Late Precambrian to early Cambrian stratigraphy of the SW Georgina Basin, Australia

Abstract

The area to the N and NE of the Amadeus Basin in central Australia is currently being studied by the Bureau of Mineral Resources as part of a detailed investigation of the Georgina Basin. This has led to the recognition of numerous rock units within a previously undifferentiated latest Precambrian to early Cambrian sequence, and preliminary correlations with the Amadeus Basin are possible. The sequence starts with the lower of the 2 late Precambrian tillites, and includes stromatolitic carbonates and ichnofossiliferous sandstones. These outcrop on the Hay River, Tobermory and Huckitta 1:250000 sheet areas. No early Cambrian carbonates are yet known from the eastern region, but occur on Huckitta in the Mount Baldwin Formation and in the Amadeus Basin in the Todd River Dolomite. These contain early Cambrian shelly fossils. It is tentatively suggested that the late Precambrian–early Cambrian sediments of the SW Georgina Basin are the platform equivalents of the basinal sediments of the Amadeus Basin, with fully marine sediments of this age occurring in the Georgina Basin only in NW–SE trending grabens that cut across the platform.