Carbon cycling at a site of present day serpentinization: the tables, Gros Morne National Park

Abstract

This study addresses the origin of methane on Mars. A possible source of methane on Mars has been attributed to serpentinization. Active serpentinization is occurring in the subsurface at The Tablelands Ophiolite, in Gros Morne National Park, Newfoundland. Active serpentinization is evidenced by the highly reducing (Eh~ -700mV), ultra-basic (pH 10-12) groundwater springs containing dissolved methane and other lower molecular weight hydrocarbon gases, and the presence of travertine deposits. -- The source of methane in the springs as determined to be non-microbial and attributed to either thermogenic or possible abiogenic synthesis. Despite this finding, the ultra-basic springs are an extreme environment for an extant microbial community. Phospholipid fatty acid (PLFA) analysis determined an abundance of gram-negative bacteria as well as the presence algae and fungal biomarkers; and carbon isotopic analysis of PLFA suggests both heterotrophic and autotrophic metabolisms.