Reworked latest () and Early from the Late of the Amadeus Basin, central Australia

ROBERT S. NICOLL, JOHN R. LAURIE, ANDREW KELMAN & JOHN D. GORTER

NICOLL, R.S., LAURIE, J.R., KELMAN, A. & GORTER, J.D., 2007:12:21. Reworked latest Cambrian (Furongian) and Early Ordovician conodonts from the Late Devonian of the Amadeus Basin, central Australia. Memoirs of the Association of Australasian Palaeontologists 34, 545-554. ISSN 0810-8889.

A fauna of reworked conodonts from a lithic sandstone in the Ellery Creek Fan of the Late Devonian Brewer Conglomerate comprises mostly unidentifiable, elongate, rounded fragments indicating erosion to discrete grain particles prior to redeposition. The fauna is of mixed age, consisting of Early Ordovician (Aloxoconus iowaensis) and Furongian, latest Cambrian, (Hirsutodontus simplex) elements implying sourcing from multiple stratigraphic units. The latter species has not been recovered previously from the Amadeus Basin despite extensive sampling of Cambro-Ordovician units. Another small fauna obtained from a large limestone clast from a conglomerate in the Late Devonian Hermannsburg Sandstone includes Oepikodus cleftus, previously recorded from the lower part of the Early Ordovician Horn Valley Siltstone. These conodonts suggest that the northern depositional edge of the Amadeus Basin lay far to the north of the present structural and erosional northern margin of the basin. The elements have a conodont color alteration index (CAI) of 1 indicating that they have never been deeply buried, either originally or after reworking.

Robert S. Nicoll, Department of Earth and Marine Science, Australian National University, Canberra ACT 0200; John R. Laurie, Andrew Kelman, Geoscience Australia, GPO Box 378 Canberra, ACT 2601, Australia; John D. Gorter, Eni Australia Limited, PO Box 1265, West Perth, WA 6005, Australia. Received 19 November 2007.

Keywords: Devonian, Late Cambrian, Early Ordovician, conodont, reworking, Amadeus Basin.

THE DEVONIAN Parke Siltstone, Hermannsburg Conglomerate represents the culmination of Sandstone and Brewer Conglomerate of the the Alice Springs Orogeny (Jones 1991). Dated Pertnjara Group represent the foredeep molasse as Late Devonian (Frasnian) by Playford et deposits of the Alice Springs Orogeny in the al. (1976), the 3100 m thick unit thins rapidly Amadeus Basin. These units include reworked southward into the Missionary Trough (Jones sediments that had been initially deposited 1991). The Ellery Creek Fan, one of several north of the present basin margin before being distinct fanglomerates on the northern margin rapidly stripped and transported south to the has been noted as containing abundant Cambrian basin foredeep. Clasts from within the molasse and Ordovician clasts in its lower part (Jones were derived from rocks of the Arunta basement 1972, 1991). complex up to at least the Early Ordovician The deposition of the Pertnjara Group in the Horn Valley Siltstone and probably the Middle Amadeus Basin (Jones 1991) was initiated by a Ordovician Stairway Sandstone, Stokes Siltstone sequence of tectonic uplifts to the north of the and the ? Mereenie Sandstone. present basin margin in which progressively The present northern edge configuration of older sediments were stripped from the now the Amadeus Basin is not depositional, but the removed, uplifted northern part of the basin and result of uplift during the Alice Springs Orogeny redeposited over the central part of the basin. (Lindsay & Korsch 1991). On the eroded edge of This destruction effectively now masks the the steeply southward dipping northern margin depositional configuration of the Amadeus Basin of the present Amadeus Basin, the Brewer in Cambrian and Ordovician time. 546 AAP Memoir 34 (2007)

Fig. 1. Locality map of the Ellery Creek sample locality showing geology. Filled ellipses are probable source levels in the Pacoota Sandstone (i.e. seq 2 from sequence 2; seq 3 from sequence 3). Open elipse (HV) is probable source level within the lower part of the Horn Valley Siltstone. Open square (Herm) is the locality of the sample in the Hermannsburg Sandstone (JG 2005-1) from which conodonts from the Horn Valley Siltstone were obtained. Filled squares are samples obtained by Tingate (1990; 44 = 8351-44; 45 = 8351-45; 46a = 8351-46a) containing conodonts from the Pacoota Sandstone. Rock unit symbols are listed in Figure 2.

