock cycle primarily by coprecipitation with calcium carbonate in living organisms (Faure, 1986). The isotopic composition of strontium in present-day seawater is identical everywhere, due to the high solubility of this element. In fact, required time for 87Sr/86Sr ratio homogenization through all the world's ocean is only 1,000 years (Faure, 1982).

The 87Sr/86Sr ratio of sea water is controlled by the mixing of isotopic variants of Sr derived from three main sources: 1) young volcanic rocks, 2) old sialic rocks of the continental crust, and 3) marine carbonate rocks of Phanerozoic age. Therefore, the strontium isotopic ratio of sea water has changed through geologic time in response to the kind of rocks exposed to chemical weathering on the Earth's crust and to tectonism (e.g., Raymo et al., 1988; Edmond, 1992). Systematic temporal variations in the 87Sr/86Sr ratio of unaltered calcium carbonate of fossil shells have been extensively investigated and have led to the development of a curve depicting the variations of the ratio of sea water through Phanerozoic time (e.g., DePaolo and Ingram, 1985; DePaolo, 1986; Hesse et al., 1986; Koepnick et al., 1988; Veizer, 1989). The curve can be used for the numerical dating of carbonate fossil material of marine origin (e.g., Hurst, 1986; McKenzie, 1986; Rundberg and Smalley, 1989).

8



PATTERSON ET AL. -OLIGOCENE-PLEISTOCENE SEQUENCE IN ITALY

<CA30 (1360) CA29 (1345)

~Cr_ <CA28 (1325) EC:: <CA27 (1315)

CD ...... <CA26 (1300)

c-)

CO, <CA25 (1165) O <CA24 (1136)

Mes. 444 .

300-

200-

<CA23 (1086)

>0 >0

>0

>00 >p0 >0 >0 >0 >0

100- <CA22 (999)

0 m-

<CA21 (843)

03

uat.

a)

CZ

Co .::

.E 0) (n Q)

V.C.

<cA20 (808) Stignar <CA19 (776) <CA18 (760) 800

: <CA15.16,17 (735) C '

.:i:: <CA14 (723) :i <CA13 710 8 <CA12 693

CCA11~~~~~~~( 615 <CA11 (615) <CA10 (614

<CA7 (560) <CA6 (525)

<CA5 (470) -cCA4 {45n\ E

" 00000 O 00000

00000 0 o oo O 00000

00000

00 00 0

O 00 00 " 0000C 0 ooooo

oL 00000

o 00000

00000 r 00000

C ) o oo o o 00000 00000 ooooo<

00000

oo o 444

00000

Stilo Sect.

600-

c c1

.-

ct e1

L.

(a cn

200-

400-

;A3 (304)

CA2 (155)

;A1 (52meters)

<CA110 (325)

300- <CA109 (280)

_---- <CA108 (245) -= <CA107 (220)

- <CA106 (210)

.... <CA105 (180)

*0000' 0000, 0000, 0000,

oo0000 100- '0000'

'0000' '0000' '0000' '0000' '0000'

On

io B Sect.

(3 cr

0 o E

o 0

: cr ,-, 0

CZ cr1

I O

Bno

Bov

<CA104 (715)200- t.. !i: i':. i <CA103 (705) ::i::: <CA102 (692)

: <CA101 (650) .000 0?<CA100 (615)

0000C

0000C OOOOC oo0.0 100-

0000(

0000~

OOOO? 0000:

0000 0000? 0000(

Om- 0000(

??ooC M.Tr 0000: 0 o 0 0 '<CA99 (210) 0000?

^o .<CA98 (195) <CA97 (175)

- <CA96(125) -B <CA95 (90)

O m-

V.C.

IL

co

0 L-

0

C

> CA63,64,65, <CA72 (328) 66 (510,515 <CA71 (320) 500 530, 538) 500' ~ 4 4 O 4 <CA70 (280) 0 > 0

;,.0000

E :30000 400- ' 0oooo

LL o o o o <CA69 (195) 0 O CA O >

o o o? |<CA62(350) <CA68 (180)2 (350) <CA67(165) C00 > 300- .L- .

00000 O o000oo 00000 30 o000

00000 ,0000 4 4 o 4o o 44 :, o0 <CA61(225) 00000ooo 200 ~-coooo 00000o ooo 00000 O 0000 o00000 I, I... <CA60 (152) ooooo gO

:i:!:!:!:!:! <iiiiiii! <CA59 (128)

.', s , , 100- () 0000 .'/'.'/'-- : , 0000

......... <CA58 (52) a Sect. 0 4?o <CA57(25) o o 0 4 4 0 m _, ,,/, //,/,. i I/ / / "

,<cA56(200)Amendolea Sect. <CA55 (199)

E LL <CA48 (140) o <CA47 (135)

b I

a, (d 3 <CA54 (50) O <CA53 (37)

, _^B<CA52 (30) _ <CA51 (20)

O^ _*<CA50 (12) ) ^ CA49 (4)

onato Sect.

<CA46 (62) <CA45 (51) <CA44 (44) <CA43 (38) <CA42 (35) <CA41 (31) <CA40 (27)

San Paolo Sect. _- unconformity

confol "trubi"

E3<%<, ,.: d;l

ii. . . . . i1 iii : ..;i cI.. .. . .. .

I;,..... Stignano A Sect.

rmable contact

"varicolored clays" (melange)

mudrock

sandstone

conglomerate

calcarenite basement (includes a local thin cover of Mesozoic carbonates)

FIGURE 2-Schematic diagrams of stratigraphic sections examined for this study, showing position of collected samples. Numbers in parenthesis indicate position of samples above base of section, in meters.

1

-[

Mes. o o <

000C

000

o 000 0 oo H 000

0 000

000 Cr1

a)o (/) :::::::::::::::::::::

1400

1200

1000

800

600

400

200

0 m

c t-0 O o3

9

Ro

-%- k--,.,v/



JOURNAL OF PALEONTOLOGY. V. 69. NO. 1. 1995

TABLE 1- Latitude and longitude of sampled intervals bearing foraminifera and/or where a 87Sr/86Sr date was obtained.

Latitude 38028'50"N 38028'44"N 38028'35"N 38028'39"N 38028'22"N 38028'22"N 38?28'11"N 38028'14"N 38?28'12"N 38028'02"N 38027'08"N 38027'12"N 38026'57"N 38026'58"N 38027'00"N 38016'19"N 38016'13"N 38016'12"N 38?15'28"N 38?15'29"N 38015'30"N 38015'18"N 38015'18"N 37058'50"N 37056'21"N 37?56'28"N 38026'13"N 38?26'1 1"N 38026'08"N 38024'34"N 38024'23"N 38024'08"N 38023'57"N 38023'26"N 38023'16"N 38022'25"N 38022'40"N 38028'49"N 38025'40"N 38?25'46"N 38028'04"N

Longitude' 4?01'28"E 4?01'33"E 4001'37"E 4?02'00"E 4?02'01 "E 4002'10"E 4002'15"E 4002'37"E 4003'07"E 4003'07"E 4004'36"E 4005'02"E 4?05'19"E 4?05'39"E 4?05'40"E 3?43'30"E 3?43'40"E 3043'42"E 3?43'31"E 3?43'30"E 3?43'29"E 3043'39"E 3?43'39"E 3?25'55"E 3029'25"E 3029'25"E 4001'03"E 4001'03"E 4001'04"E 4003'02"E 4?02'39"E 4?00'24"E 400'31"E 4?00'43"E 4?01'15"E 4?01'18"E 4?01'29"E 4000'48"E 3058'48"E 3058'52"E 4?00'09"E

Section Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo Stilo San Paolo San Paolo San Paolo Monte Tronato Monte Tronato Monte Tronato Monte Tronato Monte Tronato Amendolea Bova Bova Stignano A Stignano A Stignano A Stignano A Stignano A Stignano B Stignano B Stignano B Stignano B Stignano B Stignano B Stilo

Strati- graphic position

450 m 525 m 615m 760 m 776 m 843 m 999 m

1,086 m 1,136 m 1,165 m 1,300 m 1,315 m 1,325 m 1,345 m 1,360 m

27 m 135 m 140 m 12m 20 m 30 m

199 m 200 m 152 m 280 m 328 m 90 m

125 m 175 m 705 m 715m 180 m 210m 220 m 245 m 280 m 325 m

-10m

' Longitudes refer to the Monte Mario meridian (Rome). 2 These samples have been taken from small scattered outcrops of the

basal calcarenites.

