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In the North Flinders Basin, which is the northern portion of the Adelaide “geosyncline,” late Proterozoic (Sturtian), glacigenic deposits lie unconformably on older Proterozoic sedimentary rocks of the Adelaidean succession or on crystalline basement. The glacigenic succession is highly variable in thickness and includes sections as much as 6,000 m thick. A four-fold regional stratigraphic subdivision (Units 1–4) contains two diamictite-laminated mudstone cycles. In the more distal, northern part of the basin, Unit 1 is mainly stratified diamictite, possibly formed by rain-out from floating ice while submarined) glacial erosion was taking place in more proximal settings. As the ice receded, a blanket of diamictons and associated glaciofluvial meltwater deposits was laid down in the south-central part of the basin. Locally, great thicknesses accumulated in paleovalleys. Unit 2 formed as a result of recession of the glacial ice. The dominant rock type is laminated mudstone, probably the result of deposition from widespread suspended sediment plumes distributed by meltwaters. Coarser material was introduced by traction and turbidity currents and as sporadic ice-rafted debris. Unit 3 is a widespread, thick, crudely stratified diamictite, produced largely by rain-out in a glacial marine setting, and is thought to represent a second ice advance to a tidewater position. Unit 4, like Unit 2, is mainly mudstones, with some coarser interbeds and dropstone-bearing horizons, reflecting glacial marine deposition during the final wasting of the Sturtian ice sheets. Overlying dark gray laminated shales of the Tapley Hill Formation formed in a post-glacial transgression. The Sturtian succession in this area is tentatively interpreted as having formed in a rift basin under a temperate climatic regime. It records two glacial advance-retreat cycles.

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