Labile trace elements in lunar meteorite Yamato-86032

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Contents of siderophile Au, Co and Sb, mobile Ag, Bi, Cd, In, Se, Te, Tl and Zn and lithophile Cs, Ga, Rb and U were determined by RNAA in samples of the lunar meteorite (anorthositic breccia) Yamato (Y)-86032. Contents of the 4 lithophiles in matrix (, 75AM) and anorthositic clast (, 101AC) are similar to those in samples of the other 3 lunar meteorites. This is consistent with all these anorthositic breccias being from the lunar highlands. Contents of the other 11 elements indicate a micrometeorite component of 2.5±1.1% (Cl-equivalent) in the parent regolith of Y-86032,75AM. This value is unusual for lunar samples and is virtually identical to the value for the paired samples Y-82192/3 found in the same bare ice region, suggesting that these 3 specimens derive from the same lunar region in the same impact. No micrometeorite component is detectable in Y-86032,101AC. Slight compositional differences between Y-82192/3 and Y-86032 indicate that they did not travel Earthward as a single rock. Allan Hills-81005 and Y-791197 each exhibit characteristic siderophile/mobile element patterns indicating deviation from different parent regions in separate events. Hence, the 5 lunar meteorites studied thus far derive from 3 distinct impacts.
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