This project is focussed on aspects of granites in Tasmania, especially in how they relate to mineralisation. Petrogenetic questions involving the genesis of I- and S-type granites, pluton construction, and the magmatic-hydrothermal transition are being addressed. Colin Jones successfully completed his confirmation of candidature for his PhD, as well as most of his fieldwork and sample collection in 2019. He has completed a significant portion of his geochronology and whole-rock geochemistry analytical campaign, as well as finished O-isotope analyses on zircon at ANU. Colin published an extended abstract for the Sn-W-Critical Metals and Associated Magmatic Systems conference held in Tinaroo, Queensland, where he presented a poster on the geochronology of Bluestone Bay, Tasmania. David Cooke and Wei Hong also published extended abstracts for the Sn-W-Critical Metals and Associated Magmatic Systems conference and gave oral presentations on aspects of the magmatic-hydrothermal transition in Tasmanian granites. Wei submitted a fluid inclusion manuscript to Economic Geology in 2019, which should be published in 2020. Colin gave an oral presentation at the Tasmanian Geoscience Forum in St Helens, Tasmania, where he also ran a conference field trip to Bluestone Bay, Freycinet.

The project is investigating magmatic-hydrothermal transition textures in a number of granite plutons throughout Tasmania, targeting barren, mineralised, and both S- and I-type granites. Petrogenetic questions involving pluton construction, magma mingling and schlieren are being addressed, and these features are being linked back to metallogenesis and exploration significance.

Wei Hong completed a manuscript for American Mineralogist on quartz UST textures in western Tasmanian granites, to be published early in 2019. Colin Jones commenced a PhD study on the petrogenesis of eastern Tasmanian granites in November 2018. He completed several field excursions, presented a poster at the GSA Earth Sciences Student Symposium and an oral presentation at the AusIMM/AIG/GSA Tasmania Geoscience Forum. His PhD study involves collaboration with researchers from Mineral Resources Tasmania and Geoscience Australia.

Emmet O’Keefe completed an Honours study of the genesis of the Trial Harbour skarn in western Tasmania. Emmet unravelled a complicated skarn paragenesis that included early prograde anhydrous calcic and iron-magnesian skarn assemblages that were overprinted by several retrograde hydrous assemblages. Minor Zn-Pb mineralisation and an unusual association with Ni were paragenetically constrained. Through careful mineral mapping and Ar-Ar and U-Pb age determinations, Emmet was able to relate the complex and unusual skarn formation with the emplacement of the red Heemskirk granite into host rocks with variable provenances, including ultramafics, dolostones and wackes.

This Honours project aimed to describe the granitic rocks of Bluestone Bay, Tasmania, including the documentation of the magmatic-hydrothermal paragenesis, the determination of absolute ages of magmatism, the determination of magmatic provenance and intrinsic parameters, and to construct a genetic and exploration model for the region. Several trips to the field area were conducted during the year in order to conduct outcrop mapping, collect samples and observe rock relationships. Drill core logging was conducted on a 1,000 m drill hole stored at Mineral Resources Tasmania, from which additional sampling was conducted and rock relationships were observed. Samples were subject to a variety of analytical techniques, including whole rock geochemistry, U-Pb geochronology, and other mineral chemistry techniques (e.g., XRD, LA-ICP-MS, SEM).

The study found that the oldest intrusions at Bluestone Bay were 400 million-year-old granodiorites that had been crosscut by magmatic-hydrothermal transition texture-bearing alkali-feldspar granite at 388 Ma. The alkali-feldspar granite generated hydrothermal alteration, weak mineralisation and a variety of aplite/pegmatite dikes. The project involved the calculation of temperature and depth of emplacement constraints of the granitic intrusions as well as fingerprinting the productive intrusions within the region.