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Graham Begg - Mineral Systems in context: Dynamic processes and a 4D Earth

Ore deposits are the product of Mineral systems that operate at the lithosphere-scale and are controlled by the global geodynamic system. This week's talk with Graham Begg will focus on Ni-Cu-PGE, Cu-Mo, Cu-Au, and Au deposits. The relationship of Ni-Cu-PGE deposits to craton margins is well established. Less well appreciated is the link of these deposits to the supercontinent cycle peak, core-mantle boundary processes, regional compression, and stress switches. Porphyry Cu deposits are strongly linked with the most compressive sections of convergent margins, where ordinary arc melts are transformed into highly hydrous fractionated melts fertile for high-grade mineralisation. Gold fertility is a mantle-derived property whereby low-degree melts scavenge gold from the convecting mantle and store the metal in veinlets in areas of metasomatic alteration, generally within the continental mantle. Tectonic triggers can harvest the contents of these veinlets, creating volatile-rich melts that carry the gold into the overlying crust. Tectonic and lithospheric reconstructions demonstrate the spatial and temporal context for Archean and Paleoproterozoic deposits.