Lherzolitic Martian meteorites Allan Hills 77005, Lewis Cliff 88516 and Yamato-793605: Major and minor element zoning in pyroxene and plagioclase glass

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Three lherzolitic Martian meteorites (ALH77005,LEW88516 and Y-793605) show very similar petrography and mineralogy. They consist of the poikilitic and non-poikilitic (interstitial) areas that are heterogeneous on a cm-scale. A detailed electron microprobe analysis of pyroxene and plagioclase glass from these meteorites gives characteristic distributions of major and minor elements. It is striking that pyroxene and plagioclase glass in all three meteorites have nearly identical zoning patterns of these elements, while olivine shows different chemistry. This is because olivine chemistry was largely controlled by a late-stage re-equilibration which did not significantly modify the major and minor element distributions in pyroxene and plagioclase glass. However, a close look at minor element zoning in plagioclase glass exhibits slightly different zoning patterns among these three meteorites, corresponding to different degrees of re-equilibration (degrees of re-equilibration : ALH77005>LEW88516>Y-793605). Nevertheless, it is evident that they experienced a very similar igneous crystallization history and they are likely to have originated from the same igneous unit on Mars.
国立極地研究所の論文