Crustal Structure and Ocean-Continent Transition Location on the South Australian Rifted Margin from Subsidence Analysis  


Authors / CoAuthors

Silva, R.A. | Kusznir, N. | Totterdell, J.M.

Abstract

Flexural backstripping applied to 5 seismic reflection lines has been used to constrain the distribution of lithosphere thinning, crustal structure and the location of the ocean-continent transition (OCT) of the southern Australian Bight Basin rifted margin. The amplitude of the anomalous subsidence in the southern margin of Australia was determined for each seismic line by means of residual depth anomalies (RDA) and included in all models. Sensitivity tests of predicted syn-breakup melt generated during lithosphere thinning and breakup were investigated assuming a magma-poor and a normal non-volcanic margin. The Bight Basin shows an apparent crustal segmentation between the Eyre-Recherche and the Ceduna-Recherche sub-basins. Whilst the lateral variation of lithosphere thinning in the Ceduna-Recherche sub-basin is gradual, in the Eyre-Recherche it is abrupt, predicting a highly extended continental crust underneath the Recherche sub-basin. Predicted ocean-continent transition (OCT) widths for the Bight Basin range from approximately 100 km to a maximum of 200 km, although the structure of the OCT itself is unclear. The predicted OCT determined from flexural backstripping compared with independent estimates of basement thickness derived from gravity inversion are in general agreement. Linear marine magnetic anomalies appear to be lying within the predicted OCT of the Bight Basin. If the magnetic anomalies are due to the presence of highly serpentinized peridotites and mafic bodies, the magnetic lineations cannot be used to constrain conventional seafloor spreading.

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nonGeographicDataset

eCat Id

70647

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  Custodian

ED  

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Commonwealth of Australia (Geoscience Australia)  
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia

Keywords

  • External PublicationScientific Journal Paper
( Theme )
  • continental margins
( Theme )
  • structural geology
( Theme )
  • sedimentary basins
( Theme )
  • marine
  • AU-SA
Australian and New Zealand Standard Research Classification (ANZSRC)
  • Earth Sciences
  • Published_Internal

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2010-06-30T00:00:00

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