Pore Water Geochemistry and Quantification of Methane Cycling

Abstract

AbstractOwing to numerous scientific cruises in the past two decades, pore water data from more than 250 sites within gas hydrate and cold seep areas of the South China Sea have been reported. These investigated sites are mainly distributed in the Dongsha–Taixinan, Shenhu, and Qiongdongnan areas of the northern South China Sea, together with a few sites from the Beikang Basin of the southern South China Sea. Pore water geochemical profiles at these sites have been used to indicate fluid sources that are linked to gas hydrates and methane seepage, to distinguish the anaerobic oxidation of methane (AOM) from organoclastic sulfate reduction, to reveal fluid flow patterns, and to quantify the rates of AOM. As the pore water data accumulate over a broad area of the SCS, recent attempts have been made to quantify regional sulfate and methane cycling in the subseafloor of the northern South China Sea. This quantitative assessment on a regional scale highlights the importance of deep-sourced methane in governing subseafloor carbon and sulfur cycling along continental margins.