METHODS AND MATERIALS

Samples for micropaleontological and 87Sr/86Sr analyses were collected in May 1990 by W. Cavazza and R. T. Patterson along seven measured stratigraphic sections in southern Calabria, It- aly. Only mudrocks were sampled (Table 1) and the sampling interval varied considerably depending on local lithology. Bulk samples were dried and then soaked in kerosene. The kerosene was decanted and water added to each sample. The largely dis- aggregated samples were further broken down in a solution of boiling soda ash, and washed in a sieve of 200 Taylor equivalent mesh size (75-,um openings). The residue was dried and the foraminifera removed by heavy-liquid separation (CCl4, s.g. 1.56). The planktic foraminiferal makeup of each sample was then qualitatively determined. The sample processing procedure described above does not affect the 87Sr/86Sr ratio contained within the foraminiferal tests (R. Capo, personal commun., 1988).

An aliquot of 1.0 to > 10 mg of foraminiferal tests or mollusk shell material was handpicked from selected samples (Table 2). Samples were cleaned in distilled water to remove sediment, crushed, and then dissolved in 2.5 M hydrochloric acid. The fraction (Sr + Ca) was separated using an ion-exchange column of Bio-Rad AG50 X-8 resin, with 2.5 M Hcl as the eluting agent.

TABLE 2-87Sr/86Sr values and derived ages (Miller et al., 1988) of foraminifera and bivalve shells (CA-56 only) from various localities in Calabria. Average 87Sr/86Sr are given in parts per million with an experimental error of +0.00002. Values plotted on the seawater Sr reference curve have been adjusted to a value of 0.71025 for the NBS 987 Sr standard. * All "trubi" sample 87Sr/86Sr ratios provided anomalously young age estimates inconsistent with the foraminiferal biostratigraphy. See discussion for possible explanation.

Sample 87Sr/86Sr Age estimate

CA-11 0.70854 19.6 (19.3-19.9) CA-18 0.70886 13.3(11.8-14.9) CA-19 0.70887 12.5(11.0-14.1)

*CA-23 0.70905 2.2 (1.8-2.5) *CA-25 0.70912 1.0 (0.7-1.3) *CA-26 0.70924 <0.0 *CA-28 0.70918 0.0 (0.3-0.0) *CA-30 0.70920 <0.0 CA-40 0.70851 20.1 (19.8-20.5) CA-51 0.70837 22.5 (22.1-22.8) CA-56 0.70870 16.9 (16.6-17.3) CA-95 0.70887 12.5 (11.0-14.1) CA-96 0.70887 12.5(11.0-14.1) CA-97 0.70891 9.4 (7.8-11.0)

*CA- 104 0.70916 0.3 (0.0-0.7) *CA-107 0.70914 0.3 (0.3-1.0) *CA-110 0.70914 0.7 (0.3-1.0) CA-116 0.70799 31.8(31.2-32.4) CA-120 0.70813 27.8 (27.2-28.4) SCO-88-6 0.70805 30.1(29.5-30.7) SCO-88-10 0.70823 24.8 (24.5-25.2)

The separation of Sr from Ca was carried out on a second column consisting of Teflon powder coated with bis (2-ethylhexyl) phos- phoric acid (HDEHP), with 0.01 M HC1 as the eluting agent (Blenkinsop, unpubl. method). The isotopic composition of the Sr was measured on a Finnigan-MAT 261 multicollector mass spectrometer, operated in the static mode. Replicate analyses of the NBS 987 Sr standard yield a 87Sr/86Sr ratio of 0.71025 ? 0.00002, and a ratio of 0.70802 + 0.00002 for the Eimer and Amend standard. The precision reported in Table 2 is estimated from replicate analyses of the standards, and is twice the standard deviation of a measurement. Internal precision (standard deviation of the mean) for all analyses was less than 0.00001. We use this value only as a monitor of the quality of the analysis, and do not report it. Similarly, as the uncertainty in the 87Sr/ 86Sr ratio is 2 in the fifth decimal place, we quote our results to five significant figures. Ages given in Table 2 and Figures 3-7 were calculated from regressions given by Hodell et al. (1991) and Miller et al. (1988, 1991). Insufficient fossil calcium carbonate was available in the Bova (Figure 8) and Amendolea (Figure 9) stratigraphic sections to obtain 87Sr/86Sr ratios.

All planktic foraminiferal taxa utilized in the biostratigraphic analyses were illustrated (Figures 10-12) using the JEOL 6400 Scanning Electron Microscope in the Department of Earth Sci- ences, Carleton University.

DISCUSSION

The biostratigraphic and isotope stratigraphic data generated by this study, integrated with stratigraphic and sedimentologic field data, have resulted in several refinements of the stratigraphy of the studied sedimentary sequence. The basal calcarenite, previously considered generically as late Oligocene to Aquitanian in age (Afchain, 1966; Bonardi et al., 1971), can now be ascribed exclusively an Oligocene age (Table 2). This attribution is based on four strontium isotope dates of calcareous shells (samples CA-116, CA-120, SCO-88-6, and SCO-88-10), ranging in age from 31.8 to 24.8 Ma. The calcarenite is at most 20 m thick and does not show any evidence of condensed sed-

Sample CA004 CA006 CA011 CA018 CA019 CA021 CA022 CA023 CA024 CA025 CA026 CA027 CA028 CA029 CA030 CA040 CA047 CA048 CA050 CA051 CA052 CA055 CA056 CA060 CA070 CA072 CA095 CA096 CA097 CA103 CA104 CA105 CA106 CA107 CA108 CA109 CA110 CA116 CA1202 SCO-88-62 SCO-88-102

10



PATTERSON ET AL. - OLIGOCENE-PLEISTOCENE SEQUENCE IN ITAL Y

Planktic Foraminifera

Stilo

. Section>

Pleist. Cal. N22

L.Plio. Piac. N21

E. Plio. Zanc. N19-20

L. Mio. Tort. N16-17 (1) 0

(1) 0 0 .2

(1) 0

'0

-Iw

c

co

u) Cl)

aI

*"

c

oi -; 3

%ll

N12-13

N4-6

8786Sr Sri Sr Samples a. o

CA030 CA029 CA028 CA027 CA026 CA025 CA024 CA023 CA022 CA021 CAO20 glllll

12.4 Ma -_ CA019 13.3 Ma - CAO18

CAO157 |::|

C- - - - - - - - - -_CO - 4- -

- :.ii :

CA016 siiii CA015 i:::=:

19.6 Ma_ -CAO11

CA009 'ii::.:::i:::: ii CA008

-1- 6Ma -- CAO11 ifii

CA004 ---------- CA004I CA003 ii. CA002 .:

----------CAQQi

FIGURE 3--Stratigraphic distribution of Miocene to Pleistocene foraminifera from the Stilo section showing sampled intervals and age of units, based on planktic foraminiferal ranges and the 87Sr/86Sr curve. Dotted pattern indicates lack of fossils. Figure not to scale. For exact stratigraphic location of samples, see Figure 2.

imentation; it is therefore unlikely that it would encompass such a long time span, as previously suggested. Field and microscopic observations indicate that this unit is composed of shallow- marine material (including fossils) of various ages reworked and redeposited by gravity flows into a deeper marine environment. Considering the resedimented nature of the calcarenite, the younger isotopic ages (27.8-24.8 Ma, Chattian) should provide the best age control for this unit, whereas older ages probably derive from resedimentation of older material. Afchain (1966) and Bonardi et al. (1971, 1980) considered the calcarenite to be the basal member of the overlying Stilo-Capo d'Orlando For- mation but, in fact, they are separated by a significant unconformity. The unconformity can be represented by a disconformity or by a low-angle (10-15 ) unconformity, like the one visible along the northern bank of Fiumara Stilaro just north of Stilo.

