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Pre-existing basement structure and its influence on continental rifting and fracture zone development along Australia's southern rifted margin

Journal Article


Abstract


  • Palaeogeographical reconstructions of the Australian and Antarctic margins based on matching basement structures are commonly difficult to reconcile with those derived from ocean-floor magnetic anomalies and plate vectors. Following identification of a previously unmapped crustal-scale structure in the southern part of the early Palaeozoic Delamerian orogen (Coorong Shear Zone), a more tightly constrained plate reconstruction for these margins is proposed. This reconstruction places the Coorong Shear Zone opposite the Mertz Shear Zone in Antarctica and lends itself to a revised interpretation of continental rifting along Australia's southern margin in which rift basin architecture, margin segmentation and the formation of ocean-floor fracture zones are all linked to pre-existing basement structure and the reactivation of a few deep-rooted crustal structures inherited from the Delamerian orogeny in particular. Reactivation of the Coorong Shear Zone and other basement structures (Avoca-Sorell Fault Zone) during the earlier stages of rifting was accompanied by the partitioning of extensional strain and formation of late Jurassic-Early Cretaceous normal faults and half-graben in the Bight and otway basins with opposing NE-SW and NW-SE structural trends. Previously, the Mertz Shear Zone has been correlated with the Proterozoic Kalinjala Mylonite Zone in the Gawler Craton but this positions Australia 300-400 km too far east relative to Antarctica prior to breakup and fails to secure an equally satisfactory match in both basement geology and the superimposed extension-related structures.

UOW Authors


  •   Gibson, G M. (external author)
  •   Totterdell, J (external author)
  •   Lloyd White
  •   Mitchell, C (external author)
  •   Morse, M P. (external author)
  •   Stacey, A R. (external author)
  •   Whitaker, A (external author)

Publication Date


  • 2013

Citation


  • Gibson, G. M., Totterdell, J. M., White, L. T., Mitchell, C. H., Morse, M. P., Stacey, A. R. & Whitaker, A. (2013). Pre-existing basement structure and its influence on continental rifting and fracture zone development along Australia's southern rifted margin. Journal of the Geological Society, 170 (2), 365-377.

Scopus Eid


  • 2-s2.0-84875025470

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/4377

Number Of Pages


  • 12

Start Page


  • 365

End Page


  • 377

Volume


  • 170

Issue


  • 2

Abstract


  • Palaeogeographical reconstructions of the Australian and Antarctic margins based on matching basement structures are commonly difficult to reconcile with those derived from ocean-floor magnetic anomalies and plate vectors. Following identification of a previously unmapped crustal-scale structure in the southern part of the early Palaeozoic Delamerian orogen (Coorong Shear Zone), a more tightly constrained plate reconstruction for these margins is proposed. This reconstruction places the Coorong Shear Zone opposite the Mertz Shear Zone in Antarctica and lends itself to a revised interpretation of continental rifting along Australia's southern margin in which rift basin architecture, margin segmentation and the formation of ocean-floor fracture zones are all linked to pre-existing basement structure and the reactivation of a few deep-rooted crustal structures inherited from the Delamerian orogeny in particular. Reactivation of the Coorong Shear Zone and other basement structures (Avoca-Sorell Fault Zone) during the earlier stages of rifting was accompanied by the partitioning of extensional strain and formation of late Jurassic-Early Cretaceous normal faults and half-graben in the Bight and otway basins with opposing NE-SW and NW-SE structural trends. Previously, the Mertz Shear Zone has been correlated with the Proterozoic Kalinjala Mylonite Zone in the Gawler Craton but this positions Australia 300-400 km too far east relative to Antarctica prior to breakup and fails to secure an equally satisfactory match in both basement geology and the superimposed extension-related structures.

UOW Authors


  •   Gibson, G M. (external author)
  •   Totterdell, J (external author)
  •   Lloyd White
  •   Mitchell, C (external author)
  •   Morse, M P. (external author)
  •   Stacey, A R. (external author)
  •   Whitaker, A (external author)

Publication Date


  • 2013

Citation


  • Gibson, G. M., Totterdell, J. M., White, L. T., Mitchell, C. H., Morse, M. P., Stacey, A. R. & Whitaker, A. (2013). Pre-existing basement structure and its influence on continental rifting and fracture zone development along Australia's southern rifted margin. Journal of the Geological Society, 170 (2), 365-377.

Scopus Eid


  • 2-s2.0-84875025470

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/4377

Number Of Pages


  • 12

Start Page


  • 365

End Page


  • 377

Volume


  • 170

Issue


  • 2