Alkaline-silicate igneous complexes host a diversity of evolved rock types, ranging from silica-undersaturated (feldspathoid-normative) to silica-oversaturated (quartz-normative). These systems can host significant resources of critical metals, especially rare-earth elements (REEs), which are vital for the high-strength magnets used in green energy technologies. At present, however, the controls on compositional diversity within these complexes and the associated impacts on magmatic REE enrichment remain poorly quantified.
In this talk, I will highlight recent work integrating phase equilibria modelling with whole-rock geochemistry, mineral chemistry, and trace element partitioning to explore the petrogenesis of mineralised and barren alkaline-silicate complexes. I will demonstrate how crystallisation pressure, redox conditions, mafic magma recharge and crustal assimilation rates variably influence the development of major element compositional diversity, alongside the effects on trace element budgets. Case studies will feature the REE-mineralised Blatchford Lake Igneous Complex (Canada), the barren alkaline plugs of the Erongo Complex (Namibia), and various complexes across the Gardar Province (South Greenland), the latter home to the world-class Ilimmaasaq REE-HFSE deposit. Through this research project, we aim to resolve the fundamental petrologic processes that dictate whether an alkaline magmatic system becomes mineralised.
Venue
Seminar rooms
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