Trace-element partitioning between synthetic potassic-richterites and silicate melts, and contrasts with the partitioning behaviour of pargasites and kaersutites
Trace-element partitioning between synthetic potassic-richterites and silicate melts, and contrasts with the partitioning behaviour of pargasites and kaersutites (in Special issue dedicated to the memory of Luciano Ungaretti, Maria Chiara Domeneghetti (prefacer))
European Journal of Mineralogy (April 2003) 15 (2): 329-340
Solid/liquid partition coefficients for LILE, HFSE, REE, Pb, Th, U and selected transition elements (Sc, V) were determined by SIMS on potassic-richterites synthesized at upper mantle conditions (1.4 GPa and 800-1020 degrees C) to match silica-rich lamproites. In general, (super S/L) D values are low in potassic-richterites and different partitioning patterns are apparent for REE and LILE. These results are discussed in terms of the distinct crystal-chemical behaviour of the involved amphibole end-members, with particular emphasis on charge-balance mechanisms and site dimensional constraints. It is implied that melts produced from amphibole-bearing sources may differ markedly depending on the type of amphibole crystallized. The role of potassic-richterite in lamproites, peralkaline ultramafic veins in the lithospheric mantle and in deeper parts of subduction zones is discussed.