Other characteristics differentiating the calcarenite from the SCO Fm are: 1) the presence of rare subangular calcarenite clasts at the base of the SCO Fm, indicating that the calcarenite was already lithified when deposition of the SCO Fm occurred, and 2) the discontinuity of the calcarenite outcrops (as opposed to the continuous outcrops of the overlying SCO Fm), indicating that some erosion of the calcarenite unit must have occurred before deposition of the SCO Fm.

As mentioned earlier, several authors have considered the SCO Fm a continuous Oligocene-to-lower Miocene stratigraphic unit. For example, Weltje (1992, p. 42) indicated a late Ru- pelian to early Burdigalian age, covering a time span of more than 12 Ma. Considering that the maximum thickness of the SCO in Calabria is 625 m (Cavazza and DeCelles, 1993), this would result in a very low sedimentation rate of less than 52m/

~3-A~ ~>7;F .'f. '1P.S..'.T '-rz.r??rlrr rrmm mrrr ??.l:,:IT:'(Cl?55t.;??lti????T ?;CT?"?.i:.:,;??I L" '" ?C? ? "' CC' " T C5 '-??'?T;??trT?f.r.t?ll;f?5c I Y ?LL .W CY??Y?:?I?;?iiiS?;t:l.?.?.?..?.?. .?.?;;!;I;?;rliiiiiiiiiIiijiii:i:iiI..... ?:?.::: ::iiij:r:i '''''''''' ?;?:?;;?iiiiiiIiiiii iiiiiriiiiiiiiiIi iriI :?? i: ???????..ijij iii'.'.' I ..? ?I-.- ;?;';?;a';?.?-' *i?;o;?.cu u.u

11





KStignano' ,Section A,

87i Sr

E. Pliocene? Zanclean? N18-20?

L. Miocene? Tortonian? N15-17?

L. Miocene Tortonian N15

M. Miocene Serravallian N12-13

-I I . E ?

O ? ? ', 0 E

L .z X X |

rI Sr ? Samples E '

CA103 i C1 ...... . : .. . ...................................................................-.........-.

________ _ _ _ _ _.-.-......... -.. .. ...... -.. - ---....... . ..... . .. ..... .. . . ..

CA100

9.4 Ma--~CA097 1 1 1 12.5 Ma-- CA096 - - -

FIGURE 4-Stratigraphic distribution of Miocene to Pliocene foraminifera from the Stignano Section A, showing sampled intervals and age of units, based on planktic foraminiferal ranges and the 87Sr/86Sr curve. Dotted pattern indicates lack of fossils. Figure not to scale. For exact stratigraphic location of samples, see Figure 2.

Ma, much less than those documented for analogous turbidite systems in tectonically active settings (Stow et al., 1985). In spite of the poor paleontologic content of the SCO Fm (only 12 out of 67 samples collected in Calabria and none out of 23 samples collected in Sicily yielded a significant number of specimens), integrated biostratigraphic and geochemical results of this study indicate a latest Chattian-earliest Aquitanian to Bur- digalian age (Figures 3, 6-9; Table 2), in agreement with the presence of an unconformity with the older underlying Chattian calcarenite. Four strontium age estimates of the SCO Fm range between 22.5 and 16.9 Ma. It is most likely that older Oligocene ages reported by some authors for the base of the SCO (e.g., Courme and Mascle, 1988; Minzoni et al., 1992; Weltje 1992)


4)

0

>)

L co

FIGURE 5--Stratigraphic distribution of Pliocene foraminifera from the Stignano Section B, showing sampled intervals and age of units, based on planktic foraminiferal ranges and the 87Sr/86Sr curve. Figure not to scale. For exact stratigraphic location of samples, see Figure 2.

are the result of incorporation of the thin basal calcarenites (or of some lateral equivalent) into the SCO Fm. The database of this study is insufficient to define beyond doubt the exact age of this unit, but provides additional constraints that may serve as a base for future study.


*.

ct

"San Paolo 1 E ~ .

Section J > 87 86 X Sr/ Sr, , P

Samples u 2 c CA048

| CA~0 46 : :.;.. ....................

CA045 ! N4B CA044

E--:

a0.1 Ma-"^CA040 |I l I

CA042 ""~ "'~"~ 1

FIGURE 6- Stratigraphic distribution of early Miocene foraminifera from the San Paolo Section, showing sampled intervals and age of units, based on planktic foraminiferal ranges and the 87Sr/86Sr curve. Dotted pattern indicates lack of fossils. Figure not to scale. For exact stratigraphic location of samples, see Figure 2.

- -

12



PATTERSON ET AL. - OLIGOCENE-PLEISTOCENE SEQUENCE IN ITALY


Monte Tronato> Section

87 r86sr Sr/ Sr Samples

-d N7 16.9 Ma MCA056 C '- N7 . :e CA055

8 =

.. ......AQ54. S 5) ...... - . CA053..

C N4B-6 - - CA052 .5 ?22.5 Ma- CA051 w ..........

cr -- CA050 .. ... C......CA0 49.

t7"Latest Cattian? SLate Oligocene?

o .. ...:.

^ o n-

-o - - oo

ii~!: cS.-!.-. '::-:.::::...........

... .... :....--

: ::::::::::

FIGURE 7- Stratigraphic distribution of early Miocene foraminifera from the Monte Tronato Section, showing sampled intervals and age of units, based on planktic foraminiferal ranges and the 87Sr/86Sr curve. Dotted pattern indicates lack of fossils. Figure not to scale. For exact stratigraphic location of samples, see Figure 2.

In spite of the different opinions on the mechanism, there exists general agreement that the emplacement of the "varicolored clays" took place in Langhian time (middle Miocene) (Amodio-Morelli et al., 1976; Bonardi et al., 1980; Courme and Mascle, 1988). The unnamed deep-marine sedimentary unit erosively overlying the "varicolored clays" has been tradition- ally considered as Tortonian (e.g., Bonardi et al., 1971), thus implying a significant stratigraphic hiatus between the two units, covering at least the whole Serravallian (>5 m.y.). Biostrati- graphic results of this study and five strontium-isotope age estimates ranging between 13.3 and 9.4 Ma indicate that the overlying unit has a middle Serravallian-Tortonian age (Table 2, Figures 3, 4) and therefore that the erosional surface at the base of this unit covers a shorter time interval. Furthermore, all samples from the lowermost, 60-m-thick sandy member of this unit in the Stilo section were barren (Figure 3), and therefore the basal member of the Serravallian-Tortonian unit may be significantly older than 13.3 Ma.

All of the 87Sr/86Sr ratios measured in samples obtained from the "trubi" (CA-23, CA-25, CA-26, CA-28, CA-30, CA-104, CA-107, and CA-1 10) provided anomalously young age estimates (higher 87Sr/86Sr ratios) inconsistent with the paleontological results (Table 2). Recent reports by other researchers may explain these anomalous results. The "trubi" consists of alternating marl and limestone couplets. Thunell et al. (1992) interpreted these couplets to indicate periods of higher (limestone deposition) and lower (marl deposition) biological productivity. Their model invokes intensified winds associated with precession maxima resulting in increased upwelling and higher productivity associated with limestone deposition. Alternative- ly, Gudjonsson and Van der Zwaan (1985) and DeVisser et al. (1989) have proposed that the rhythmic bedding of the "trubi"

Bova '

SectionJ

Sample CA072 CA071 CA070 CA069 CA068 CA067


XO O

is o s . .

'S b

............. .. *...................

FIGURE 8-Stratigraphic distribution of Miocene foraminifera from the Bova Section, showing sampled intervals and age of units, based on planktic foraminiferal ranges and the 87Sr/86Sr curve. Dotted pattern indicates lack of fossils. Figure not to scale. For exact stratigraphic location of samples, see Figure 2.

is related to periodic changes in precipitation and runoff caused by precession-controlled changes in monsoon intensity.

