GSWA Open Day 2024 | A Li-pegmatite paradigm consistent with Western Australia’s Archean geology

GSWA Open Day 2024 | A Li-pegmatite paradigm consistent with Western Australia’s Archean geology
Hugh Smithies, Manager Geoscience
Mapping and Mineral
Systems
Lithium is an essential part of the global shift towards clean energy. Most of the world's lithium currently comes from pegmatites that formed during the Archean eon. However, we don’t fully understand how these pegmatites formed, as most studies focus on pegmatites from different regions, which may not be relevant to Archean settings. To improve this, the Geological Survey of Western Australia (GSWA) is collecting a large amount of geochemical data from granites in the Yilgarn and Pilbara Cratons. They are focusing on areas that are close in space and time to lithium-rich pegmatites.
This new dataset, combined with regional maps, shows that S-type granites and possible sources of metasedimentary melt found in studies of lithium pegmatites from younger periods are not present in the Australian Archean terrains. Early analysis of the data suggests that other sources, more consistent with how Archean granites and greenstone belts evolved, could be involved.
In this presentation, we will explain why we reject the "sediment source" models for lithium pegmatite formation. We will also present the data and ideas that lead us to propose that the biotite-altered root zones of greenstone belts might be a better source for lithium pegmatites.
#GSWA2024