Geodynamic evolution of the Proterozoic Mount Isa terrain

Abstract

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.

The relative effects of deformation and thermal advection on fluid pathways in basin-related mineralization

“…1). This geometry is consistent with the onset of Zn-Pb deposition of the Mt Isa Block (O'Dea et al, 1997;Betts et al, 2003), and in more general terms can be representative of SEDEX or near surface base metal mineralisation. This scenario also provides a good template for understanding the potential mixing of near-surface and deeper derived fluids in many other deposit types e.g.…”

Sandstone Diagenesis in the Mount Isa Basin: An Isotopic and Fluid Inclusion Perspective in Relationship to District-Wide Zn, Pb, and Cu Mineralization

“…None of the illite separates analyzed have undisturbed 40 Ar/ 39 Ar spectrum and all samples have young initial apparent ages, indicating Ar loss caused by a thermal event. The most common plateau, pseudoplateau, and integrated ages obtained during this study range between 1442 ± 12 and 1607 ± 11 Ma (Table 8), a period that overlaps the Isan orogeny (Blake, 1987;Carr et al, 1996;O'Dea et al, 1997a;Perkins et al, 1999;Spikings et al, 2001;Golding et al, 2006). The younger ages, around 1450 Ma, have previously been attributed to the end of the Isan orogeny and reactivation of major fault zones related to post-Isan exhumation (Perkins et al, 1999;Spikings et al, 2001;Uysal et al, 2004).…”

Crustal architecture and geodynamics of North Queensland, Australia: Insights from deep seismic reflection profiling

“…Although intraplate development of these basins has been proposed (see Foster and Austin, 2008), a backarc tectonic setting is favoured by a number of authors Gibson et al, 2008). The Isan Orogeny at 1600 Ma to 1500 Ma inverted at least the youngest of the three basinal developments and has widespread expression across the province, with a complex history involving both north-south and east-west shortening (O'Dea et al, 1997;Blenkinsop et al, 2008). The Etheridge Province also records multiphase deformation and metamorphism between 1620 Ma and 1550 Ma (Withnall et al, 1997;Cihan et al, 2006;Withnall et al, 2009) (Glikson and Derrick, 1978;Wilson, 1978).…”

“…During this interval, polyphase deformation and metamorphism was experienced across the Mount Isa Province, including major approximately east-west contraction, which imparted the dominant meridional structural grain to the province (O'Dea et al, 1997;Blenkinsop et al, 2008) (Fig. 15f).…”