This work documents the conodont SAMPLING faunas obtained from samples taken from The reworked conodonts used in this study were the Hermannsburg Sandstone and Brewer obtained from four samples from the Brewer Conglomerate and discusses the implications of Conglomerate and Hermannsburg Sandstone the reworking of these conodonts for the tectonic in the Ellery Creek section in the Amadeus history and depositional extent of the Amadeus Basin. Comparative material was obtained from Basin. Sequence 3 of the Pacoota Sandstone in the same section and from the Jiggamore Member AAP Memoir 34 (2007) 547

Brewer Conglomerate Db Sample Taxon N Hermannsburg Sandstone De 8351-44 gen. et sp. indet. 2 Hirsutodontus simplex 1 Parke Siltstone Dj Pertnjara Gp Pertnjara Aloxoconus iowaensis 1 Devonian Drepanodus sp. 3 Mereenie Sandstone Pzm 8351-45 Drepanodus ? sp. 3 Sil. Scolopodus sp. 5 Ulrichodina sp. 1 indet. coniform elements 47 Drepanodus ? sp. 1 Os Stairway Sandstone 8351-46a Scolopodus ? sp. 1 Horn Valley Siltstone Oh indet. coniform elements 14 Ordovician Sequence 4 P 17 Sequence 3 Oepikodus cleftus Pacoota S 36 ЄOp P 157 Sandstone Sequence 2 Oepikodus communis S 131 Sequence 1 M 52 Pa 3 Jumudontus gananda Upper Goyder Formation Єg JG 2005-1 Pb 1 Bergstroemognathus kirki 6 Lower Goyder Formation Єg S,M 32 Cooperignathus nyinti Pa 3 Jay Creek Limestone Єj Pb 2 Cornuodus longibasis 39

Cambrian indet. coniform elements 357 Table 1. Reworked Ordovician and Cambrian Hugh River Shale Єh conodonts from the Devonian Brewer Conglomerate and Hermannsburg Sandstone, Ellery Creek, Amadeus Basin. N refers to number of elements. preserved conodonts. These samples, 8351-44, Arumbera Sandstone LP-Єa 8351-45 and 8351-46a (see below), are from lithic sandstone units interbedded with conglomerates in the lower part of the Brewer Conglomerate Julie Formation LPuj in Ellery Creek (Fig. 1). In addition to the Ediacaran Tingate samples, one of us (JDG) collected a Fig. 2. Stratigraphic column with ages, indicating the conodont reworking. Conodonts from samples in the large limestone clast of cobble size (sample JG Brewer Conglomerate are reworked from Pacoota 2005-1) from a conglomerate bed within the Sandstone Sequence 2 and Sequence 3, while the Hermannsburg Sandstone also in Ellery Creek sample from the Hermannsburg Sandstone contains (Fig. 1). The samples collected and their location conodonts reworked from the lower part of the Horn are listed below. Valley Siltstone. Rock unit symbols are as used in Figure 1. Note that in the Ellery Creek section, from Brewer Conglomerate which this column is taken, the Stokes Siltstone is Tingate sample 8351-44; Grid Ref LP025622 absent, having been eroded prior to deposition of the Hermannsburg 1:250, 000 (1979). Mereenie Sandstone. Tingate sample 8351-45; Grid Ref LP023625 Hermannsburg 1:250, 000 (1979). of the Ninmaroo Formation in the Georgina Tingate sample 8351-46a; Grid Ref LP025629 Basin (Fig. 3). The latter sample was used to Hermannsburg 1:250, 000 (1979). obtain comparative material of Hirsutodontus simplex, which was previously unknown from Hermannsburg Sandstone the Amadeus Basin. Gorter sample JG 2005-1; 23°49’31.30”S, Some of the samples formed part of a Ph.D. 133°04’14.30”E Hermannsburg 1:250, 000. study of fission track ages in the Amadeus Basin and adjacent provinces by Tingate (1990), who Ninmaroo Formation, Jiggamore Member collected a number of samples from the Brewer BMA section of Ripperdan et al. (1992) (see Conglomerate which yielded reworked, poorly Shergold et al. 1991a). Black Mountain, 548 AAP Memoir 34 (2007)

