Characterisation of the Neoproterozoic succession of the northeastern Amadeus Basin, Northern Territory

Abstract

The Neoproterozoic to Palaeozoic Amadeus Basin is a large (~170 000 km2), elongate intracratonic basin in central Australia, located predominantly in the Northern Territory but extending into Western Australia. It preserves a depositional history spanning the Neoproterozoic to Devonian, which is punctuated by a number of epeirogenic, orogenic and erosional episodes that have resulted in unconformities and time breaks of local and/or regional extent. In addition, there is a recognised, but poorly documented, contribution of halotectonic activity during both depositional and tectonic periods of basin history. The focus of this study is the Neoproterozoic succession of the Amadeus Basin; this is best exposed along the structurally controlled northeast margin of the basin, which therefore was the location of the field investigations.

This Record addresses the lack of type sections and formal definitions for some units, and provides the first formal definitions for other units. The work has resulted in important revisions to the stratigraphy of the Neoproterozoic succession of the Amadeus Basin, including the promotion of the Bitter Springs Formation and its constituent Gillen, Loves Creek and Johnnys Creek members to group and formation status respectively, as well as the formalisation of the 'Finke beds' as the Wallara Formation. For each of the units in the Neoproterozoic succession, the following topics are addressed:

- diagnostic outcrop characteristics

- derivation of name and synonymy

- distribution of type and reference sections

- lithology and thickness

- bedding characteristics, sedimentary structures and fossils

- age, contacts and correlative units.

In addition, this Record includes numerous field images with detailed captions documenting the main characteristics of the units.