1887
Volume 20, Issue 1-2
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

A prominent positive gravity anomaly overlies the Macdonald trough in the Sydney basin. Allowing for isostatic compensation and the effect of sedimentary rocks, the anomaly is determined to have an amplitude of 440 GU (μtms-2) and a width of 60 km. The anomaly is smoothed using cubic splines, FFT and IFFT. It is interpreted by a large mafic body of density 2.9 g cm-3 underlying the basin to a depth of 13.5 km. A 12 km wide zone with a small positive density contrast underlies the body within the lower crust.

The steep western boundary of the body represents a major basement fault underlying the Lapstone monocline and Kurrajong Fault System.

The anomaly is a member of the Meandarra Gravity Ridge which marks a zone of crustal extension within which dominant nature of intrusion is mafic in character.

© 1989 ASEG
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1989-03-01
2026-01-18

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References

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  8. Mayne, S. J., Nicholas, E., Bigg-Wither, A. L., Rasidi, J. S. & Raine, M. J. (1974), ‘Geology of the Sydney Basin – a review,’ Aust. Bur. Min. Resour. Geol. Geophys., Bull. No. 149.
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  11. Qureshi, I. R. & Miller, L. V. (1989), ‘A geophysical study of the Ben Bullen Plutonic Suite and its relationship with the origin of the Sydney basin’, 23rd Symp. Advances in the Study of the Sydney Basin, Proc, 163-170.
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  • Article Type: Research Article
Keyword(s): basement fault; crustal structure; gravity anomaly; Sydney Basin; tectonics

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