Constraining alteration in the buried Benagerie ridge, Curnamona province South Australia

Simpson, Alex1, Glorie, Dr Stijn1, Hand, Prof Martin1, Reid, Dr Anthony2, Gilbert, Dr Sarah3

1The University Of AdelaideMineral Exploration Cooperative Research Centre, School of Earth & Environmental Sciences, University of Adelaide, Adelaide, Australia, 2Mineral Exploration Cooperative Research Centre, Geological Survey of South Australia, Adelaide, Australia, 3Adelaide Microscopy, University of Adelaide, Adelaide, Australia

The Curnamona province, situated at the border between SA and NSW is a piece of Paleoproterozoic crust that is separated from the Gawler craton by the Adelaide Rift Complex. This geological region is highly prospective for a variety of mineralisation types, including the Pb-Zn-Ag (e.g. the world class Broken Hill deposit), and iron-oxide copper gold (IOCG) (e.g. Kalkaroo and Portia deposits) [Conor and Preiss, 2008]. The Benagerie ridge volcanic suite (BVS) sits in the centre of the province and is a correlative of the Gawler Range Volcanics (GRV), host of the world class Olympic Dam IOCG deposit [Wade et al., 2012]. The province has undergone multiple episodes of deformation, with the most important events considered to be the ~1600 Olarian Orogeny and the ~500 Delamerian orogeny  [Conor and Preiss, 2008], with some evidence for ~830 Ma dyke emplacement [Wingate et al., 1998]. Additionally, multiple episodes of alteration and mineralisation have occurred, particularly regional scale albitisation [Skirrow et al., 1999]. Limited direct constraints exist on the timing of these episodes, with most thought to have occurred prior to the Olarian Orogeny.

LA ICP MS elemental and isotopic mapping, combined with LA ICP MS U-Pb geochronology, and geochemistry provide insight into multiple episodes of post-Olarian fluid alteration, including ~820 Ma albitisation and mineralisation in the BVS. We further demonstrate the utility of U-Pb geochronology applied to hydrothermal apatite, titanite, calcite and magnetite to constrain the timing of episodes of fluid alteration.

Conor, C. H. H., and W. V. Preiss (2008), Understanding the 1720–1640Ma Palaeoproterozoic Willyama Supergroup, Curnamona Province, Southeastern Australia: Implications for tectonics, basin evolution and ore genesis, Precambrian Research, 166(1-4), 297-317.

Skirrow, R., R. Maas, and P. M. Ashley (1999), New age constraints for Cu-Au(-Mo) mineralisation and regional alteration in the Olary-Broken hill region, AGSO Research Newsletter, 31.

Wade, C. E., A. J. Reid, M. T. D. Wingate, E. A. Jagodzinski, and K. Barovich (2012), Geochemistry and geochronology of the c. 1585Ma Benagerie Volcanic Suite, southern Australia: Relationship to the Gawler Range Volcanics and implications for the petrogenesis of a Mesoproterozoic silicic large igneous province, Precambrian Research, 206-207, 17-35.

Wingate, M. T. D., I. H. Campbell, W. Compston, and G. M. Gibson (1998), Ion microprobe U–Pb ages for Neoproterozoic basalticmagmatism in south-central Australia and implications for thebreakup of Rodinia, Precambrian Research, 87, 135-159


Alex Simpson is a PhD student at the University of Adelaide with interests in radiometric dating utilising novel and emerging laser ablation methods applied to   geochronology on non-traditional minerals, with applications for constraining alteration and remobilisation events.

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