The PIs will measure He, Ne, Ar, Kr, and Xe isotopes, rare gas concentrations, visicle size distributions and C/3He ratios in glassy basalts from four regions of the mid-ocean ridge system. Well preserved, glassy basalts will be analyzed by stepwise heating and in vacuo crushing techniques. The isotopic compositions and abundances of rare gases, in conjunction with other chemical parameters will provide insight into magma transport and volatile injection at ridge crests, and into the origins and scales of the components contributing to mantle heterogeneity and to the petrogenesis of oceanic crust.
