Abstract

Inclusions trapped in olivine of lunar mare and Hawaiian lava lake basalts have yielded data on the following: (1) composition of the melt at the time of olivine crystallization, except for subsequent crystallization of olivine on the walls (from probe analyses on natural or laboratory homogenized glasses); (2) amount and nature of immiscible sulfide melt, and the stage at which it separated (from simple microscopy) (3) equilibrium temperatures and sequence of melting, the nature of the phases other than olivine crystallized within the inclusions during cooling, and a crude measure of the solidus temperature of the trapped fluids (from phase-disappearance heating experiments on crystallized inclusions); (4) relative cooling rates of different flows and some constraints on absolute cooling rates (from simple microscopy and annealing experiments); (5) possible distinctions between phenocrysts and exotic xenocrysts (from the composition of inclusions); (6) presence of a vapor phase at the time of growth of the olivine and some data on its composition (from crushing-stage studies); and (7) minimum pressures at the time of olivine growth (from gas inclusions). Limitations are imposed by the suitability of the available inclusions, by the implicit assumptions, particularly as to the representativeness of the sample, and by the experimental techniques. Not all types of data can be obtained on any given sample, and several important questions and conflicts remain unanswered. In spite of these shortcomings, some of these data are believed to be valid, and some cannot be obtained otherwise.

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