Precise zircon U-Pb dating of the Mesoproterozoic Gawler large igneous province, South Australia

Abstract

The Mesoproterozoic Gawler Range Volcanics and Benagerie Volcanic Suite of the Gawler Craton and Curnamona Province, South Australia, together with associated intrusive magmatism, define an intracontinental, subaerial large igneous province (LIP) preserving an estimated 110 000 km3 of volcanic rock, which hosts one of the world's largest orebodies, the Fe oxide-Cu-Au-U deposit at Olympic Dam, and numerous other related Cu-Au deposits. New high-precision Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry (CA-TIMS) U-Pb dates on volcanic zircons allow for regional correlations between stratigraphic units of the GRV and BVS, and an understanding of how magmatic styles, temperatures, composition and mantle source input evolve over the duration of the LIP. The new dates indicate that the entire volcanic province erupted over a geologically short time interval of less than 10 million years, from c. 1595 to 1586 Ma, culminating in a widespread, voluminous flood rhyolite province that erupted in less than 1.5 million years, and most likely in 260,000 years or less. This follows a pattern of volcanism that is similar in duration and volume to mafic and bimodal continental LIPs, of which the mafic-dominated Phanerozoic continental flood basalt provinces are the more common end member.