Noble Metal Enrichment Processes in the Merensky Reef, Bushveld Complex 论文

摘要

Reef for platinum-group elements (PGEs), Re and Au using laser The enrichment of noble metals in layered gabbroic ablation-inductively coupled plasma mass spectrometry and synthetic intrusions to form stratiform Merensky-type ore horizons pyrrhotite standards annealed with known quantities of noble metals. is an extremely efficient yet poorly understood process. Os, Ir and Ru reside in solid solution in pyrrhotite and pentlandite, Metal enrichment must be related to the formation of Rh and part of the Reef's Pd in pentlandite, whereas Pt, Au, Re magmatic layering, as the ore horizons form an integral and some Pd form discrete phases. Olivine and chromite, often part of the magmatic stratigraphies of their host insuspected to carry Os, Ir and Ru, are PGE free. All phases analysed trusions. Metal concentration is also related to the prescontain noble metals as discrete micro-inclusions with diameters ence of magmatic sulphides, because the noble metals are either dissolved in base metal sulphides or occur as typically <100 nm. Inclusions in sulphides commonly have the discrete noble mineral phases intergrown with sulphides element combinations Os-Ir-Pt and Pt-Pd-Au. Inclusions in Few inclusion Ballhaus & Ulmer, 1995).