Wed 18th August 2021 @ 12:00 nn in 312.222 and online via Webex (meeting #: 1849 67 0138 and password: ZDtDZNaZ374)
Abstract:
The limited preservation of ancient crustal material poses a challenge for understanding the composition of Earth’s early crust. As a result of poor preservation and near-ubiquitous overprinting by later geological events, deciphering the early evolution of our planet often relies on the isotopic composition of resistive minerals, such as zircon. Although the isotopic information recorded by zircon grains has proved an invaluable asset to workers seeking to understand the geological evolution of the Earth, it is limited by the range of elements easily incorporated into the structure of the mineral. One way to overcome these limitations is by analysing inclusions of other minerals that were trapped within the zircon during crystallisation. Apatite has great potential in this respect, as it is commonly found as inclusions in magmatic zircon and records a variety of useful isotopic information. Here I present a new approach for investigating igneous petrogenesis and crustal evolution by combining 87Sr/86Sr measurements of apatite inclusions with U–Pb and Hf isotope analysis of their host zircon crystal. The Sr isotope information contained in the apatite can be accessed by applying a novel SIMS technique we developed for this purpose. Case studies applying this new approach to Archean igneous rocks from West Greenland and the Narryer Terrane (northern Yilgarn) demonstrate how this can be used to understand the evolution of these key localities, with implications for both regional geology and the growth of the continental crust.
Short bio:
Jack is an isotope geochemist and geochronologist. His current work is part of a Discovery Project (DP190103849) awarded to Pete Kinny, Alexander Nemchin, and Aaron Cavosie. Prior to his current postdoctoral position at Curtin, he completed a PhD at the University of Adelaide focussed on understanding the development of intracontinental mountain ranges in Central Asia via low-temperature thermochronology.
