Melting Relations of the Allende Meteorite

Abstract

The proportions of major oxides in the Allende carbonaceous chondrite after partial reduction are remarkably similar to those in possible mantle material of the earth. When heated, the Allende meteorite generates a sulfide melt (47 percent iron, 25 percent nickel, and 24 percent sulfur by weight), a ferrobasaltic melt, and olivine with or without pyroxene, over a wide pressure range (5 to 25 kilobars). The silicate melt contains more sodium and less titanium than lunar ferrobasalts. An aggregate of the Allende chondrite rich in calcium and aluminum produces silica-undersaturated, calcium-rich melt and spinel over a wide pressure and temperature range. From these studies, it is suggested that the earth's core contains significant amounts of both nickel and sulfur and that a 3 : 2 mixture of Allende bulk sample and calcium- and aluminum-rich aggregates is closer in major element abundances than either of these components to the average composition of the moon.