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Neoproterozoic (ca. 820–830 Ma) mafic dykes at Olympic Dam, South Australia: links with the Gairdner Large Igneous Province
journal contributionposted on 2023-05-18, 13:56 authored by Huang, Q, Vadim Kamenetsky, Jocelyn McPhieJocelyn McPhie, Ehrig, K, Sebastien MeffreSebastien Meffre, Maas, R, Thompson, J, Maya KamenetskyMaya Kamenetsky, Chambefort, I, Apukhtina, O, Hu, Y
A suite of basaltic to doleritic dykes (named the Olympic Dam dolerite) has been intersected in drill holes at the Olympic Dam iron oxide Cu–U–Au–Ag deposit in the Gawler Craton, South Australia. The dykes intrude the ca. 1600 Ma Roxby Downs Granite as well as the Olympic Dam Breccia Complex, and range from several centimetres to over 100 m in width, strike NW and dip subvertically. Clinopyroxene and plagioclase are the major minerals, together with accessory apatite and Ti-magnetite. Magmatic apatite crystals in medium-grained doleritic dykes have been dated by LA-ICPMS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry), and yielded a U–Pb age of 825 ± 18 Ma. The Olympic Dam dolerite has invariably been altered. Secondary apatite and titanite crystals from post-magmatic veinlets cutting the same dykes give similar results of 821 ± 15 Ma and 817 ± 11 Ma, respectively. All these results are, within error, coincident in age with the Gairdner Dyke Swarm, the longest dyke swarm (∼1000 km in length) in Australia. The Olympic Dam dolerite shows similar compositional trends and variations to the Gairdner Dyke Swarm, especially in terms of the relatively immobile High Field Strength Elements (HFSE) and Rare Earth Element (REE). We conclude that the Olympic Dam dolerite belongs to the Gairdner Dyke Swarm, expanding its known extent and compositional range. The Gairdner Dyke Swarm is a major component of the ca. 820 Ma Gairdner Large Igneous Province (LIP) generated during the break-up of the supercontinent Rodinia. The ca. 1070 Ma Warakurna and the ca. 820 Ma Gairdner LIP in Australia are compositionally distinct, whereas the Gairdner LIP and LIP and mafic suites associated with the break-up of Rodinia in South China and North America are broadly similar. This provides geochemical support for a Gairdner LIP origin for some mafic suites, in particular the Beda Volcanics in South Australia, and for a juxtaposition of South China, South Australia and North America in the tectonic reconstruction of Rodinia at ca. 820 Ma.
Australian Research Council
BHP Billiton Olympic Dam Corporation
Publication titlePrecambrian Research
Department/SchoolSchool of Natural Sciences
PublisherElsevier Science Bv
Place of publicationPo Box 211, Amsterdam, Netherlands, 1000 Ae
Rights statement© 2015 Elsevier B.V. All rights reserved.