Neoproterozoic Geochronology and Provenance of the Adelaide Superbasin

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.precamres.2020.105849.

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Authors

Jarred Cain Lloyd , Morgan Blades, John W. Counts, Alan Collins , Kathryn J. Amos, Ben P. Wade, James W. Hall, Stephen Hore, Ashleigh L. Ball, Sameh Shahin

Abstract

The Adelaide Superbasin (Adelaide Rift Complex, Stuart Shelf, Torrens Hinge Zone, Coombalarnie Platform, and Cambrian Stansbury and Arrowie Basins) is a vast sedimentary basin in southern Australia that initiated due to the break-up of central Rodinia and, evolved into the Australian passive margin on edge of the Pacific Basin. Rocks within it contain evidence for the evolving earth system through the Neoproterozoic, including type sections of the Ediacaran fauna, Sturtian and Marinoan glaciations, and the GSSP for the base of the Ediacaran period. Much research over the last century has unravelled the lithostratigraphy and sedimentology of the basin. Despite this, the rocks are poorly dated, and their sedimentary provenance and link with tectonic geography is poorly known. This poor chronology hampers global and local efforts to gain a detailed understanding and chronological framework of the interplay between tectonics and momentous changes to the earth system during this time. This paper presents a comprehensive database of detrital zircon geochronology and review of geochronology for the Neoproterozoic of the Adelaide Superbasin, highlighting the stratigraphic, and spatial locations of available data.

In the north of the basin, zircons were sourced locally in the initial stages of rifting, ca. 830 Ma—from the adjacent Gawler Craton and Curnamona Province. During the late Tonian, detritus was transported along graben from the north-west, from the Musgrave Orogen, as the rift basin developed during the opening of the nascent Pacific Ocean. Cryogenian icesheets punctuate the detrital record with an ephemeral return to more localised rift shoulder sources. In the Ediacaran, there is an increasing influence of younger (<740 Ma) detrital zircon from an enigmatic source that we interpret to be from southern (i.e. Antarctic) sources, with a corresponding shift in the late Mesoproterozoic age peaks, from ca. 1180 Ma to ca. 1090 Ma, and corresponding decrease in older, ca. 1600 Ma, detritus. These changes in sediment source reflect the changing tectonic geography and large-scale environmental influence of the Cryogenian glaciations as the basin evolved from a local rift, to a larger rift basin and finally to a continental margin, with sedimentary input becoming increasingly restricted over time.

DOI

https://doi.org/10.31223/osf.io/3mjc2

Subjects

Earth Sciences, Geology, Physical Sciences and Mathematics

Keywords

Adelaide Rift Complex, Neoproterozoic, Adelaide Fold Belt, Adelaide Geosyncline, Adelaide Superbasin, detrital zircon

Dates

Published: 2020-07-15 14:52

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License

CC BY Attribution 4.0 International

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