DEEP TECTONIC FOUNDATIONS OF THE EROMANGA BASIN

Abstract

The Eromanga Basin in eastern Australia is underpinned by major regional tectonic features which extend into it from adjacent basins and from the surrounding frame of older bedrock and basement. Their recognition and resolution require the integration of special treatments of gravimetric, magnetic and strato-structural data.

The features are major pattern discontinuities, generally strongly linear, and are part of a continental pattern. They are extensions of the same systems of major transcontinental tectonic trends which pass through and under surrounding orogenic centres, such as the Adelaide, Mount Isa, New England and Lachlan Geosynclines, the Arunta and Musgrave Blocks and the Georgetown Province. They are regional loci variously of intensified folding, faulting and fracture, and of anomalous heat flow gradients.

Their association with different ages of metallogenesis, and their repeated correspondence to lithologic and stratigraphic patterns, indicate that they are primary crustal features which have been tectonically active through most of geologic history, controlling gross basin morphology as well as more detailed distributions of particular sedimentary facies.

Their conjunctions show a spatial relationship to known petroleum deposits, suggesting that they fulfil a dynamic and thermal role in petroleum generation and accumulation. They provide an essential frame of reference for the recognition and development of more finely-tuned structural patterns which act as pathfinders in petroleum exploration.