This field guidebook provides brief geological summaries to sites in South Australia that were visited during the 2006 Broken Hill Exploration Initiative pre-conference excursion. Figures show the location of the field area and approximate...
This field guidebook provides brief geological summaries to sites in South Australia that were visited during the 2006 Broken Hill Exploration Initiative pre-conference excursion. Figures show the location of the field area and approximate location of the geological sites. For a more detailed overview of the geology the user is referred to the draft report ?Geology of the Olary and Mulyungarie Domains, Curnamona Province, South Australia. 2006? (Conor, 2006). Radiometric ages quoted are from Page et al. (in prep.), unless specified otherwise. The geological site layout of this BHEI guidebook is different from that used in previous versions, in that the information for each site is compiled in the form of a fact sheet. The intention of this scheme is to enable the formation of a library of geological sites that can be continually updated and added to. The Curnamona Province is divided into the following eight domains: - Moolawatana Domain (new name) includes basement rocks outcropping in the Mount Painter and Mount Babbage Inliers, and a shallowly buried easterly extension of these rocks. - Erudina Domain (new name) is the deeply buried and poorly known basement beneath the Cambrian Moorowie Sub-basin. - Quinyambie Domain (new name) is the deeply buried basement beneath the Cambrian Yalkalpo Sub-basin. - Mudguard Domain (new name) in the Curnamona Province is characterised by a sheet of flat-lying, early Mesoproterozoic (~1580 Ma) A-type felsic and mafic volcanics (Giles and Teale, 1979) and minor unmetamorphosed sediments. - Olary Domain (renamed by Laing, 1996 from Olary Block) is recognised by a restricted development of the Broken Hill Group, and by the presence of the oldest known part of the Willyama Supergroup, the Curnamona Group. - Mulyungarie Domain (new name) is characterised by thick sulphidic successions, and is possibly transitional between the Olary and Broken Hill Domains. Almost entirely blanketed by younger sediments, the Mulyungarie Domain has poorly defined boundaries, apart from its eastern margin at the Mundi Mundi Fault. - Broken Hill Domain (renamed by Laing, 1996 from Broken Hill Block) is characterised by the maximum development of the lode-bearing stratigraphy of the Broken Hill Group. Much of the western boundary is defined by the Mundi Mundi Fault, but, at the southern end of the fault, the boundary diverges in a southwesterly direction (Crooks, 2001). The Broken Hill Domain thus crops out in the Broken Hill, Euriowie, Poolamacca, Mt Woowoolahra and Nardoo Inliers, as well as in the south-eastern and central eastern portions of the Kalabity Inlier. - Redan Domain is a region of high magnetic intensity lying south-east of the Broken Hill Domain, and it contains the oldest rocks known from the Broken Hill Inlier. Different aspects of geology of the Olary region were viewed during the two days of fieldwork, and the current understanding of the lithostratigraphy of the Olary Domain was explained to excursion participants. A prime aspect to which their attention was directed at the outset was to view the geology of the eastern part of Bimbowrie Station via some well-known geological sites. This is an area which was made classic by Sir Douglas Mawson (Mawson, 1912), and it has enriched the knowledge of students of geology ever since. In variance to previous field trips made in this area, a theme was followed that considered the potential for growth faulting to control facies distribution within the Willyama Supergroup, especially the westward extension of Broken Hill Group rocks into the Olary Domain. Demonstration of the presence of Broken Hill Group equivalent stratigraphy was extremely important because it countered the belief that this critically mineralised part of the succession is missing from the Olary Domain.
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