Portrait of a reference material: Zircon production in the Middledale Gabbroic Diorite, Australia, and its implications for the TEMORA standard

Abstract

The Middledale Gabbroic Diorite (MGD) in New South Wales, Australia, is host to the internationally distributed TEMORA 2 zircon reference material and its prototype, TEMORA 1. The original characterisation of the source of the reference zircons revealed that the more altered TEMORA 2 host rock contains an order of magnitude more zircon than the TEMORA 1 host, despite similar bulk-rock Zr concentrations. Although TEMORA 1 and 2 preserve the same U-Pb age, they are variable in oxygen isotope composition.In this study, petrographic observations in concert with bulk-rock and mineral geochemistry and zircon U-Pb geochronology have been applied to new samples of the MGD to investigate the link bet..