|Adelaide Geosyncline; Adelaide Rift Complex|
|State(s)||South Australia; New South Wales; Victoria|
|Basin type||Rift; Passive margin|
|Orogeny||Delamerian; Alice Springs; Spriggs|
|Faults||Paralana; Norwest; Anabama-Redan|
The Adelaide Superbasin (previously known as the Adelaide Geosyncline and Adelaide Rift Complex) is a major Neoproterozoic to middle Cambrian geological province in central and south-east South Australia, western New South Wales, and western Victoria.
The Adelaide Superbasin consists of a thick pile of sedimentary rocks and minor volcanic rocks that were deposited on the eastern margin of Australia during the time of breakup of the supercontinent Rodinia. A number of authors have noted the similarity in these sedimentary rocks with rocks found in western North America and have suggested that they were formerly adjacent to each other in Rodinia. This is one major correlation in the SWEAT (south-west USA against East Antarctica) reconstruction of Rodinia.
Particularly notable events that are preserved in the rock record of the Adelaide Superbasin are the two Neoproterozoic Snowball Earth events (the Sturtian and Marinoan Glaciations), the Neoproterozoic Oxygenation Event, the Ediacaran Acraman bollide ejecta layer and the rise of Ediacaran Fauna.
North–south it stretches over 850 km (530 mi) from the Peake and Denison Ranges in the central-north of South Australia down through the Flinders Ranges and Mount Lofty Ranges, narrowing at the Fleurieu Peninsula and extending onto Kangaroo Island. West–east it stretches about 700 km (430 mi) from the eastern margin of Lake Gairdner across to the Barrier Ranges of New South Wales. The true northern and eastern extent of the Adelaide Superbasin is not well known due to much of the basin being buried beneath younger basins, including the Murray Basin, and is the subject of current research.
It is thought that the Moyston Fault in Victoria marks the eastern boundary and the northern extension may continue underneath and potentially include the Warburton Basin; however, this remains speculative. Most of the outcropping rock today is within the two major mountain ranges of South Australia: the Flinders Ranges and the Mount Lofty Ranges.
Much like the partly coeval Centralian Superbasin it contains several named basins and sub-basins. The oldest and largest of these is the Adelaide Rift Complex, with the adjoining and relatively undeformed Stuart Shelf, Torrens Hinge Zone and Coombalarnie Platform making up the remaining Neoproterozoic provinces. The Stansbury Basin (including its sub-province the Kanmantoo Province/Trough) and Arrowie Basin (including its sub-province the Yalkalpo Sub-basin) are the two known Cambrian provinces within the Adelaide Superbasin.
Deposition in the Adelaide Superbasin began just prior to 830 Ma as Laurentia (and possibly an intervening continent, see Rodinia for alternative reconstructions) began to rift away from Australia during the breakup of the supercontinent Rodinia. Deposition continued through to the Delamerian Orogeny c. 514–490 Ma at which time deposition in the Adelaide Superbasin stopped and the rocks were folded and deformed. Initially, deposition occurred from gradual subsidence of peneplained cratonic lithosphere before developing into a rift basin.
After about 725 Ma, deposition continued in a mostly passive margin setting along the western edge of the Palaeo-Pacific Ocean, with renewed rifting during the Ediacaran to the east (present day) of the main depocentres until being terminated by the Delamerian Orogeny. The most abundant rock types indicate a transition from evaporitic depositional environments through to proximal marine, glacial and marine depositional environments. The thickest parts of the stratigraphy reach a total cumulative thickness of about 24,000 m.
Adelaide Rift Complex
The Adelaide Rift Complex is the oldest and most central part of the Adelaide Superbasin. It is a series of rift troughs and passive margins basins with protracted development from c. 840 Ma to c. 550 Ma with the top of the sedimentary sequence marked by a major basin-wide disconformity separating it from the Cambrian Arrowie and Stansbury Basins.
Torrens Hinge Zone
The Torrens Hinge Zone is a transitional area between the relatively undeformed platform deposits of the Stuart Shelf and the deformed rocks of the central Adelaide Rift Complex. It runs along the western margin of the primary rift basin.
The Stuart Shelf is a region of platform deposits on the western rift shoulder that overlies the Gawler Craton. It experienced deposition in the late Neoproterozoic after the Sturtian Glaciation during a period of marine transgression and remains relatively undeformed to this day.
The Coombalarnie Platform, like the Stuart Shelf, is a region of platform deposits; however, it overlies the Curnamona Province to the north-east of the main depocentre. Deposition occurred only after a major marine transgression event during the late Neoproterozoic after the Sturtian Glaciation.