Levels of radiogenic strontium (87Sr/86Sr) directly measured from terrestrial sources and restricted basins subject to fresh- water runoff are usually much higher than those measured from marine sources (Raymo and Ruddiman, 1992; Andersson et al., 1993). The elevated levels of 87Sr/86Sr in some of the measured samples therefore may reflect an input of continental Sr and/or some modifications of the paleoceanographic regime. Diagenetic


(Amendolea : '

Section J SI

Samples ; a

CA066 CA065 CA064 CA063 CA062 CA061) CA060 CA059 CA058 CA057

E. Mio.?IAqui.?IN4B? iI ri :.Xiii.l::::?i

FIGURE 9-Stratigraphic distribution of Miocene foraminifera from the Amendolea Section, showing sampled intervals and age of units, based on planktic foraminiferal ranges and the 87Sr/86Sr curve. Dotted pattern indicates lack of fossils. Figure not to scale. For exact stratigraphic location of samples, see Figure 2.

13

F

I .1

1 5

I . I .:

I .1.




alteration of strontium in fossil material is not a factor here; in fact, detailed examination of the "trubi" by reflected light and scanning electron microscopy reveals no evidence of recrystal- lization. A detailed analysis of a large number of samples from both marls and limestones is presently underway by the authors to determine whether a consistent pattern of 87Sr/86Sr ratios is present in the marls and limestones. Recognition of such a pattern would suggest that, at least in smaller basins, 87/86Sr ratios might provide useful indicators of climatic change.

Despite the problems with the 87Sr/86Sr ratios, biostratigraphic analysis of the rich foraminiferal fauna of the "trubi" provides confirmation that the Pliocene-Pleistocene boundary is contained within this unit (Hilgen, 1987; Zijderveld et al., 1991). For example, in the Stilo section the boundary is present within a shallow-marine mudrock body between samples CA-27 and CA-28 (Figures 2 and 3), as indicated by the first appearance of Truncorotalia truncatulinoides (d'Orbigny, 1839a).

In conclusion, this research has proved the effectiveness of an integrated paleontological and geochemical approach in the

study of fossil-poor sedimentary sequences, where traditional biostratigraphic methods may not provide enough chronologic resolution. The combined use of 87Sr/86Sr isotope stratigraphy, foraminiferal biostratigraphy, and stratigraphic and sedimentologic data has allowed the development of a refined stratigraphic framework that will be used for future sequence-stratigraphic and paleotectonic research.

ACKNOWLEDGMENTS

This research was partially supported by Natural Sciences and Engineering Research Council of Canada (NSERC) Operating Grant OGP0041665 to R.T.P., a grant from Ministero dell'Universita e della Ricerca Scientifica e Tecnologica (MURST) to W.C., and a NATO Collaborative Research Grant to R.T.P. and W.C. We thank R. Barbieri, A. Negri, G. B. Vai, and referees A. J. Arnold, J. P. Beckmann, D. A. Hodell, K. G. Miller, and D. C. Steinker for critically reviewing the manu- script. M. Dall'Olmo and S. Gangemi provided field assistance.

FIGURE 10-1, Paragloborotalia nana (Bolli, 1957), umbilical view of specimen from sample CA-6 of the Stilo section, Stilo-Capo d'Orlando Formation, early Miocene, x 300. 2, Neogloboquadrina pachyderma (Ehrenberg, 1861), umbilical view of specimen from sample CA-26 of the Stilo section, unnamed formation, Pleistocene, x 300. 3, Neogloboquadrina dutertrei (d'Orbigny, 1839b), umbilical view of specimen from sample CA-26, of the Stilo section, unnamed formation, Pleistocene, x 370. 4, Neogloboquadrina acostaensis (Blow, 1959), umbilical view of specimen from sample CA-24 of the Stilo section, unnamed formation, early Pliocene, x 200. 5, Globigerina woodi Jenkins, 1960, umbilical view of specimen from sample CA-50, of the Monte Tronato section, Stilo-Capo d'Orlando Formation, early Miocene, x 200. 6, Globigerina bulloides d'Orbigny, 1826, umbilical view of specimen from sample CA-23 of the Stilo section, unnamed formation, early Pliocene, x 130. 7, Tinophodella glutinata (Egger, 1893), umbilical view of specimen from sample CA-26, of the Stilo section, unnamed formation, Pleistocene, x 350. 8, Globigerina quinqueloba Natland, 1938, umbilical view of specimen from sample CA-26 of the Stilo section, unnamed formation, Pleistocene, x 270. 9, Globigerina ciperoensis Bolli, 1954, umbilical view of specimen from sample CA-70, of the Bova section, Stilo-Capo d'Orlando Formation, early Miocene, x 250. 10, Globoquadrina dehiscens (Chapman, Parr, and Collins, 1934), umbilical view of specimen from sample CA-95, of the Stignano Section, unnamed formation, middle Miocene, x 220. 11, Dentoglobigerina altispira altispira (Cushman and Jarvis, 1936), umbilical view of specimen from sample CA-95, of the Stignano Section, unnamed formation, middle Miocene, x 170. 12, Sphaeroidinellopsis seminulina seminulina (Schwager, 1866), umbilical view of specimen from sample CA-105, of the Stignano Section, unnamed formation, early Pliocene, x 190.

FIGURE 11-1, Globigerinoides trilobus (Reuss, 1850), umbilical view of specimen from sample CA-26 of the Stilo section, unnamed formation, Pleistocene, x 400. 2, Globigerinoides quadrilobatus (d'Orbigny, 1846), umbilical view of specimen from sample CA-18 of the Stilo section, unnamed formation, middle Miocene, x 200. 3, Globigerinoides bulloideus Crescenti, 1966, umbilical view of specimen from sample CA-95, of the Stignano Section, unnamed formation, middle Miocene, x 250. 4, Globigerinoides sacculifer (Brady, 1877), umbilical view of specimen from sample CA-26 of the Stilo section, unnamed formation, Pleistocene, x 130. 5, Globigerinoides extremus Bolli and Bermudez, 1965, umbilical view of specimen from sample CA-23 of the Stilo section, unnamed formation, early Pliocene, x 170. 6, Globigerinoides obliquus Bolli, 1957, umbilical view of specimen from sample CA-24 of the Stilo section, unnamed formation, early Pliocene, x 190. 7, Globigerinoides elongatus (d'Orbigny, 1826), umbilical view of specimen from sample CA-26 of the Stilo section, unnamed formation, Pleistocene, x 230. 8, Orbulina bilobata d'Orbigny, 1846, umbilical view of specimen from sample CA-23 of the Stilo section, unnamed formation, early Pliocene, x 170. 9, Orbulina universa d'Orbigny, 1839b, umbilical view of specimen from sample CA-27 of the Stilo section, unnamed formation, Pleistocene, x 190.

FIGURE 12-1, Paragloborotalia acrostoma Wezel, 1966, view of umbilical side of specimen from sample CA-70 of the Bova section, Stilo-Capo d'Orlando Formation, early Miocene, x 160. 2, Globorotalia puncticulata (Deshayes, 1832), umbilical view of specimen from sample CA-106 of the Stignano section, unnamed formation, early Pliocene, x 130. 3, Globorotalia inflata d'Orbigny, 1839a, umbilical view of specimen from sample CA-28 of the Stilo section, unnamed formation, Pleistocene, x 170. 4, Globorotalia scitula (Brady in Tizard and Murray, 1882), umbilical view of specimen from sample CA-95, of the Stignano Section, unnamed formation, middle Miocene, x 370. 5, 6, Globorotalia margaritae Bolli and Bermuidez, 1965. 5, umbilical view of specimen from sample CA-24 of the Stilo section, unnamed formation, early Pliocene, x 180; 6, dorsal view of same specimen x 180. 7, Truncorotalia truncatulinoides (d'Orbigny, 1839a), umbilical view of specimen from sample CA-28 of the Stilo section, unnamed formation, Pleistocene, x 160. 8, Catapsydrax dissimilis (Cushman and Bermudez, 1937), umbilical view of specimen from sample CA-50, of the Monte Tronato section, Stilo-Capo d'Orlando Formation, early Miocene, x 300. 9, Hastigerina aequilateralis (Brady, 1879), umbilical view of specimen from sample CA-26 of the Stilo section, unnamed formation, Pleistocene, x200. 10, Dentoglobigerina baroemoenensis (LeRoy, 1939), umbilical view of specimen from sample CA-96, of the Stignano Section, unnamed formation, middle Miocene, x 170.

