Sulfides in the upper mantle: controls over the chalcophile element budget in magmatic systems

Dr. Kate Kiseeva, Department of Earth Sciences, University of Oxford, UK

 

Ekaterina S. Kiseeva1, Raúl O. C. Fonseca2, Duane J. Smythe1

1Department of Earth Sciences, University of Oxford, OX1 3AN

2Steinmann Institut, Universität Bonn, 53115 Bonn, Germany

Sulfides are common accessory minerals in the Earth’s interior. They are observed in the upper mantle peridotites and oceanic basalts, in mantle xenoliths, and are also the most common mineral inclusion in diamonds. Despite sulfur being a minor component in the mantle, present at a concentration of ~150-300 parts per million (ppm) S in the bulk silicate Earth (e.g. Palme and O’Neill 2013), sulfides are nonetheless very important phases as many elements have a strong affinity for sulfur. These elements, termed chalcophile (or sulfur-loving, Fig.1), are concentrated in sulfides, which can then control their behavior during magmatic processes (Barnes et al., this issue).

Most chalcophile elements (some of which are also siderophile) are economically important metals; ten of these are the most valuable metals in the world (In, Re, Au, Ag and PGE). In Earth’s crust these elements are typically found associated with base metal sulfides, and sulfide deposits are mined extensively as a result. In addition to their economic importance, residual sulfides exert a strong control on the budget of chalcophile elements during partial melting and crustal differentiation and hence have a profound effect on trace element concentrations found in erupted magmas.

In this article, we explore the occurrence of sulfides in the Earth’s mantle, and in particular, the role of sulfides in the partitioning of chalcophile elements in magmatic systems, and the abundance of such elements in mantle-derived silicate melts.


תאריך 11/12/2016 10:30 12:00
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