The Yamato-793605 martian meteorite consortium

We describe the consortium that has been organized to coordinate study of the Yamato-793605 shergottitic peridotite, a 16-g meteorite of presumed martian origin. Y-793605 is similar to two other Antarctic martian meteorites, ALH-77005 and LEW88516. One of the most important goals of the consortium is to determine how the cosmic-ray exposure history of Y-793605 compares with those of ALH-77005 and LEW88516. An aphanitic-glassy shock melted lithology that constitutes, as scattered veins and globby enclaves, roughly 30 vol% of the rock, has also been targeted for particularly intense scrutiny. Consortium results reported in the papers that follow confirm strong similarities between Y-793605 and ALH-77005 and LEW88516,in terms of mineralogy and petrology, trace elements, and cosmic-ray exposure. The mineralogical, petrological, and trace-element similarities are so strong, they suggest that Y-793605,ALH-77005 and LEW88516 formed as cumulates (i.e., mainly large poikilitic pyroxenes enclosing cumulus olivines and chromites) from a single parent magma. The igneous crystallization age of Y-793605 has not yet been precisely determined. However, some important consortium investigations are still underway