The Stansbury Basin is one of the two known Cambrian basins of the Adelaide Superbasin. It is exposed in the south of the superbasin, extending from Kangaroo Island and the Mount Lofty Ranges toward Victoria underneath the Murray Basin. The true eastward extent of this basin is not well understood and is a focus of current geological research in South Australia. It is likely that deposition was continuous with the Arrowie Basin to the north.
The Kanmantoo Province (also Kanmantoo Trough) is a deeply subsisdent rift formed in early Cambrian. It forms the eastern and southern portion of the Stansbury Basin, extending to the Glenelg River region of Victoria. Most rocks were highly deformed and experienced moderate to high grade metamorphism during the Delamerian Orogeny.
The Arrowie Basin is second of the two known Cambrian basins of the Adelaide Superbasin. It extends from the Stuart Shelf in the west across the Flinders Ranges to western New South Wales where it forms part of the Neoproterozoic–Cambrian cover on the Curnamona Province.
|Geochronology||South Australia||New South Wales|
|Eon||Era||Period||Local Chronostratigraphy (historical – not in use)||Supergroup||Groups||Subgroups||Groups||Subgroups|
|Phanerozoic||Palaeozoic||Cambrian||Unconformity overlaid by Permian glacial sediments|
|Mid-late||Moralana Supergroup||Lake Frome Group / Kanmantoo Group / Yorke Group|
|Early||Kanmantoo Group / Yorke Group / Kangaroo Island Group||Keynes Subgroup / Bollaparudda Subgroup|
|Normanville Group / Hawker Group / Pavy Group / Kangaroo Island Group|
|Proterozoic||Neoproterozoic||Ediacaran||Marinoan||Heysen Supergroup||Wilpena Group||Pound Subgroup||Farnell Group|
|Depot Springs Subgroup|
|Cryogenian||Umberatana Group||Yerelina Subgroup||Toorrowangee Group||Teamsters Creek Subgroup|
|Yudnamutana Subgroup||Yancowinna Subgroup|
|Tonian||Warrina Supergoup||Burra Group||Belair Subgroup||Unconformity|
|Willouran||Callanna Group||Curdimurka Subgroup||Poolamacca Group||Wendalpa Subgroup|
|Arkaroola Subgroup||Pintapah Subgroup|
|Mesoproterozoic||Unconformity underlain by metamorphosed Mesoproterozoic basement (Gawler Craton, Curnamona Province)|
Sedimentation in the Adelaide Superbasin ended in the middle Cambrian, when tectonic inversion occurred along the eastern margin of Neoproterozoic and Cambrian cratonic Australia and the margin became a subduction zone of the Palaeo-Pacific. After this time the region experienced an orogeny (mountain-building period) extending into the Ordovician. Foden et al. (2006) suggest that this orogeny lasted from ~514 Ma to 490 Ma. This event is called the Delamerian Orogeny, named after Delamere, a small town on the Fleurieu Peninsula where evidence was found for the event. The orogeny caused substantial folding, buckling, and faulting of the strata, and resulted in the creation of a major mountain range, the eroded stumps of which can today be seen as the Mount Lofty and Flinders Ranges. Not all of the basin experienced tectonic activity; the deposits on the Stuart Shelf and Coombalarnie Platform to the north-west and north-east remained undisturbed (and still do today).
Fossils of the earliest Animalia are found in the Adelaide Superbasin. The first of these might be the probable sponges found in the Trezona Formation, although the first confirmed Animalia are the world-renowned Ediacaran fauna, named for the Ediacara Hills where they were first discovered in South Australia in 1946. They occur at the end of the Neoproterozoic, and in 2004 the location gave its name to the last geological period of the era, the Ediacaran.
Recent geological history
The ranges formed during the Delamerian orogeny continue to erode, and intra-plate subsidence is occurring. In the South Mount Lofty Ranges this has resulted in rifting and the formation of graben structures, creating the long parallel faults which shape the Adelaide Plains.
- Lloyd, Jarred C.; Blades, Morgan L.; Counts, John W.; Collins, Alan S.; Amos, Kathryn J.; Wade, Benjamin P.; Hall, James W.; Hore, Stephen; Ball, Ashleigh L.; Shahin, Sameh; Drabsch, Matthew (8 July 2020). "Neoproterozoic Geochronology and Provenance of the Adelaide Superbasin". Precambrian Research: 105849. doi:10.1016/j.precamres.2020.105849. ISSN 0301-9268.
