This project is to continue study of ultramafic xenoliths from the Samoan hotspot chain. Previous work has demonstrated very high noble gas concentrations in the xenoliths, and at least some of them have highly elevated 3He/4He ratios (to 22 RA) and non- atmospheric heavy rare gases. Continued studies of xenoliths from throughout Samoa will provide an important test of the tentative conclusions reached, based on analyses of xenoliths from just two localities. In addition, individual crystals will be analyzed by laser fusion to characterize small-scale noble gas heterogeneity within the xenoliths. To more fully understand the significance of the rare gas results the PIs plan to study the gross chemical composition and the filling pressures of the fluid inclusions in which rare gases reside.