14




-..,., '

.: . '' , *.

, ,. - --.. . .. ; /

. - . v;'~^. U*.

t >1

15

J . " . ,

. I -* i t- .1F . . I,: ' _.a v.e Ik ." . A .



16 JOURNAL OF PALEONTOLOGY, V. 69, NO. 1, 1995

9~~~"?~l~



17 PATTERSON ET AL. -OLIGOCENE-PLEISTOCENE SEQUENCE IN ITALY

..- .-. '

r >%

VA:^ a*lfel Fr

~ = i: 4

iS?"CC-tY-i`,,r --??.? :. r?rL*CTII1 ? .,*. ... . '?-,? 4 (?? ?C?. iT:.?. c 'r.

?=.. ...:r,.lr ?? ;?i;?r :'???; ;',;?? = ?;?* .,-. -?-?,'"-

?? "




REFERENCES

AFCHAIN, C. 1966. La base de la s6rie tertiaire sur le bord oriental de la Calabre ulterieure. C. R. Somm. Soci&et Geologique France, 10: 397-398.

ALVAREZ, W., T. COCOZZA, AND F. C. WEZEL. 1974. Fragmentation of the Alpine orogenic belt by microplate dispersal. Nature, 248:309- 314.

AMODIO-MORELLI, L., G. BONARDI, V. COLONNA, D. DIETRICH, G. GIUNTA, F. IPPOLITO, V. LIGUORI, S. LORENZONI, A. PAGLIONICO, V. PERRONE, G. PICCARRETA, M. Russo, P. SCANDONE, E. ZANETTIN-LORENZONI, AND A. ZUPPETTA. 1976. L'arco calabro-peloritano nell'orogene appenninico-magrebide. Memorie Societa' Geo- logica Italiana, 17:1-60.

ANDERSSON, P. S., G. J. WASSERBURG, AND J. INGRI. 1993. The source and transport of Sr and Nd Isotopes in the Baltic Sea. Earth and Planetary Science Letters, 113:459-472.

BARRIER, P., AND C. MONTENAT. 1987. Essai de quantification des mouvements verticaux plio-pleistocenes dans le Detroit de Messine (Italie). Notes and Memoires, Total Compagnie Francaise des Pe- troles, 21:73-79.

BLOW, W. H. 1959. Age, correlation, and biostratigraphy of the upper Tocuyo (San Lorenzo) and Poz6n Formations, eastern Falc6n, Ven- ezuela. Bulletins of American Paleontology, 39:67-252.

BOLLI, H. M. 1954. Note on Globigerina concinna REUSS, 1850. Contributions from the Cushman Foundation for Foraminiferal Re- search, 5:1-3.

1957. Planktonic foraminifera from the Miocene Cipero and Lengua Formations of Trinidad, B.W.I., p. 97-123. In A. R. Loeblich, Jr., and collaborators, Studies of Foraminifera; Part 1-Planktonic Foraminifera. U.S. National Museum, Bulletin 215.

-, AND P. J. BERMUDEZ. 1965. Zonation based on planktonic foraminifera of Middle Miocene to Pliocene warm-water sediments. Bolletin Informativo, Asociation Venezolana de Geologia, Mineria y Petroleo, 8:119-149.

-, AND J. B. SAUNDERS. 1985. Oligocene to Holocene low-latitude planktic foraminfera, p. 155-262. In H. M. Bolli, J. B. Saunders, and K. Perch-Nielsen, Plankton Stratigraphy, Volume 1, Planktic Fora- minifera, Calcareous Nannofossils and Calpionellids. Cambridge Earth Science Series.

BONARDI, G., G. GIUNTA, V. PERRONE, M. Russo, A ZUPPETTA, AND G. CIAMPO. 1980. Osservazioni sull'evoluzione dell'arco calabro- peloritano nel Miocene inferiore: la Formazione di Stilo-Capo d'Or- lando. Bollettino Societa Geologica Italiana, 99:365-393.

-, T. PESCATORE, P. SCANDONE, AND M. TORRE. 1971. Problemi paleogeografici connessi con la successione mesozoico-terziaria di Stilo (Calabria meridionale). Bollettino Societa Naturalisti Napoli, 80:1- 14.

BRADY, H. B. 1877. Supplementary note on the foraminifera of the chalk(?) of the New Britain group. Geological Magazine, New Series, Decade 2, 4:534-536.

1879. Notes on some of the reticularian Rhizopoda of the "Chal- lenger" Expedition; Part II, Additions to the knowledge of porcellan- ous and hyaline types. Quarterly Journal of Microscopical Science, London, New Series, 19:261-299.

CASSA PER IL MEZZOGIORNO. 1968-1972. Geologic Map of Calabria, scale 1:25,000. Poligrafica & Cartevalori, Ercolano (Naples).

CAVAZZA, W. 1989. Detrital modes and provenance of the Stilo-Capo d'Orlando Formation (Miocene), southern Italy. Sedimentology, 37: 1077-1090.

1992. Sandstone and conglomerate petrofacies reflect the late Cenozoic geodynamics of the Calabrian microplate, southern Italy. Abstract Book, 29th International Congress, Kyoto, Japan, 302 p.

-, AND J. DAHL. 1990. Note on the temporal relationships between precipitation of authigenic minerals and sandstone compaction. Sed- imentary Geology, 69:37-44.

-, AND P. G. DECELLES. 1993. Geometry of a Miocene submarine canyon and associated sedimentary facies in southeastern Calabria, southern Italy. Geological Society of America Bulletin, 105:1297- 1309.

CHANNELL, J. E. T., D. Rio, AND R. C. THUNELL. 1988. Miocene- Pliocene boundary magnetostratigraphy at Capo Spartivento, Cala- bria, Italy. Geology, 16:1096-1099.

CHAPMAN, F., W. J. PARR, AND A. C. COLLINS. 1934. Tertiary foraminifera of Victoria, Australia. The Balcombian deposits of Port Philip; Part III. Linnean Society of London, Journal of Zoology, 38(1932-1934):533-577.

CITA, M. B. 1975. The Miocene-Pliocene boundary: history and definition, p. 1-30. In T. Saito and L. H. Burckle (eds.), Late Neogene Epoch Boundaries. Micropaleontology Special Publications, 1.

COURME, M. D., AND G. MASCLE. 1988. Nouvelles donnees strati- graphiques sur les series Oligo-Miocenes des unites Siciliennes: con- sequences paleog6ographiques. Bulletin Societe G6ologique France, 1:105-118.

CRESCENTI, U. 1966. Sulla biostratigrafia del Miocene affiorante al confine marchigiano-abruzzese. Geologica Romana, Rome, 5:1-54.

CUSHMAN, J. A., AND P. J. BERMUDEZ. 1937. Further new species of foraminifera from the Eocene of Cuba. Contributions from the Cush- man Laboratory for Foraminiferal Research, 13:1-29.

, AND P. W. JARvis. 1936. Three new foraminifera from the Mio- cene Bowden marl of Jamaica. Contributions from the Cushman Laboratory for Foraminiferal Research, 12:3-5.

DEPAOLO, D. J. 1986. Detailed record of the Neogene Sr isotopic evolution of seawater from DSDP Site 590B. Geology, 14:103-106.

, AND B. L. INGRAM. 1985. High resolution stratigraphy with strontium isotopes. Science, 227:938-941.

DERCOURT, J. ET AL. (17 authors). 1985. Presentation de 9 cartes paleog6ographiques au 1/20.000.000 s'etendant de l'Atlantique au Pamir pour la periode du Lias i l'Actuel. Bulletin Societe Geologique France, 5:637-652.

DESHAYES, G. P. 1832. Encyclopedie methodique. Histoire naturelle des vers, Mme. v. Agasse, 2:1-594.