North Amadeus Georgina Period, Epoch, Australian N. American Atlantic Basin Basin Stage graprolites Midcontinent conodonts conodonts stratigraphy stratigraphy 471.8 ± 1.6 Ch2 l.primulus

Ch1 D.protobifidus O.evae R.andinus Be4 Be3 P.fruticosus Horn Valley Floian Be2 Siltstone Be1 P.elegans O.communis T. La3 approximatus O.elongatus 478.6 ± 1.7 A.deltatus Coolibah Pacoota Formation Early P.gracilis sequence 4 Ordovician Tripodus D.deltatus- La2b A.pulchellus

P.proteus Kelly Creek Fm O.costatus D. aff.amoenus Tremadocian P.deltifer M.dianae La2a A.victoriae R.manitouensis Datson Pacoota Member P.jacksoni C.angulatus C.angulatus La1b sequence 3 La1a Anisograptus Corrie Member Pre-La1 l.fluctivagus l.fluctivagus 488.3 ± 1.7 Mort Mbr Cordylodus Pacoota intermedius spp. Jiggamore sequence 2 Member Stage 10 Cordylodus

proavus Ninmaroo Formation Furongian Cambrian Unbunmaroo Pacoota Eoconodontus Member sequence 1

Fig. 3. Correlation of Furongian and Early Ordovician stratigraphic units from the Amadeus and Georgina basins. These are calibrated against the global standard scale of stages, the Australia graptolite succession and the North Atlantic and Midcontinent conodont biostratigraphic schemes.

Georgina Basin, western Queensland. Sample All illustrated specimens have been lodged in BMA 102 is approximately at the 662 m level the Commonwealth Palaeontological Collection in the section. 22° 31.65’S, 140° 16.80’E. (CPC) at Geoscience Australia, Canberra. All of the faunal elements discussed here have Pacoota Sandstone, Sequence 3 a conodont colour alteration index (CAI) of 1, the 87-2047/S-T, 24 m above the base of sequence 3; same as in situ conodonts from the Horn Valley approximately at ‘seq 3’ locality in Fig. 1; 23° Siltstone and Pacoota Sandstone. This suggests 48.83’S, E 133° 03.88’E. that the source sediments, either first or second 88-2052/55, 82.5 m above base of sequence 3; cycle, were never buried to depths of greater than approximately at ‘seq 3’ locality in Fig. 1; 23° about 1200 to 1500 m (Epstein et al. 1977). 48.92’S, 133° 03.84’E. Tingate Sample 8351-44 CONODONT FAUNAS This sample yielded only two elongate, rounded, All of the Brewer Conglomerate and coniform elements, neither of which could be Hermannsburg Sandstone samples listed above identified even to genus level (see Table 1). The have yielded reworked conodonts (see Table 1). general nature of these two conodont elements AAP Memoir 34 (2007) 549

