Cloncurry fault zone: Strain partitioning and reactivation in a crustal-scale deformation zone, mt isa inlier

J. R. Austin, T. G. Blenkinsop

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

The Cloncurry Fault Zone is a north-northwest-trending zone of complex deformation over 100 km long and up to 7 km wide near the eastern edge of the Mt Isa Inlier. The zone includes mylonites in an anastomosing shear-zone system with variably plunging mineral lineations within a north-northwest subvertical girdle that formed synchronously with north-northwest- and south-southeast-plunging folds. No clear overprinting of lineations in different orientations is observed, and the complexity of the penetrative fabrics can be attributed to strain partitioning during east-northeast contraction, rather than requiring amore complex history of overprinting relations. The mylonites formed at temperatures of 350-5008C, below the ̃6508C metamorphic peak that occurred during the regional D2 event, and they are superimposed on Maramungee-aged granites (1555-1545 Ma), implying that the majority of fabrics formed during D3. D3 was followed by the development of a D4 sinistral Riedel strike-slip fault system involving east-southeast contraction, which was coincident with massive Na-Ca alteration and brecciation within the zone. Reactivation with a normal component of movement occurred some time after the Jurassic. The Cloncurry Fault Zone is a crustal-scale feature of the Mt Isa inlier that records strain partitioning and a deformation history lasting over 1.5 Ga.

Original languageEnglish
Pages (from-to)1-21
Number of pages21
JournalAustralian Journal of Earth Sciences
Volume57
Issue number1
DOIs
Publication statusPublished - Feb 2010
Externally publishedYes

Keywords

  • Isan orogeny
  • Mylonite
  • Riedel shear
  • Strain partitioning
  • Strike-slip faulting
  • Transpression

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