Research by Neville Alley and the GSSA’s Stephen Hore has culminated in the publication of Bulletin 57 Early Cretaceous sediments reveal a story of prolonged cold climate, glaciations, oscillating sea level and tectonic changes.

This publication is the most comprehensive treatment of Mesozoic sediments along the southern margin of the Eromanga Basin and Mount Painter uplands and their implications ever attempted. This research has been scrutinised and strongly endorsed by the geoscience community.

The Bulletin is divided into two volumes.

• Volume 1 brings the investigations together and draws conclusions at a local, regional and global scale.
• Volume 2 is a repository of data and an explanation of the methods used.

Text description of Bulletin 57 graphic (TXT, 1.0 KB)

Bulletin 57 outcomes

This bulletin makes a major revision to the stratigraphy of the southern Eromanga Basin and Mount Painter uplands, recognising two new stratigraphic units, and major and minor hiatuses in the succession.

Three new type sections, nine reference sections for key sedimentary units and three reference sections for key terrestrial tillite sections have been accurately established.

Bulletin 57 details the locations, within the Eromanga Basin and Mount Painter uplands, of physical evidence of three glacial events during the early Cretaceous and includes the petrology of selected samples. These are the first petrology samples to be documented anywhere in the world.

These glacial events have been correlated with the diverse global evidence for climatic changes during the Early Cretaceous and have thus attracted world-wide attention.

The stratigraphy of glacial sediments and interpreted paleoclimatic changes have been put in a geochronological context through extensive palynological and detrital zircon and monazite dating of sediments from boreholes and outcrop.

Using the distribution of glacial sediments and other potential glacial sediments elsewhere in Australia, as well as interpreted paleotopography during this time, the research reconstructs the extent of glacial ice over the Australian and Antarctic continents and ice-movement directions.

The Early Cretaceous paleoclimatic changes recognised in the southern Eromanga Basin and Mt Painter uplands makes a significant contribution to understanding future global climatic changes.

A detailed record of relative sea level changes for the Early Cretaceous has been constructed and correlated with the detailed global sea level curve.

Using sedimentological, lithological, palynological and detrital zircon and monazite evidence the study determines the source of sediments in the southern Eromanga Basin. This research has been able to reconstruct the nature of the land surface of the northern Flinders Ranges before deposition of the Eromanga Basin sediments, estimates the volume of bedrock and Mesozoic sediments stripped from the ranges since the Early Cretaceous and discusses tectonic changes within and marginal to the ranges since the Early Cretaceous.

The research findings have implications for mineral and energy resource exploration across eastern and southern South Australia, especially in the Eromanga, Bight and Otway basins.

In using geochemical exploration techniques, mineral explorers will be greatly aided in understanding the source of indicator minerals and geochemical signatures in areas affected by the Early Cretaceous glaciations and extensive areas marginal to the glaciers, including the Gawler and Curnamona cratons.

All the sites described and photographed have accurate GPS locations so that future researchers can locate key sites.

Download Volume 1

Download Volume 2

More information

Geochronological datasets and publications are available via SARIG.

Palynological and petrological thin sections are stored at the South Australia Drill Core Reference Library. Viewing can be arranged by contacting core Library staff.
+61 8 8379 9574
david.groom@sa.gov.au

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