Trace element distributions in Yamato 793605, a chip off the "martian lherzolite" block.

In situ ion microprobe analyses of various phases in Yamato-793605 (Y79) confirm that it is very similar to the other two lherzolitic shergottites, ALHA77005 and LEW88516. Differences in absolute REE abundances between bulk samples of these meteorites can be largely accounted for by sample heterogeneity. The three lherzolites were formed by essentially identical processes and they may even have originated from the same lithological unit on Mars. Preservation of major element zonation in olivines of Y79 indicates that it is less equilibrated than the other lherzolitic shergottites, and may have crystallized at shallower depth. The parent magmas of lherzolitic shergottites, like those of other shergottites, were derived by partial melting of a partly depleted martian mantle.