DEVISSER, J. P., J. EBBING, L. GUDJONSSON, F. HILGEN, F. JORISSEN, P. VERHALLEN, AND D. ZEVENBOOM. 1989. The origin of the rhythmic bedding in the Pliocene Trubi Formation of Sicily, southern Italy. Palaeogeography, Palaeoclimatology, Palaeoecology, 69:45-66.

DEWEY, J. F., M. L. HELMAN, E. TURCO, D. H. W. HUTTON, AND S. D. KNOTT. 1989. Kinematics of the western Mediterranean, p. 265- 283. In M. P. Coward, D. Dietrich, and R. G. Park, Alpine Tectonics. Geological Society, Special Publication 45.

-, W. C. PITMAN, W. B F. RYAN, AND J. BONNIN. 1973. Plate tectonics and the evolution of the Alpine system. Geological Society of America Bulletin, 84:3137-3180.

EDMOND, J. M. 1992. Himalayan tectonics, weathering processes, and the strontium isotope record in the marine limestones. Science, 258: 1594-1597.

EGGER, J. G. 1893. Foraminiferen aus Meeresgrundproben, gelothet von 1874 bis 1876 von S. M. Sch. Gazelle. (K.) Bayerischen Akademie der Wissenschaften, Mathematisch-Physikalischen Klasse, Abhand- lungen, Sitzungsberichte, Miinchen, 18:193-458.

EHRENBERG, C. G. 1861. Elemente des tiefen Meeresgrundes im Mexi- kanischen Golfstrome bei Florida; Uber die Tiefgrund-Verhiiltnisse des Oceans am Eingange der Davisstrasse und bei Island. (K.) Preuss. Akademie der Wissenschaften, Physikalisch-Mathematischen Klasse, Bericht, Monatsberichte, Berlin, 275-315.

FAURE, G. 1982. The marine-strontium geochronometer, p. 73-79. In G. S. Odin, Numerical Dating in Stratigraphy, Volume 1. John Wiley and Sons, New York.

1986. Principles of Isotope Geology. John Wiley and Sons, New York, 589 p.

GORLER, K. 1978. Neogene olistostromes in southern Italy as an in- dicator of contemporaneous plate tectonics, p. 355-359. In H. Closs, D. Roeder, and K. Schmidt (eds.), Alps, Apennines, Hellenides. Inter- Union Commission on Geodynamics, Scientific Report 38.

GUDJONSSON, L., AND G. J. VAN DER ZWAAN. 1985. Anoxic events in the Pliocene Mediterranean: stable isotope evidence of run-off. Pro- ceedings of the Koninklijke Nederlandse Akademie van Wetenschap- pen, B, 88:69-82.

HESSE, J., M. L. BENDER, AND J. G. SCHILLING. 1986. Evolution of the ratio of strontium-87 to strontium-86 in sea water from Cretaceous to present. Science, 231:979-984.

HILGEN, F. J. 1987. Sedimentary rhythms and high-resolution chrono- stratigraphic correlations in the Mediterranean Pliocene. Stratigraphy Newsletter, 17:109-127.

HODELL, D. A., P. A. MUELLER, AND J. R. GARRIDO. 1991. Variations

18




in the strontium isotopic composition of seawater during the Neogene. Geology, 19:24-27.

HURST, R. W. 1986. Strontium isotopic chronostratigraphy and correlation of the Miocene Monterey Formation in the Ventura and Santa Maria Basins of California. Geology, 14:459-462.

IACCARINO, S. 1985. Mediterranean Miocene and Pliocene planktic foraminifera, p. 283-314. In H. M. Bolli, J. B. Saunders, and K. Perch-Nielsen (eds), Plankton Stratigraphy, Volume 1, Planktic Fo- raminifera, Calcareous Nannofossils and Calpionellids. Cambridge Earth Science Series.

JENKINS, D. G. 1960. Planktonic foraminifera from the Lakes Entrance oil shaft, Victoria, Australia. Micropaleontology, 6:345-371.

KENNETT, J. P., AND M. S. SRINIVASAN. 1983. Neogene Planktonic Foraminifera: A Phylogenetic Atlas. Hutchinson Ross Publishing Company, Stroudsburg, Pennsylvania, 265 p.

KOEPNICK, R. B., R. E. DENISON, AND D. A. DAHL. 1988. The Cenozoic 87Sr/86Sr curve: data review and implications for correlation of marine strata. Paleoceanography, 3:743-756.

LEROY, L. W. 1939. Some small foraminifera, ostracoda and otoliths from the Neogene (Miocene) of the Rokan-Tapanoeli area, central Sumatra. Natuurkundig Tijdschrift voor Nederlandsch-Indie, Bata- via, 99:215-296.

LOEBLICH, A. R., JR., AND H. TAPPAN. 1987. Foraminiferal genera and their classification. Van Nostrand, Reinhold Co., New York (2 vols.), 2,047 p.

MALINVERNO, A., AND W. B. F. RYAN. 1986. Extension in the Tyr- rhenian Sea and shortening in the Apennines as result of arc migration driven by sinking in the lithosphere. Tectonics, 5:227-245.

MCKENZIE, J. A., D. A. HODELL, P. A. MUELLER, AND D. W. MUELLER. 1986. Application of strontium isotopes to late Miocene-early Plio- cene stratigraphy. Geology, 16:1022-1025.

MEULENKAMP, J. E., F. HILGEN, AND E. VOOGT. 1986. Late Cenozoic sedimentary-tectonic history of the Calabrian Arc. Giornale di Geo- logia, 48:345-359.

MILLER, K. G., M. D. FEIGENSON, D. V. KENT, AND R. K. OLSSON. 1988. Upper Eocene to Oligocene isotope (87Sr/86Sr, 6b80, 613C) standard section, Deep Sea Drilling Project 522. Paleoceanography, 3:223- 233.

MILLER, K. G., M. D. FEIGENSON, J. D. WRIGHT, AND B. M. CLEMENT. 1991. Miocene isotopic reference section, Deep Sea Drilling Project Site 608: an evaluation of isotope and biostratigraphic resolution. Paleoceanography, 6:33-52.

MINZONI, N., A. GARAVELLO, V. LUCIANI, A. NEGRI, AND S. UNGARO. 1992. La Calabria ercinica negli orogeni alpino e appenninico-ma- ghrebide. Bollettino Societa Geologica Italiana, 111:131-145.

NATLAND, M. L. 1938. New species of foraminifera off the west coast of North America and from the later Tertiary of the Los Angeles Basin. University of California, Scripps Institution of Oceanography Bulletin, 4:137-164.

ORBIGNY, A. D. D'. 1826. Tableau methodique de la classe des Ce- phalopodes. Annales des Sciences Naturelles, Paris, France, Series 1, 7:96-314.

1839a. Foraminiferes des iles Canaries, p. 119-146. In P. Barker- Webb and S. Berthelot (eds.), Histoire Naturelle des iles Canaries. Bethune, 2 (Zoology).

1839b. Foraminiferes, p. 1-224. In R. de la Sagra (ed.), Histoire physique, politique et naturelle de l'ile de Cuba. A. Bertrand, Paris, 8.

- 1846. Foraminiferes fossiles du bassin Tertiare de Vienne (Au- triche) (Die fossilen Foraminiferen des Tertiaren Beckens von Wien). Gide et Comp., Paris, France, 303 p.

RAYMO, M. E., AND W. F. RUDDIMAN. 1992. Tectonic forcing of late Cenozoic climate. Nature, 359:117-122.

, and P. N. Froelich. 1988. Influence of late Cenozoic moun- tain building on ocean geochemical cycles. Geology, 16:649-653.

REUSS, A. E. 1850. Neues Foraminiferen aus den Schichten des Os- terreichischen Tertiarbeckens. Denkschriften der Kaiserlichen Aka- demie der Wissenschaften, Mathematisch-Naturwissenschaftlichen Klasse, Wien, 1:365-390.

Rio, D., R. SPROVIERI, AND R. THUNELL. 1991. Pliocene-lower Pleis- tocene chronostratigraphy: a re-evaluation of Mediterranean type sections. Geological Society of America Bulletin, 103:1049-1058.