Fig. 4. Hirsutodontus simplex. Scale bar = 100 microns, except for K-L where it = 40 microns. A-E, K-L, reworked left coniform element, CPC 39653 (Tingate 8351-45); A, oblique oral-outer lateral view showing broken cusp base; B, outer lateral view; C, oblique oral-inner lateral view with broken cusp base; D, outer lateral view; E, oblique posterior-outer lateral view; K, enlargement of A showing eroded spine bases; L, enlargement of E showing eroded spine bases; F-H, comparative specimen from the Jiggamore Member of the Ninmaroo Formation right coniform element, CPC 39654 (BMA 102); F, outer lateral view; G, inner lateral view; H, anterior view; I-J, right coniform element, CPC 39655 (BMA 102); I, anterior view; J, inner lateral view. 550 AAP Memoir 34 (2007)

Fig. 5. Reworked conodonts from the Brewer Conglomerate (A-K, P) and comparative Pacoota Sandstone conodonts (L-O, Q-R). Scale bar = 100 microns, except for P-R where it = 200 microns. A-B, Q-R, Drepanodus sp.; A-B, right element CPC 39656 (Tingate 8351-45); A, inner lateral view; B, enlargement of eroded cusp region; Q, left S element, CPC 39665 (RSN 88-2052/55), inner lateral view; R, left S element, CPC 39666 (RSN 87-2047/T), inner lateral view. C-D, Scolopodus sp., right element, (continued opposite) AAP Memoir 34 (2007) 551 suggests that they were probably derived from (Shergold et al. 1991b), an interval not zoned by rocks equivalent in age to Sequence 3 of the trilobites, but corresponding to the Iapetognathus Pacoota Sandstone. to Rossodus manitouensis Zones of Miller et al. (2003). This interpretation suggests that Sequence Tingate Sample 8351-45 2 of the Pacoota Sandstone is equivalent to the This sample yielded a poorly preserved conodont Jiggamore Member of the Ninmaroo Formation fauna with many of its 61 elements broken. Most and corresponds to the Hirsutodontus simplex show some degree of post-mortem abrasion and Zone and possibly the Cordylodus lindstromi rounding, suggesting that the conodont elements Zone. In Utah, H. simplex occurs in the lower had been weathered free from their initial part of the Barn Canyon Member of the House depositional matrix and transported some distance Limestone where it is confined to theCordylodus prior to their incorporation in the Devonian intermedius Zone (Miller et al. 2003). lithic sandstone of the Brewer Conglomerate. Aloxoconus iowaensis is an Early Ordovician Identification of elements is difficult and of conodont that is known to occur in Sequence the 61 obtained, only 12 can be identified to 3 of the Pacoota Sandstone. Specimens of A. generic level and only two to species level. Taxa iowaensis have been collected from this interval identified (see Table 1) include Hirsutodontus in the Ellery Creek section. In Utah, A. iowaensis simplex (Druce & Jones, 1971) (Fig. 4A-E, is known to range from the middle part of the Barn K-L), Aloxoconus iowaensis (Furnish, 1938) Canyon Member of the House Limestone into the (Fig. 5J-O), Drepanodus sp. (Fig. 5A-B, Q-R), Fillmore Formation; i.e., from the Iapetognathus Drepanodus? sp. (Fig. 5E, H-I, P), Scolopodus Zone to the Rossodus manitouensis Zone (Miller sp. (Fig. 5C-D) and Ulrichodina sp. (Fig. 5F-G). et al. 2003). All