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 language | English |
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Pages (from-to) | 1-21 |
Number of pages | 21 |
Journal | Australian Journal of Earth Sciences |
Volume | 57 |
Issue number | 1 |
DOIs | |
Publication status | Published - Feb 2010 |
Externally published | Yes |
Keywords
- Isan orogeny
- Mylonite
- Riedel shear
- Strain partitioning
- Strike-slip faulting
- Transpression