RODA, C. 1965. II calcare portlandiano a Dasycladacee di M. Mutolo, Reggio Calabria. Geologica Romana, 4:259-290.

RUNDBERG, Y., AND P. C. SMALLEY. 1989. High-resolution dating of Cenozoic sediments from northern North Sea using 87Sr/86Sr stratigraphy. American Association of Petroleum Geologists Bulletin, 73: 298-308 (see also discussion and reply, 74:1283-1290).

SCHWAGER, C. 1866. Fossile Foraminiferen von Kar Nikobar, p. 187- 268. In Reise der Osterreichischen Fregatte Novara um die Erde in den Jahren 1857, 1858, 1859, unter den Befehlen des Commodore B. von Wullerstorf-Urbair. Geologischer Theil, 2 (no. 1, Geologische Beobachtungen, no. 2, Paliiontologische Mittheilungen.

STOW, D. A. V., D. G. HOWELL, AND C. H. NELSON. 1985. Sedimentary, tectonic and sea-level controls, p. 15-22. In A. H. Bouma, W. R. Normark, and N. E. Barnes (eds.), Submarine Fans and Related Tur- bidite Systems. Springer Verlag, New York.

THUNELL, R., D. Rio, R. SPROVIERI, AND I. RAFFI. 1992. Limestone- marl couplets: origin of the early Pliocene Trubi marls in Calabria, southern Italy. Journal of Sedimentary Petrology, 61:1109-1122.

TIZARD, STAFF COMMANDER, AND J. MURRAY. 1882. Exploration of the Far6e Channel during the summer of 1880, in Her Majesty's hired Ship "Knight Errant." Royal Society of Edinburgh, Proceedings, Ed- inburgh, 11(1880-1882):638-720.

VEIZER, J., 1989. Strontium isotopes in sea water through time. Annual Review of Earth and Planetary Sciences, 17:141-168.

WELTJE, G. 1992. Oligocene to Early Miocene sedimentation and tectonics in the southern part of the Calabrian-Peloritan Arc (Aspro- monte, southern Italy): a record of mixed-mode piggy-back basin evolution. Basin Research, 4:37-68.

WEZEL, F. C. 1966. Nuova specie dell'Oligomiocene italiano. Rivista Italiana di Paleontologia, 87:1298-1306.

ZUDERVELD, J. D. A., F. J. HILGEN, C. G. LANGEREIS, P. J. J. M. VER- HALLEN, AND J. W. ZACHARIASSE. 1991. Integrated magnetostratigraphy and biostratigraphy of the upper Pliocene-lower Pleistocene from the Monte Singa and Crotone areas in Calabria, Italy. Earth and Planetary Science Letters 107:697-714.

-, J. W. ZACHARIASSE, P. J. J. M. VERHALLEN, AND F. J. HILGEN. 1986. The age of the Miocene-Pliocene boundary. Stratigraphy Newsletter, 16:169-181.

ACCEPTED 1 JANUARY 1994

APPENDIX

FAUNAL LIST

Species are listed alphabetically. Generic assignment variously follows Bolli and Saunders (1985), Iaccarino (1985), Loeblich and Tappan (1987), and Kennett and Srinivasan (1983). As the nature of this paper is not taxonomic and to reduce space, full species synonymies are not provided. Where the original generic designation varies from present usage, the original is provided in square brackets.

Catapsydrax dissimilis (Cushman and Bermfidez, 1937), [Globigerina], Figure 12.8

Dentoglobigerina altispira altispira (Cushman and Jarvis, 1936), [Glo- bigerina], Figure 10.11

Dentoglobigerina baroemoenensis (LeRoy, 1939), [Globigerina], Figure 12.10

Globigerina bulloides d'Orbigny, 1826, Figure 11.6 Globigerina ciperoensis Bolli, 1954, Figure 11.9 Globigerina quinqueloba Natland, 1938, Figure 11.8 Globigerina woodi Jenkins, 1960, Figure 11.5 Globigerinoides bulloideus Crescenti, 1966, Figure 12.3 Globigerinoides elongatus (d'Orbigny, 1826), [Globigerina], Figure 12.7 Globigerinoides extremus Bolli and Bermidez, 1965, [Globigerinoides

obliquus Bolli subsp.], Figure 11.5 Globigerinoides obliquus Bolli, 1957, Figure 12.6 Globigerinoides quadrilobatus (d'Orbigny, 1846), [Globigerina], Figure

12.2 Globigerinoides sacculifer (Brady, 1877), [Globigerina], Figure 11.4 Globigerinoides triloba (Reuss, 1850), [Globigerina], Figure 11.1 Globoquadrina dehiscens (Chapman, Parr, and Collins, 1934), [Globoro-

talia], Figure 10.10 Globorotalia inflata (d'Orbigny, 1839a), [Globigerina], Figure 12.3

19



JOURNAL OF PALEONTOLOGY, V 69, NO. 1, 1995 JOURNAL OF PALEONTOLOGY, V 69, NO. 1, 1995

Globorotalia margaritae Bolli and Bermfidez, 1965, Figure 12.5, 6 Globorotalia puncticulata (Deshayes, 1832), [Globigerina], Figure 12.2 Globorotalia scitula (Brady in Tizard and Murray, 1882), [Pulvinulina],

Figure 12.4 Hastigerina aequilateralis (Brady, 1879), [Globigerina], Figure 12.9 Neogloboquadrina acostaensis (Blow, 1959), [Globorotalia], Figure 10.4 Neogloboquadrina dutertrei (d'Orbigny, 1839b), [Globigerina], Figure

10.3 Neogloboquadrina pachyderma (Ehrenberg, 1861), [Aristerospira], Fig-

ure 10.2

Globorotalia margaritae Bolli and Bermfidez, 1965, Figure 12.5, 6 Globorotalia puncticulata (Deshayes, 1832), [Globigerina], Figure 12.2 Globorotalia scitula (Brady in Tizard and Murray, 1882), [Pulvinulina],

Figure 12.4 Hastigerina aequilateralis (Brady, 1879), [Globigerina], Figure 12.9 Neogloboquadrina acostaensis (Blow, 1959), [Globorotalia], Figure 10.4 Neogloboquadrina dutertrei (d'Orbigny, 1839b), [Globigerina], Figure

10.3 Neogloboquadrina pachyderma (Ehrenberg, 1861), [Aristerospira], Fig-

ure 10.2

Orbulina bilobata d'Orbigny, 1846, Figure 11.8 Orbulina universa d'Orbigny, 1839b, Figure 11.9 Paragloborotalia acrostoma (Wezel, 1966), [Globorotalia], Figure 12.1 Paragloborotalia nana (Bolli, 1957), [Globorotalia], Figure 10.1 Sphaeroidinellopsis seminulina seminulina (Schwager, 1866), [Globi-

gerina], Figure 10.12 Tinophodella glutinata (Egger, 1893), [Globigerina], Figure 10.7 Truncorotalia truncatulinoides (d'Orbigny, 1839a), [Rotalia], Figure 12.7

Orbulina bilobata d'Orbigny, 1846, Figure 11.8 Orbulina universa d'Orbigny, 1839b, Figure 11.9 Paragloborotalia acrostoma (Wezel, 1966), [Globorotalia], Figure 12.1 Paragloborotalia nana (Bolli, 1957), [Globorotalia], Figure 10.1 Sphaeroidinellopsis seminulina seminulina (Schwager, 1866), [Globi-

gerina], Figure 10.12 Tinophodella glutinata (Egger, 1893), [Globigerina], Figure 10.7 Truncorotalia truncatulinoides (d'Orbigny, 1839a), [Rotalia], Figure 12.7


THE TYPE SPECIES OF STICTOSTROMA PARKS, 1936 (PORIFERA, STROMATOPOROIDEA)

COLIN W. STEARN Earth and Planetary Sciences, McGill University, 3450 University St.,

Montreal, QC., H3A 2A7, Canada

ABSTRACr-The typical species of Parks' stromatoporoid genus Stictostroma designated as Stromatopora mammillata Nicholson, 1873, and renamed S. mamilliferum to avoid homonymy by Galloway and St. Jean (1957), had unknown internal structure because Nicholson's type specimens were not sectioned. Parks' (1936) diagnosis of generic characters was based on specimens from a location (Gorrie) far from the type locality of S. mammillata that he assumed were conspecific with Nicholson's species. Investigation of the type specimens ofStromatopora mammillata = Stictostroma mamilliferum by thin sections shows that they are very poorly preserved and not conspecific with the specimens on which Parks based the genus. Because paleontologists for many years have used Stictostroma as amended from Parks' description by Galloway and St. Jean, the species from Gorrie that clearly shows these characters should be recognized as the typical species and given a new name.


