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Lifting the veil on the Geological Dark Ages: the search for Hadean crust on Earth

Yilgarn and Pilbara cratons, Western Australia

This project aims to develop the first comprehensive picture of the earliest growth history of the Australian continent as preserved in the Yilgarn and Pilbara cratons- in particular to locate, characterize, and define the areal distribution of Hadean crust.  

This will be achieved by a thorough field and analytical program targeting rock packages and gneiss complexes of various ages in these areas- including the Narryer gneisses of the Yilgarn Craton, components of which are at least as old as 3.73 Ga. The Narryer gneisses are the oldest rocks recognized in Australia to date and constitute one of the most ancient crustal fragments on Earth. Together with the oldest rocks in the Pilbara Craton (~3.66 Ga tonalite gneiss), they constitute a critical, but under-studied piece of the global puzzle concerning the growth and evolution of the earliest continents. The analytical program will involve geochronology, measurement of isotope tracers in robust mineral archives (Lu-Hf and O isotopes in zircon, Sm-Nd isotopes in titanite) by in situ and conventional solution techniques, and measurement of both long-lived (Lu-Hf, 143Nd-147Sm) and short-lived (142Nd-146Sm) radiogenic isotope systems from the corresponding whole rocks. This is a powerful approach that will combine the combine the spatial resolving power of microanalysis with the high precision afforded by the solution analysis of minerals and whole rocks. The project will utilize the world-class mass spectrometry facilities being established at the University of Western Australia and the Australian National University.