Introduction: Nakhlites are olivine-bearing clinopyroxene cumulates [e.g., 1]. Based on petrographic characteristics, they may be divided into groups that cooled at different rates and may have been formed at different depths in a single flow [e.g., 2, 3]. The order of cooling rate is Lafayette < Governador Valadares ~ Nakhla < Yamato000593 < NWA817 ~ MIL03346. Nakhlite cumulus pyroxene grains ...

Twenty four samples of xenoliths and country rocks from the 1961 lava flow of Calbuco volcano have been studied. Fourteen samples have been analyzed for major elements and P, Ni, Ba, Cr, V, Zr, Sc, Y, and Sr. Five of these samples were further analyzed for Sm, Nd, Sr, and Pb isotope ratios. Seventeen samples were analyzed under the microscope and three samples were analyzed by microprobe fo...

consumption of '2C-CH4. Such fractionation may occur to dissolve methane transported more slowly through the 7-to 25-cm-thick sedinent cover over-lying the methane production zone via molecular diffusion or to mthane bubbles that become lodged in overyling sulfate-reducing sediments between low-tide bubbling episodes. Gas bubble methane transport in our site accounts for approximately 84% of th...