RB 94/00028 South Australian record of a Rodinian epicontinental basin and its mid-Neoproterozoic breakup (+/-700 Ma) to form the Palaeo-Pacific Ocean.
Published: 01 Aug 1994 Created: 07 Nov 2024 Revised: 07 Nov 2024

The Neoproterozoic Adelaidean System and overlying Cambrian rocks are a thick succession of terrestrial and shallow marine sediments that were deposited on older continental crust near the eastern edge of the exposed Precambrian rocks in...

The Neoproterozoic Adelaidean System and overlying Cambrian rocks are a thick succession of terrestrial and shallow marine sediments that were deposited on older continental crust near the eastern edge of the exposed Precambrian rocks in Australia. The Adelaidean System records four major tectonic regimes: (1) early Neoproterozoic formation of an epicontinental, partly rifted basin;(2) mid-Neoproterozoic (~700 Ma) continental breakup and accumulation of a passive margin wedge;(3) latest Neoproterozoic/Early Cambrian renewed rifting, and (4) Middle to Late Cambrian conversion of the passive margin to a convergence zone during the development of the Delamerian Orogen. Deposition of the Adelaidean System commenced by ~830 Ma, when Australia was contiguous with Laurentia in the Rodinia supercontinent. Sandstone and evaporitic carbonate of an initial epicontinental basin are preserved as the lowest succession of the Adelaide Geosyncline and the Amadeus, Georgina, Ngalia, Officer and Savory Yeneena Basins. Mafic volcanics were extruded under NE-SW continental extension during the Willouran, which was overprinted by a more widespread east-west Torrensian extension. Continental breakup occurred around 700 Ma, during accumulation of the Sturtian glaciogenic deposits in rift valleys. The succeeding siltstone, sandstone, and carbonate were deposited on a passive continental margin that faced the newly formed Palaeo-Pacific Ocean as Laurentia rotated clockwise away from Australia. A wide Palaeo-Pacific Ocean existed at the time of the younger Ice Brook (Laurentian) and Marinoan (Australian) glaciations. Dextral shear between northern and southern Australia along the Paterson Petermann Ranges orogen in the 600 and 550 Ma interval, broke-up the continuity of the central Australian basins through uplift of the Musgrave Block, and led to renewed rifting, reflecting the latest Neoproterozoic continental breakup that formed the eastern margin of Laurentia. The South Australian passive margin persisted until the Middle Cambrian when convergence along the Pacific Ocean margin led to development of the Delamerian Orogen. Deposition of the marine siliciclastic Kanmantoo Group commenced in the late Early Cambrian in a rapidly subsiding trough, for which both extensional (rift-basin) and compressional (foredeep) origins have been proposed. Reversal of the eastwards-dipping Early Cambrian palaeoslope in the Middle Cambrian shed siliciclastic sediments back onto the continent from an initial uplift in advance of Delamerian deformation.

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Record No rb9400028
Topic Geoscientific Information
Type of Resource Document
Category Type
Document Type Departmental Publication - Geological Survey Geoscience Publication
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    Notes
    Notes: To be published in Tectonophysics.
    Geographic Locality: South Australia;Kimberley;Western Australia;Northern Territory;Pacific Ocean;Australia
    Doc No: RB 94/00028

    Notes: To be published in Tectonophysics. Geographic Locality: South Australia;Kimberley;Western Australia;Northern Territory;Pacific Ocean;Australia Doc No: RB 94/00028

    Language English
    Metadata Standard ISO 19115-3

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    Use constraints License
    License Creative Commons Attribution 4.0
    Persistent identifier https://pid.sarig.sa.gov.au/document/rb9400028
    Citation Powell, C.M.;Preiss, W.V.;Gatehouse, C.G.;Krapez, B.;Li, Z.X. 1994. RB 94/00028 South Australian record of a Rodinian epicontinental basin and its mid-Neoproterozoic breakup (+/-700 Ma) to form the Palaeo-Pacific Ocean. Departmental Publication - Geological Survey Geoscience Publication. Government of South Australia.
    https://pid.sarig.sa.gov.au/document/rb9400028

    Technical information

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    Geographic Reference GDA2020 (EPSG:7844)
    Geo bounding box {"type":"Polygon","coordinates":[[[129,-39],[141,-39],[141,-26],[129,-26],[129,-39]]]}
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