Chemical and isotopic compositions of methane and carbon dioxide in hydrothermal fluids from the Mariana Trough

Abstract

We clarify the chemical and isotopic compositions of methane and carbon dioxide in hydrothermal fluids from the Mariana Trough. On Pika site, carbon isotope ratio of methane in the sample is lighter than the supposed mixing line between hydrothermal fluids and seawater. On Fryer site, that is heavier than the mixing line. These results suggest that the methane is affected by microbial activity. On Archaean site, the isotope ratio is lighter than the samples from the other sites, suggesting equilibrium reacion of carbon isotope was quenching at lower temperature.