HIGH-TEMPERATURE DENSITIES OF SOME MANTLE MELTS

One-atmosphere density measurements at very high temperatures have bee n performed on four mantle melts in the FeO-Fe2O3-CaO-MgO-Al2O3-SiO2 s ystem (FeO-rich peridotite, PHN 1611, komatiite, and fayalite), using the Lr-based double-bob Archimedean method in air. The one-atmosphere density of the investigated materials ranges from 2.6 to 3.6 g/cm(3) f rom their respective melting points up to 2123 K. Combined with earlie r high-pressure static experiments on the same compositions, the prese nt one-atmosphere densities provide robust constraints on the isotherm al compression curves of such Fe-bearing silicate melts and yield new values of the isothermal bulk modulus (K-T) and its pressure derivativ e (K-T') through application of the third order Birch-Murnaghan equati on of state. The present K-T and K-T' values are significantly differe nt from those previously reported using the high-pressure dataset toge ther with calculated one-atmosphere densities using existing schemes. Comparisons with K-T-K-T' systematics from the literature are also mad e. Copyright (C) 1997 Elsevier Science Ltd.