Ongoing exploration for a possible Cattlegrid type stratabound copper deposit over an area south-west of Lake Torrens included aerial magnetic and EM surveys, drill testing of EM anomalies by 47 percussion holes totalling 2086 m, a regional...
Ongoing exploration for a possible Cattlegrid type stratabound copper deposit over an area south-west of Lake Torrens included aerial magnetic and EM surveys, drill testing of EM anomalies by 47 percussion holes totalling 2086 m, a regional magnetic interpretation, detailed petrological and stratigraphic studies, ground magnetic and resistivity surveys (which also aimed to further delineate buried ?Tertiary palaeochannels near Pandurra Homestead), and the preparation of bedrock unit stratigraphic sequence / mineralisation cross sections and 1:50,000 scale lithostratigraphy interpretative maps. The petrography of 7 possible geosynclinal equivalents to the Mount Gunson shelfal rocks were examined (Sturt Tillite - Elizabeth Conglomerate; Tapley Hill Formation - Woocalla Dolomite; Tapley Hill Formation; Seacliff Sandstone - Whyalla Sandstone; Reynella Sandstone - Yudnapinna Siltstone; Brachina Formation - Tregolana Shale). A review of the igneous rocks occurring in the Pandurra area suggested that they are part of a Roopena Volcanics assemblage of mainly tholeiitic basic to intermediate extrusives (but with some late stage acid differentiates), as deduced from their intimate relationships and some recognised affinities with rock types from drillhole Roopena 1. This was a significant revision of the earlier company and government mappers' view at the time, which held that volcanic outcrop and subcrop on the western side of the EL 186 area, between Cariewerloo and Roopena homesteads, was the acidic Gawler Range Volcanics. Sample lithologies identified include basalt, andesite, trachyandesite, trachyte, rhyodacite, rhyolite and tuffaceous rhyolite. Small residual gravity anomalies were thought to be most likely related to intrusives and volcanic flows, and not to the Pandurra Formation. No structures of economic interest were defined.
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