Trace element partitioning between orthopyroxene and anhydrous silicate melt on the lherzolite solidus from 1.1 to 3.2 GPa and 1,230 to 1,535 °C in the model system Na2O-CaO-MgO-Al2O3-SiO2

Frei D, Liebscher A, Franz G, Wunder B, Klemme S, Blundy JD

Research article (journal)

Abstract

For any numerical modelling of magma genesis, especially to check for crustal contribution to a mantle-derived magma, a thorough knowledge of mineral-melt partition coefficients for different P-T conditions is essential. We determined experimentally the Nernst distribution coefficient between orthopyroxene and anhydrous silicate melt for trace elements i in the system Na2O-CaO-MgO-Al2O3-SiO2 (NCMAS) along the dry model lherzolite solidus from 1.1 GPa/1230oCup to 3.2 GPa/1535°C in a piston cylinder apparatus by analyzing melt and orthopyroxene with a combination of electron microprobe and ion probe analyses. We provide partitioning data for trace elements Li, Be, B, K, Sc, Ti,V, Cr, Co, Ni, Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Ce, Sm, Nd, Yb, Lu, Hf, Ta, Pb, U, and Th. The melts are boniniticat 1.1 and 2.0 GPa, picritic at 2.3 GPa and komatiitic at 2.7 and 3.2 Gpa. Orthopyroxene is tschermakitic with 8mol%Mg-Tschermaks MgAl[AlSiO6] at 1.1. GPa while at higher pressure it has 18-20 mol%. We also determined the intracrystalline distribution on the two different M-sites M1 and M2 in orthopyroxene, and the values for D0, E0, and r0 according to the lattice strain model.

Details zur Publikation

Release year: 2009
Language in which the publication is written: English