of the fauna is represented by coniform elements; no ramiform elements were obtained. Tingate Sample 8351-46a The two specimens identified to species level (H. This sample yielded sixteen elements, only two simplex and A. iowaensis) are derived from strata of which were tentatively identified to genus level equivalent in age to the Pacoota Sandstone. (i.e., Drepanodus? sp. and Scolopodus? sp.). The Hirsutodontus simplex is a latest Cambrian general nature of this fauna suggests that they (Furongian) conodont that has not previously were probably derived from rocks equivalent in been found in the Amadeus Basin. However, age to Sequence 3 of the Pacoota Sandstone. in the Georgina Basin in western Queensland, it has been found in the Jiggamore Member of Sample JG 2005-1 the Ninmaroo Formation (Druce & Jones 1971; This sample yielded a conodont fauna comprising Shergold et al. 1991a) (Fig. 3). Shergold et al. more than 900 elements (Table 1) which, in (1991b) summarised the lithostratigraphy and addition to unidentified coniform elements, biostratigraphy of the Pacoota Sandstone and contained 53 specimens of one species identified observed that no body fossils were recovered from as Oepikodus cleftus Nicoll & Ethington, 2003 Sequence 2, the unit consisting of bioturbated (Fig. 6B-C), a form known only from the lower sandstone with Skolithos and Rusophycus part of the Early Ordovician Horn Valley Siltstone representing storm and tidal shelf sands. The in the Amadeus Basin (Nicoll & Ethington 2003). age of Sequence 2 was constrained only by The fauna also contains O. communis (Ethington the ages of the underlying Sequence 1 and the & Clark, 1964) (Fig. 6A), Jumudontus gananda overlying Sequence 3. Sequence 1 (Assemblage Cooper, 1981 (Fig. 6D), Bergstroemognathus kirki 1) is correlated (Fig. 3) to the Neoagnostus Stait & Druce, 1993 (Fig. 6H), Cooperignathus quasibilobus-Shergoldia nomas to Mictosaukia nyinti (Cooper, 1981) (Fig. 6E-F), Cornuodus perplexa Assemblage Zones of the late Payntonian longibasis (Lindström, 1955) (Fig. 6G) and to early Datsonian of western Queensland numerous unidentified coniform taxa commonly (Shergold et al. 1991b; Nicoll & Shergold recovered from the Horn Valley Siltstone (Cooper 1991). The overlying Sequence 3 (Assemblage 1981). The fauna is well preserved, unlike that 2) is correlated with the upper part (Corrie to from the Brewer Conglomerate lithic sandstone Datson Members) of the Ninmaroo Formation samples. The CAI value of the conodont elements CPC 39657 (Tingate 8351-45); C, inner lateral view, D, oral view. E, H-I, P, Drepanodus? sp. E, right element, CPC 39658 (Tingate 8351-45); inner lateral view; H-I, right element, CPC 39660 (Tingate 8351-45); H, inner lateral view; I, oral view; P, element fragment CPC 39664 (Tingate 8351-45), lateral view; F-G, Ulrichodina sp., Sa element, CPC 39659 (Tingate 8351-45); F, anterior view; G, oral view. J-O, Aloxoconus iowaensis; J-K, Sa element, CPC 39661 (Tingate 8351-45); J, posterior view; K, oral view; L-M, Sa element CPC 39662 (RSN 87-2047/S); L, posterior view; M, oblique right lateral view; N-O, Sa element, CPC 39663 (RSN 87-2047/S); N, posterior view; Q, oral view. 552 AAP Memoir 34 (2007)

