ler ranges, coincident with the mode that is around the median value of the whole data set. Together with textural evidence, sulfide trace element data, and gold occurrence, the data demonstrate that metamorphism has gradually homogenized the early sulfur, accompanied by the segregation of quartz and the release of gold from the lattice of early pyrite and its re-precipitation as inclusions in later pyrite. The sulfur isotopic compositions of sulfides in Sukhoi Log, and many other major orogenic gold deposits hosted in sedimentary rocks of various ages, show a pattern generally parallel to the seawater sulfate curve through geologic time, indicating that the sulfur in most sediment-hosted orogenic gold deposits was probably also originally from the reduction of seawater sulfate. Chang et al. conclude that sulfidation and gold mineralization in many sediment-hosted orogenic gold deposits was early during basin evolution when seawater was the principal active fluid, rather than later during or after basin inversion, as proposed in current models.
Multiple sulfur isotopes reveal a magmatic origin for the Platreef platinum group element deposit, Bushveld Complex, South Africa
Sarah C. Penniston-Dorland et al., Department of Geology, University of Maryland, College Park, Maryland 20742, USA. Pages 979-982.
Models for the formation of platinum group element (PGE) ore deposits commonly require that magma incorporate parts of the wall rock into that which they intrude to provide sulfur. This externally derived sulfur is thought to be necessary to concentrate PGEs into the high concentrations found in these ore deposits. Using a relatively new analytical tool, the analysis of multiple isotopes of sulfur (32S, 33S, and 34S), Penniston-Dorland et al. demonstrate that sulfur within the two-billion-year-old Platreef PGE ore horizon of the Bushveld Complex in South Africa was not derived from local wall rock, and instead must have been brougPage: 1 2 3 4 5 6 7 8 9 Related biology news :1
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