Musgrave Province Reconnaissance Using TerraneChronÔ

Abstract

PIRSA has begun regional geological mapping of the high-grade, metamorphic Musgrave Province, which is the last Proterozoic terrane in Australia to undergo modern geological analysis. GEMOC?s TerraneChron? methodology was trialed on the drainage network across the province, to provide a U-Pb age spectrum and information on the source of the parent magma obtained from zircon Hf-isotopic composition. This would provide a framework to direct further geological investigations. One sample has identified a 1630Ma population with a strong component of possibly inherited 2800Ma zircon. Neither of these ages have been recognised in the province before and the Archean zircons are one of the oldest populations identified in SA. Further investigation of the drainage area suggests that the zircon is derived from a fault-bounded domain consisting predominantly of granitic gneiss. Hafnium isotope data indicate juvenile mantle-derived sources for all the samples so far analysed with minor reworking of older Archean crust supported by the presence of the inherited Archean population. Trace element analysis of the zircons shows the greater majority to be derived from felsic igneous rocks (80-90%). A small group of mafic derived zircons was found within the Archean population. Possible tectonic links with the Arunta and Curnamona Provinces are suggested by these ages. The Leibig Orogeny (1640Ma) on the southern edge of the Arunta region is the closest area of similar age, but shows no inherited Archean zircon.