Multi-scale analysis of Proterozoic shear zones: An integrated structural and geophysical study

John R. Stewart*, Peter G. Betts, Alan S. Collins, Bruce F. Schaefer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

Structural mapping of poorly exposed shear zone outcrops is integrated with the analysis of aeromagnetic and Bouguer gravity data to develop a multi-scale kinematic and relative overprinting chronology for the Palaeoproterozoic Tallacootra Shear Zone, Australia. D2 mylonitic fabrics at outcrop record Kimban-aged (ca. 1730-1690 Ma) N-S shortening and correlate with SZ1 movements. Overprinting D3 sinistral shear zones record the partitioning of near-ideal simple shear and initiated Riedel to regional-scale SZ2 strike-slip on the Tallacootra Shear Zone (SZ2). Previously undocumented NE-SW extension led to the emplacement of aplite dykes into the shear zone and can be correlated to the (ca. 1595-1575 Ma) Hiltaba magmatic event. D4 dextral transpression during the (ca. 1470-1450 Ma) Coorabie Orogeny reactivated the Tallacootra Shear Zone (SZ2-R4) exhuming lower crust of the northwestern Fowler Domain within a positive flower structure. This latest shear zone movement is related to a system of west-dipping shear zones that penetrate the crust and sole into a lithospheric detachment indicating wholesale crustal shortening. These methods demonstrate the value of integrating multi-scale structural analyses for the study of shear zones with limited exposure.

Original languageEnglish
Pages (from-to)1238-1254
Number of pages17
JournalJournal of Structural Geology
Volume31
Issue number10
DOIs
Publication statusPublished - Oct 2009
Externally publishedYes

Keywords

  • Aeromagnetics
  • Forward modeling
  • Gawler Craton
  • Gravity
  • Proterozoic
  • Shear zone

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