THE TYPE SPECIES OF STICTOSTROMA PARKS, 1936 (PORIFERA, STROMATOPOROIDEA)

COLIN W. STEARN Earth and Planetary Sciences, McGill University, 3450 University St.,

Montreal, QC., H3A 2A7, Canada

ABSTRACr-The typical species of Parks' stromatoporoid genus Stictostroma designated as Stromatopora mammillata Nicholson, 1873, and renamed S. mamilliferum to avoid homonymy by Galloway and St. Jean (1957), had unknown internal structure because Nicholson's type specimens were not sectioned. Parks' (1936) diagnosis of generic characters was based on specimens from a location (Gorrie) far from the type locality of S. mammillata that he assumed were conspecific with Nicholson's species. Investigation of the type specimens ofStromatopora mammillata = Stictostroma mamilliferum by thin sections shows that they are very poorly preserved and not conspecific with the specimens on which Parks based the genus. Because paleontologists for many years have used Stictostroma as amended from Parks' description by Galloway and St. Jean, the species from Gorrie that clearly shows these characters should be recognized as the typical species and given a new name.

INTRODUCTION

WHEN PARKS (1936) established the genus Stictostroma he suggested that it might be characterized by two type

species (cogenotypes) with different characters: Stromatopora mammillata Nicholson and Stictostroma eriense Parks. The genus was established to include species that resemble Stroma- toporella Nicholson, a genus that has ring-pillars and cellular laminae. Parks suggested that species that had only one of these two features could be placed in Stictostroma. The group with ring-pillars but without cellular laminae was typified by S. eriense, and the group with cellular laminae but no ring-pillars was typified by S. mammillatum. The procedure was criticized by paleontologists (e.g., Lecompte, 1951) who rejected the genus because its proposal was not according to the Code of Zoological Nomenclature. To resolve this unfortunate situation Galloway and St. Jean (1957) referred Stictostroma eriense to Stromato- porella, renamed Stromatopora mammillata Nicholson Stic- tostroma mamilliferum because Stromatopora mammillata Nicholson, 1873, was preoccupied by Stromatopora mammillata Schmidt, 1858, and established Stromatopora mammillata = Stictostroma mamilliferum as the type species. Since then the concept of the genus that Parks conceived as typified by S. mammillata = S. mamilliferum has been used by many workers to establish many species, that is, a stromatoporoid with cellular laminae but simple post-pillars and few, if any, ring-pillars.

Parks' concept of the characteristics of S. mammillatum was not based on Nicholson's type specimens from Port Colborne, Ontario, but on specimens that he assumed to be conspecific from Ashton's Quarry at the village of Gorrie, Ontario, about 100 km to the northwest. There is no way in which Parks could

INTRODUCTION

WHEN PARKS (1936) established the genus Stictostroma he suggested that it might be characterized by two type

species (cogenotypes) with different characters: Stromatopora mammillata Nicholson and Stictostroma eriense Parks. The genus was established to include species that resemble Stroma- toporella Nicholson, a genus that has ring-pillars and cellular laminae. Parks suggested that species that had only one of these two features could be placed in Stictostroma. The group with ring-pillars but without cellular laminae was typified by S. eriense, and the group with cellular laminae but no ring-pillars was typified by S. mammillatum. The procedure was criticized by paleontologists (e.g., Lecompte, 1951) who rejected the genus because its proposal was not according to the Code of Zoological Nomenclature. To resolve this unfortunate situation Galloway and St. Jean (1957) referred Stictostroma eriense to Stromato- porella, renamed Stromatopora mammillata Nicholson Stic- tostroma mamilliferum because Stromatopora mammillata Nicholson, 1873, was preoccupied by Stromatopora mammillata Schmidt, 1858, and established Stromatopora mammillata = Stictostroma mamilliferum as the type species. Since then the concept of the genus that Parks conceived as typified by S. mammillata = S. mamilliferum has been used by many workers to establish many species, that is, a stromatoporoid with cellular laminae but simple post-pillars and few, if any, ring-pillars.

Parks' concept of the characteristics of S. mammillatum was not based on Nicholson's type specimens from Port Colborne, Ontario, but on specimens that he assumed to be conspecific from Ashton's Quarry at the village of Gorrie, Ontario, about 100 km to the northwest. There is no way in which Parks could

have known the diagnostic internal structures of Stromatopora mammillata Nicholson, because the type specimen was appar- ently never sectioned by Nicholson and was illustrated only by its external surface (1873, 1874; Nicholson and Murie, 1878). Parks' genus was, therefore, based on a type species whose internal structure was unknown.

In this paper I examine Nicholson's type material of Sticto- stroma mamilliferum Galloway and St. Jean, compare it with Parks' types from Gorrie on which the concept of the genus Stictostroma Parks was established, conclude that they cannot be shown to be conspecific, and propose to petition the Inter- national Commission on Zoological Nomenclature that Stro- matopora mammillata Nicholson be invalidated as the typical species of the genus Stictostroma Parks and that a specimen of Parks from Gorrie be accepted as type specimen of the generic type species that must have a new species name.

HISTORICAL SUMMARY

Schmidt (1858) used the name Stromatopora mammillata for an Ordovician stromatoporoid from Estonia. It has been now assigned to Clathrodictyon by Nestor (1964), who gave a com- plete synonymy. Galloway and St. Jean's (1957) proposal of S. mamilliferum cleared this problem of homonyms.

The name was also used by Bigsby (1868, p. 194) for a stromatoporoid from "L. Silur (top) (L. Huron) Manit. Isl." where it is attributed to "Bell." Fliigel and Fliigel-Kahler (1968) suggested that "Bell." may be a mispelled abbreviation for Billings, but the period after authors' names in Bigsby's lists does not always indicate an abbreviation. In any case, this usage is invalid as the name was preoccupied.

have known the diagnostic internal structures of Stromatopora mammillata Nicholson, because the type specimen was appar- ently never sectioned by Nicholson and was illustrated only by its external surface (1873, 1874; Nicholson and Murie, 1878). Parks' genus was, therefore, based on a type species whose internal structure was unknown.

In this paper I examine Nicholson's type material of Sticto- stroma mamilliferum Galloway and St. Jean, compare it with Parks' types from Gorrie on which the concept of the genus Stictostroma Parks was established, conclude that they cannot be shown to be conspecific, and propose to petition the Inter- national Commission on Zoological Nomenclature that Stro- matopora mammillata Nicholson be invalidated as the typical species of the genus Stictostroma Parks and that a specimen of Parks from Gorrie be accepted as type specimen of the generic type species that must have a new species name.

HISTORICAL SUMMARY

Schmidt (1858) used the name Stromatopora mammillata for an Ordovician stromatoporoid from Estonia. It has been now assigned to Clathrodictyon by Nestor (1964), who gave a com- plete synonymy. Galloway and St. Jean's (1957) proposal of S. mamilliferum cleared this problem of homonyms.

The name was also used by Bigsby (1868, p. 194) for a stromatoporoid from "L. Silur (top) (L. Huron) Manit. Isl." where it is attributed to "Bell." Fliigel and Fliigel-Kahler (1968) suggested that "Bell." may be a mispelled abbreviation for Billings, but the period after authors' names in Bigsby's lists does not always indicate an abbreviation. In any case, this usage is invalid as the name was preoccupied.

20 20



Documents

PLANKTIC FORAMINIFERAL BIOSTRATIGRAPHY AND 87Sr/86Sr ... · logical descriptions rare, except for a few Pliocene-Pleistocene stratigraphic sections of limited thickness (e.g., Zijderveld