Osmium isotopes and crustal sources for platinum-group mineralization in the Bushveld Complex, South Africa

T. E. McCandless, Joaquin Ruiz

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Abstract

Economic mineralization is found in the Merensky Reef and the UG2 and UG1 chromitites and includes osmium-bearing laurite (Ru, Ir, Os)S2. The laurite-bearing samples have 187Os/186Os ratios of 1.28-1.60, which are more radiogenic than predicted for mantle derived, 2.0 Ga Os(~0.9) and indicate a system-wide assimilation of crustal Os. The UG1 chromitite is stratigraphically the lowest and the least radiogenic (1.28), whereas the Merensky Reef is the highest and most radiogenic (1.41-1.60; Hart and Kinloch, 1989). Radiogenic Os from crustal assimilation in mantle-derived magmas or from hydrothermal fluids can account for these high isotopic ratios. The Os isotope data add to mounting evidence that PGEs in layered mafic intrusions may be derived from crustal sources and can no longer be considered as solely a product of mantle-derived magmatic processes. -from Authors

Original languageEnglish (US)
Pages (from-to)1225-1228
Number of pages4
JournalGeology
Volume19
Issue number12
DOIs
StatePublished - 1991

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osmium isotope
platinum
laurite
mineralization
mantle
reef
osmium
chromitite
platinum group element
isotopic ratio
hydrothermal fluid
isotope
economics
Africa
assimilation

ASJC Scopus subject areas

  • Geology

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Osmium isotopes and crustal sources for platinum-group mineralization in the Bushveld Complex, South Africa. / McCandless, T. E.; Ruiz, Joaquin.

In: Geology, Vol. 19, No. 12, 1991, p. 1225-1228.

Research output: Contribution to journalArticle

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