Helium and Carbon Isotopes in 2005-06 EPR Basalts

Abstract: Helium and carbon isotope compositions, and He and CO2 concentrations were measured in the vesicles of basalt glasses from the 1991-1992 and 2005-2006 eruptions at the RIDGE 2000 Integrated Study Site on the East Pacific Rise near 9°50’N. The sampling of the recent eruptions at the ISS offered a unique opportunity to study magma recharge along the mid-ocean ridge, to quantify the amount of degassing that occurred prior to and during eruption, and ultimately to evaluate the extent to which mantle carbon is incorporated into hydrothermal fluids and ultimately into seafloor ecosystems. The selected samples cover all stages of the 2005-2006 eruption as discerned from the 210Po-210Pb dating by K Rubin (U Hawaii), and also cover the spatial extent of what was collected via submersible and dredging. The same lava samples have been characterized by P Michael (U Tulsa) for vesicle abundances and size distributions, and for dissolved CO2 and H2O concentrations by FTIR.