Tectonic affinities of the Houghton Inlier, South Australia: U – Pb and Hf-isotope data from zircons in modern stream sediments

Abstract

The integrated in situ microanalysis of Pb and Hf isotopic compositions of zircon (TerraneChron® methodology) has been applied to detrital zircons from locally derived stream sediments in the South Para River, which samples the Houghton Inlier, South Australia. The zircons record two major events: an igneous event at 1718±8 Ma and a metamorphic event at 1625±9 Ma. The igneous event is of broadly similar age to syndepositional magmatism associated with the lower Willyama Supergroup of the Curnamona Province and syn-Kimban Orogeny intrusives of the eastern Gawler Craton. The later metamorphic event is of comparable age to the Olarian Orogeny in the Curnamona Province and to magmatic and metamorphic events in the central to western Gawler Craton. The combination of U – Pb dating and Hf-isotope data provides an additional tool to overcome ambiguities in correlating terranes with similar U – Pb ages. The Hf-isotopic compositions of the Houghton Inlier zircons and their model ages of 2.5 – 2.4 Ga suggest a closer match with the rocks of the Gawler Craton.