Neoproterozoic to Earliest Cambrian Sequence Stratigraphy and Evolution of the Adelaide "Geosyncline", South Australia

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We propose to test and extend existing sequence stratigraphic and sedimentological interpretations of rocks of Neoproterozoic to earliest Cambrian age in the Adelaide geosyncline, South Australia. Sequence stratigraphy provides an independent method for significantly improving intro-basinal correlation in sparsely fossiliferous rocks, and a physical context in which to analyze biostratigraphic, chemostratigraphic, magnetostratigraphic and geochronological data. To the extent that the waxing and waning of Neoproterozoic ice sheets must have influenced sea level, we infer that at least some of the most persistent sequence boundaries are of global extent. This possibility needs to tested against the emerging stratigraphic record in key sections. The Adelaide geosyncline was selected as a reference section for sequence stratigraphic research on the basis of its great thickness (15 km), quality of outcrop, limited deformation and metamorphism, availability of seismic and core data in adjacent basins of the same age, varied biota (including acritarchs, trace fossils, Ediacara assemblage metazoa, and stromatolites), and amenability to stable isotope geochemistry. There is some potential also for U-Pb geochronology of ash beds, and we propose to search systematically for such layers. The proposed research will be co-ordinated with the work of others under the umbrella of Project 320 of the International Geological Correlation Programme (Neoproterozoic Events and Resources), with the long-term objective of documenting and evaluating the connections between a variety of biological, environmental and tectonic phenomena recorded in younger Neoproterozoic rocks.