| Experiments on phase equilibria and trace element partitioning in natural materials are important constraints on understanding magma evolution. This study is divided into three sections: (1) the phase equilibria of Cr-spinel in oceanic basalt, (2) variation of the pyroxene-melt partition coefficients for Zr, Nb and Ta, and (3) variations in ;In the first part, spinel synthesis experiments on Ocean Drilling Program Leg 135 samples suggest that the spinels from Hole 839B must have crystallized above 1200;In the second section, composition and temperature controls on pyroxene-melt partitioning for Ti, Zr, Nb, and Ta are evaluated from doped experiments on natural lavas at pressures from 0.1 MPa to 0.9 GPa. D values decrease from ;Zr-, Nb-, and Ta-doped experiments yield ilmenite-melt partition coefficients in the final part of this study ranging from mildly incompatible to compatible (... |
