Tectonic links between the Gawler Craton and Curnamona province, southern Australia: Implications for reconstructions of Rodinia and Columbia
|Location||International Geological Congress,oslo 2008|
|Author||Szpunar, Michael; Hand , Martin; Barovich, Karin; Wade, Ben|
|Holding Date||08 October 2008|
The Southern Australian Proterozoic is dominated by the late Archaean-Mesoproterozoic Gawler Craton (GC) and the Paleo-Mesoproterozoic Curnamona Province (CP). These domains host some of the largest base metal ore bodies ever discovered including the giant Cu-U-Au-Ag-REE Olympic Dam and the Broken Hill Pb-Zn-Ag deposits. The two domains are also positioned on the south-eastern margin of Proterozoic Australia, which in the context of palaeogeographic reconstructions, forms a segment of a triple junction between Laurentia, Proterozoic Antarctica and Proterozoic Australia and a central location within the Proterozoic supercontinents Rodinia and Columbia. The Gawler and Curnamona Cratons therefore occupy an important location in the reconstruction of these Proterozoic supercontinents.
Whilst there has been a significant amount of work on the GC and CP as individual entities, little is known of the relationship between the domains. In this contribution we present new geochemical, geochronological and isotopic data to constrain provenance, magmatism and deformation of a series of poorly constrained, Palaeo-Mesoproterozoic basins that are positioned on the eastern margin of the Gawler Craton through to the western edge of Curnamona Craton in an attempt to understand the tectonic linkage between the two terrains. The data indicate a progressive development of Palaeoproterozoic basins with similar provenance of evolved crust (εNd(1.7Ga) = -3 to -7) and REE-enriched upper crust, compared with Post-Archean Average Australian Shale (PAAS). The data also indicate the basin system progressively youngs west to east from the eastern edge of the GC at ~1790Ma through to the CP at ~1710Ma, implying spatial and temporal linkages between the eastern GC and CP from as early as 1710 Ma. A younger, ~1600Ma tectonothermal event, similar in timing to the main orogenic event in the CP, has also been identified within the Barossa Complex, (an inverted basin sequence ~300km south west of the CP). The timing of this event is younger than the aforementioned ~1710Ma link between the GC and CP and therefore does not appear to be related to the joining of the domains. The new data do however, increase the extent of a major ~1600Ma tectonothermal event from the northern to the southern margin of eastern Australian Proterozoic. This orogenic belt forms an important, temporally constrained piercing point which as yet is largely unrecognized in Laurentia and Proterozoic Antarctica. This major tectonothermal event must be incorporated into in any reconstruction model of Columbia or Rodinia involving the eastern Australian Proterozoic at 1600Ma.