- Mawson, Douglas; Sprigg, Reginald (1950). "Subdivision of the Adelaide System". Australian Journal of Science. 13 (3): 69–72.
- Preiss, Wolfgang V., ed. (1987). The Adelaide Geosyncline : late Proterozoic stratigraphy, sedimentation, palaeontology, and tectonics. Bulletin 54. Geological Survey of South Australia. Adelaide: Dept. of Mines and Energy. ISBN 0-7243-7845-6. OCLC 27539001.
- Preiss, Wolfgang V. (2000). "The Adelaide Geosyncline of South Australia and its significance in Neoproterozoic continental reconstruction". Precambrian Research. 100 (1–3): 21–63. Bibcode:2000PreR..100...21P. doi:10.1016/S0301-9268(99)00068-6.
- Veevers, J. J.; Walter, M. R.; Scheibner, E. (1997). "Neoproterozoic Tectonics of Australia‐Antarctica and Laurentia and the 560 Ma Birth of the Pacific Ocean Reflect the 400 M.Y. Pangean Supercycle". The Journal of Geology. 105 (2): 225–242. Bibcode:1997JG....105..225V. doi:10.1086/515914. ISSN 0022-1376.
- Powell, C.McA.; Preiss, Wolfgang V.; Gatehouse, Colin G.; Krapez, B.; Li, Zheng-Xiang (1994). "South Australian record of a Rodinian epicontinental basin and its mid-neoproterozoic breakup (∼700 Ma) to form the Palaeo-Pacific Ocean". Tectonophysics. 237 (3–4): 113–140. doi:10.1016/0040-1951(94)90250-X.
- Moores, E. M. (1991). "Southwest U.S.-East Antarctic (SWEAT) connection: A hypothesis". Geology. 19 (5): 425. Bibcode:1991Geo....19..425M. doi:10.1130/0091-7613(1991)019<0425:SUSEAS>2.3.CO;2.
- Dalziel, Ian W.D. (1991). "Pacific margins of Laurentia and East Antarctica-Australia as a conjugate rift pair: Evidence and implications for an Eocambrian supercontinent". Geology. 19 (6): 598. Bibcode:1991Geo....19..598D. doi:10.1130/0091-7613(1991)019<0598:PMOLAE>2.3.CO;2.
- Och, Lawrence M.; Shields-Zhou, Graham A. (2012). "The Neoproterozoic oxygenation event: Environmental perturbations and biogeochemical cycling". Earth-Science Reviews. 110 (1–4): 26–57. Bibcode:2012ESRv..110...26O. doi:10.1016/j.earscirev.2011.09.004.
- GOSTIN, V. A.; HAINES, P. W.; JENKINS, R. J. F.; COMPSTON, W.; WILLIAMS, I. S. (11 July 1986). "Impact Ejecta Horizon Within Late Precambrian Shales, Adelaide Geosyncline, South Australia". Science. 233 (4760): 198–200. Bibcode:1986Sci...233..198G. doi:10.1126/science.233.4760.198. ISSN 0036-8075. PMID 17737290. S2CID 11307364.
- Sprigg, Reginald C. (1948). "Jellyfish from the Basal Cambrian in South Australia". Nature. 161 (4093): 568–569. Bibcode:1948Natur.161..568S. doi:10.1038/161568a0. ISSN 0028-0836. S2CID 4098098.
- Droser, Mary L.; Gehling, James G. (21 April 2015). "The advent of animals: The view from the Ediacaran". Proceedings of the National Academy of Sciences. 112 (16): 4865–4870. Bibcode:2015PNAS..112.4865D. doi:10.1073/pnas.1403669112. ISSN 0027-8424. PMC 4413262. PMID 25901306.
- Counts, John W. (2017). The Adelaide Rift Complex in the Flinders Ranges: geologic history, past investigations and relevant analogues. Report Book, no. 2017/00016. Geological Survey of South Australia. Department of Premier and Cabinet. Adelaide, South Australia.https://sarigbasis.pir.sa.gov.au/WebtopEw/ws/samref/sarig1/wcir/Record?r=0&m=1&w=catno=2039731
- Preiss, Wolfgang V.; Alexander, Elinor M.; Cowley, Wayne M.; Schwarz, Michael P. (2002). "Towards defining South Australia's geological provinces and sedimentary basins". MESA. 27: 39–52.
