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Australian Geodynamics Cooperative Research Centre, VIEPS, Department of Earth Sciences, Monash University, Clayton, Vic 3168, Australia
1 School of Applied Geology, Curtin University, GPO Box U 1987, Perth, WA 6001, Australia
2 MIM Exploration Pty Ltd, GPO Box 1042, Brisbane, Qld 4001, Australia
The Proterozoic Mount Isa terrain records the effects of four periods of intraplate tectonism. The c. 1870 Ma Barramundi Orogeny was characterized by a massive felsic magmatic event, and global correlations suggest a physical link between Australia and Laurentia at this time. Thereafter, the terrain underwent an extensional history spanning 200 Ma involving repeated episodes of rifting, post-rift subsidence and associated depositional and magmatic phases. This protracted rifting history resulted in a cumulative stratigraphic thickness of up to 25 km above attenuated continental crust. Rifting was interrupted prior to the formation of ocean crust by the compressional Isan Orogeny (1590–1500 Ma). The Isan Orogeny was synchronous with low-pressure high-temperature metamorphism and widespread metasomatism. In the waning stages of shortening, the Mount Isa terrain evolved into a wrench system characterized by an extensive network of strike-slip faults. The current level of exposure in this terrain provides spectacular examples of superimposed rifts, basin inversion, and wrench geometries developed at middle to upper crustal levels.
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  S. McLaren and M. Sandiford Long-term thermal consequences of tectonic activity at Mount Isa, Australia: Implications for polyphase tectonism in the Proterozoic Geological Society, London, Special Publications, 2001; 184: 219 - 236. [Abstract] [PDF]
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