Huynh, T., Betts, P. G. and Ailleres, L. 2001. Three-dimensional Modelling of Lithospheric-scale Structures of South Australia. In: Jessell, M. J. 2001. General Contributions: 2001. Journal of the Virtual Explorer.
Three-dimensional Modelling of Lithospheric-scale Structures of South Australia.

T. Huynh , P. G. Betts and L. Ailleres

Australian Crustal Research Centre, School of Geosciences, P.O. Box 28E
Monash University, Victoria 3800, Australia

Abstract Two- and three-dimensional forward modelling of gravimetric field data across South Australia has provided greater insight into the crustal architecture of the Archaean-Proterozoic Gawler Craton and its immediate surrounds. Profile modelling of the shallow crustal-level structures demonstrates that geometrical sources associated with the high frequency domain do not in general extend to depths greater than approximately 10km. A number of relatively high gravimetric anomalies which correspond to identifiable accretionary complexes show fundamental differences in the geometry, size and crustal levels from which the signatures are interpreted to be sourced. Profile modelling of the deeper crustal-level structures predominantly reflects the signature of the Archaean craton and the superposition of the shorter wavelength components of shallow-level sources. This modelling suggests fundamental differences in the response of the crustal architecture between the Gawler Craton and accreted margins of Palaeo- to Meso-proterozoic complexes. These two-dimensional interpretations were subsequently integrated into two different three-dimensional models, thereby providing a framework for property modelling in generating a synthetic gravimetric anomaly response for comparison with the measured data. The modelled gravimetric anomaly response of the shallow level structures demonstrates a poor level of correlation with the surveyed results, indicating strong disparities with geometry and rock density values. This suggests inadequate definition of the source geometries and rock properties, although well constrained in two-dimensions, in the three-dimensional modelling. The modelled gravimetric anomaly response of the deeper level structures demonstrates a moderate level of correlation with a match-filtered image of the gravimetric dataset, showing similar signatures of structures at an approximate depth of 16 km.



Geological Background

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Integrated Geological and Geophysical Modelling