Interpretation of aeromagnetic and gravity data from western New South Wales – identifying basin and basement geology

Abstract

SUMMARY High resolution aeromagnetic data and regional gravity data have been interpreted by the Geological Survey of New South Wales for the western half of the state. The region lies between the Curnamona Province and Koonenberry Belt in the far west, and the Lachlan Orogen in the central west, and it extends from the Queensland border to the Victorian border. Overlapping sedimentary basins – the Darling Basin, Eromanga Basin, and Murray Basin – cover virtually all the basement rocks throughout the region. The primary objective is to identify lithological and structural variations within the basement layer, using them as the basis for creating an interpretive geophysical–geological map of the basement surface. Samples and information from drill holes (including water bores) provided limited geological control on the basement layer. Major results are improved classification of the numerous interpreted granite intrusions and recognition of major structures. Regions have been identified where basement occurs at depths viable for mineral exploration. The detailed study has also defined subtle features in the aeromagnetic data that relate to basin structure and stratigraphy. These sequences include the Cobar Supergroup and the Darling Basin, and provide information which could be applicable to petroleum exploration, and groundwater and geosequestration investigations.