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Methodology and Standards
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Updated:
17 May 2007
A transect through Central AustraliaObjectives of the transectThe transect was undertaken to resolve the source of major, long lived gravity anomalies in the continental interior. The central Australian region contains some of the largest gravity anomalies in continental interiors, with a series of elongate E-W highs and lows with a range of approximately 1200 µms-2 (Figure 1). Some of the earliest studies (eg., Forman & Shaw, 1973) observed that, although the gravity highs and lows correspond loosely with Proterozoic basement rocks and Neoproterozoic to Palaeozoic sedimentary basins respectively, the transitions from highs to lows are displaced towards the basement regions, suggesting that either the basement regions overthrust the northern margins of the basins, or that the crust under regions of basement must have more low density rocks than the regions under the basins. The region of anomalous gravity lies mostly within and adjacent to the Central Australian Megaelement, which is sandwiched between the North Australian and South Australian Megaelements (Figure 1 above, and Meyers et. al., 1996). Each megaelement is a broad region of continent that amalgamated from smaller fragments during continental growth and then subsequently acted and reacted as a single structural entity. A brief summary of the tectonic history of the region and references to earlier work are given by Korsch et. al. (1998). The tectonic history of the region suggests that the structures responsible for the gravity anomalies are Palaeozoic in age, and that the gravity anomalies have endured for hundreds of millions of years. Early attempts to model the regional gravity field (see summary in Wright et. al., 1991) did not pay full attention to isostatic considerations. Lambeck (1983) offered the hypothesis that the anomalies were caused by buckling and breaking of the crust under north-south compression. He suggested a tectonic model with a crustal structure broadly consistent with the observed gravity field. Acknowledgments
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