Fig. 6. Reworked Horn Valley Siltstone conodonts from the Hermannsburg Sandstone (Locality JG 2005-). Scale bar = 200 microns, except for H where it is 500 microns; A, Oepikodus communis, left Pb element, inner lateral view, CPC 39667. B-C, Oepikodus cleftus; B, left Pb element, inner lateral view, CPC 39668; C, Sa element, lateral view, CPC 39669. D, Jumudontus gananda, left Pb element, inner lateral view, CPC 39670. E-F, Cooperignathus nyinti, left Pa element, CPC 39671; D, oral view; E, inner lateral view. G, Cornuodus longibasis, Sa element, lateral view, CPC 39672. H, Bergstroemognathus kirki, Sa element, posterior view, CPC 39673. AAP Memoir 34 (2007) 553 of the sample is CAI 1, a value similar to that (Geological Survey of WA) for their critical found in samples from the nearby Horn Valley reviews and helpful suggestions. Siltstone. REFERENCES DISCUSSION Co o p e r , B.J., 1981. Early Ordovician conodonts The recovery of Late Cambrian and Early from the Horn Valley Siltstone, Central Australia. Ordovician conodonts in the lower part of the Palaeontology 24, 147-183. Brewer Conglomerate supports the observation Dr u c e , E.C. & Jo n e s , P.J., 1971. Cambro-Ordovician of Jones (1972, 1991) that reworked Cambrian conodonts from the Burke River Structural Belt, and Ordovician sediments are a component of the Queensland. Bureau of Mineral Resources, Geology lower part of the Brewer Conglomerate. and Geophysics, Bulletin 110, 117 p. The reworked fauna appears to have been Ep s t e i n , A.G., Ep s t e i n , J.B. & Ha r r i s , L.B., 1977. derived from three sources, two from within Conodont color alteration – an index to organic the time range of Pacoota Sandstone deposition metamorphism. U.S. Geological Survey Professional and a third from the overlying Horn Valley Paper 995, 1-27. Siltstone. The recovery of a single element of Et h i n g t o n , R.L. & Cla r k , D.L., 1964. Conodonts from the Late Cambrian conodont Hirsutodontus the El Paso Formation (Ordovician) of Texas and simplex from the Brewer Conglomerate in the Arizona. Journal of Paleontology 38, 685-704. Amadeus Basin provides a new window on the Fu r n i s h , W.M., 1938. Conodonts from the Prairie depositional and erosional history of the basin. du Chien (Lower Ordovician) beds of the upper This reworked Hirsutodontus simplex element Mississippi valley. Journal of Paleontology 12, from sample 8351-45 thus must be from a unit 318-340. that is stratigraphically equivalent to Pacoota Jo n e s , B.G., 1972. Upper Devonian to Lower Sandstone Sequence 2, but it is from a depositional stratigraphy of the Pertnjara Group, environment of more open marine aspect than the Amadeus Basin, central Australia. Journal of the outcropping ichnofauna-dominated sediments at Geological Society of Australia 19, 229-249. 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Conodonts from the lower- Sandstone containing A. iowaensis is presently most Ordovician strata of south-central Sweden. located about 3 km north of the sample site (Fig. Geologiska Föreningens i Stockholm Förhandlingar, 1). However, the degree of weathering reflected 76, 517-604. in the reduction of the source sediment to discrete Mi ll e r , J.F., Ev a n s , K.R., Lo ch , J.D., Et h i n g t o n , mineral grains and the rounding and abrasion of R.L., St i t t , J.H., Ho lm e r , L. & Po p o v , L.E., 2003. the conodont elements suggests a greater distance Stratigraphy of the Sauk III Interval (Cambrian- of transportation from source to burial. Ordovician) in the Ibex Area, Western Millard This study suggests that during the Late County, Utah and Central Texas. Brigham Young Cambrian, the deepest part of the Amadeus University Geology Studies 47, 23-118. Basin lay north of the present basin margin in the Ni c o ll , R.S. & Et h i n g t o n , R.L., 2003. Lissoepikodus McDonnell Ranges. It supports the suggestion nudus gen. et sp. nov. and Oepikodus cleftus sp. by Shaw (1991) that the presently isolated nov., new septimembrate conodont taxa from the Ordovician sediments of the Ngalia Basin Early Ordovician of Australia and Nevada. Courier represented the former depositional margin of Forschungsinstitut Senckenberg 245, 427-461. the Amadeus Basin. Ni c o ll , R.S. & Sh e r g o ld , J.H., 1991. Revised Late Cambrian (pre-Payntonian - Datsonian) conodont ACKNOWLEDGEMENTS biostratigraphy at Black Mountain, Georgina Basin, We wish to thank Peter Tingate (University of western Queensland, Australia. BMR Journal of Adelaide) for providing most of the samples on Australian Geology & Geophysics 12, 93-118. which this study is based. We thank Ian Percival Pla y f o r d , G., Jo n e s , B.G. & Ke m p , E.M., 1976. (Geological Survey of NSW) and Peter Haines Palynological evidence for the age of the synorogenic 554 AAP Memoir 34 (2007)

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