Abstract

In order to accelerate the gravitational settling and floating of crystals in silicate liquids at high temperatures we have built a furnace which operates at 1200 °C while being rotated in a centrifuge at 2200 RPM. The heating element is constructed of Kanthal wire wound around a 14.5 mm ID mullite tube and the temperature is controlled and measured by two Pt–10 Rh thermocouples. The power and thermocouple circuits are connected, through a slip-ring assembly mounted on the centrifuge shaft, to a temperature controller and potentiometer.The rotation of the furnace and experimental charges produces a gravitational force 700 times that of earth gravity (g). This increases the settling and floating rates for crystals or immiscible liquids by a factor of 700 over the rates at 1 g. A 1-h run in the centrifuge is thus dynamically equivalent to a 1-mo run at 1 g. Preliminary experiments with basaltic liquids containing olivine, pyroxene, plagioclase, and magnetite crystals are described.

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