- Foden, John; Elburg, Marlina A; Dougherty-Page, Jon; Burtt, Andrew (2006). "The Timing and Duration of the Delamerian Orogeny: Correlation with the Ross Orogen and Implications for Gondwana Assembly". The Journal of Geology. 114 (2): 189–210. Bibcode:2006JG....114..189F. doi:10.1086/499570. hdl:2440/23647. ISSN 0022-1376.
- Foden, John; Elburg, Marlina; Turner, Simon; Clark, Chris; Blades, Morgan L.; Cox, Grant; Collins, Alan S.; Wolff, Keryn; George, Christian (2020). "Cambro-Ordovician magmatism in the Delamerian orogeny: Implications for tectonic development of the southern Gondwanan margin". Gondwana Research. 81: 490–521. Bibcode:2020GondR..81..490F. doi:10.1016/j.gr.2019.12.006.
- Cawood, Peter A. (2005). "Terra Australis Orogen: Rodinia breakup and development of the Pacific and Iapetus margins of Gondwana during the Neoproterozoic and Paleozoic". Earth-Science Reviews. 69 (3–4): 249–279. Bibcode:2005ESRv...69..249C. doi:10.1016/j.earscirev.2004.09.001.
- Preiss, Wolfgang V.; Alexander, Elinor M.; Cowley, Wayne M.; Schwarz, Michael P. (2002). "Towards defining South Australia's geological provinces and sedimentary basins". MESA Journal. 27: 39–52.
- Belperio, Antonio P.; Preiss, Wolfgang V.; Fairclough, Martin C.; Gatehouse, Colin G.; Gum, Justin C.; Hough, J.; Burtt, Andrew (1998). "Tectonic and metallogenic framework of the Cambrian Stansbury Basin - Kanmantoo Trough, South Australia". ASGO Journal of Australian Geology and Geophysics. 17 (3): 183–200.
- Preiss, Wolfgang V. (1982). "Supergroup classification in the Adelaide Geosyncline". Transactions of the Royal Society of South Australia. 106: 81–83.
- Drexel, John F.; Preiss, Wolfgang V.; Parker, A.J., eds. (1993). The Geology of South Australia. Geological Survey of South Australia. Adelaide: Mines and Energy South Australia. ISBN 0-7308-4147-2. OCLC 30439436.
- Lloyd, Jarred (2020), Lithostratigraphic Correlation Chart of the Adelaide Superbasin (Neoproterozoic), doi:10.6084/m9.figshare.11812047, retrieved 16 July 2020
- Cooper, P.F.; Tuckwell, K.D.; Gilligan, L.B.; Meares, R.M.D. (1974). "Geology of the Torrowangee and Fowlers Gap 1:100,000 Sheets". Geological Survey of New South Wales, Department of Mines, Sydney, New South Wales.
- Preiss, Wolfgang V.; Cowley, Wayne M. (1999). "Genetic stratigraphy and revised lithostratigraphic classification of the Burra Group in the Adelaide Geosyncline". MESA. 14: 30–40.
- Maloof, Adam C.; Rose, Catherine V.; Beach, Robert; Samuels, Bradley M.; Calmet, Claire C.; Erwin, Douglas H.; Poirier, Gerald R.; Yao, Nan; Simons, Frederik J. (2010). "Possible animal-body fossils in pre-Marinoan limestones from South Australia". Nature Geoscience. 3 (9): 653–659. doi:10.1038/ngeo934. ISSN 1752-0894.
- Bobrovskiy, Ilya; Hope, Janet M.; Ivantsov, Andrey; Nettersheim, Benjamin J.; Hallmann, Christian; Brocks, Jochen J. (21 September 2018). "Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals". Science. 361 (6408): 1246–1249. doi:10.1126/science.aat7228. ISSN 0036-8075. PMID 30237355. S2CID 52306108.
- Sprigg, Reg. C. (1948). "Jellyfish from the Basal Cambrian in South Australia". Nature. 161 (4093): 568–569. doi:10.1038/161568a0. ISSN 0028-0836. S2CID 4098098.
- Knoll, Andrew; Walter, Malcolm; Narbonne, Guy; Christie-Blick, Nicholas (1 March 2006). "The Ediacaran Period: a new addition to the geologic time scale". Lethaia. 39 (1): 13–30. doi:10.1080/00241160500409223. ISSN 0024-1164.
- Ludbrook, N.H. (1980). A guide to the geology and mineral resources of South Australia. Department of Mines and Energy. DJ Woolman Government Printer. Geological Survey of South Australia.