Limestone petrography and geochemical composition at ROV station GeoB12353-11

Authigenic carbonate build-ups develop at seafloor methane-seeps, where microbially mediated sulphate-dependent anaerobic oxidation of methane facilitates carbonate precipitation. Despite being valuable recorders of past methane seepage events, their role as archives of atmospheric processes has not been examined. Here we show that cyclic sedimentation pulses related to the Indian monsoon in concert with authigenic precipitation of methane-derived aragonite gave rise to a well-laminated carbonate build-up within the oxygen minimum zone off Pakistan (northern Arabian Sea). U?Th dating indicates that the build-up grew during past ~1,130 years, creating an exceptional high-resolution archive of the Indian monsoon system. Monsoon-controlled formation of seep-carbonates extends the known environmental processes recorded by seep-carbonates, revealing a new relationship between atmospheric and seafloor processes.

自生碳酸盐建隆（authigenic carbonate build-ups）发育于海底甲烷渗漏区，在此区域内，微生物介导的硫酸盐依赖型甲烷厌氧氧化作用可促进碳酸盐沉淀。尽管这类建隆是记录古甲烷渗漏事件的珍贵载体，但其作为大气过程档案的研究价值尚未得到系统考察。本研究表明，与印度季风相关的周期性沉积脉动与甲烷成因文石的自生沉淀共同作用，在巴基斯坦外海（阿拉伯海北部）的氧最低带（oxygen minimum zone）内形成了一处纹层发育完好的碳酸盐建隆。铀钍测年（U-Th dating）结果显示，该建隆在过去约1130年间持续发育，构建了一套分辨率极高的印度季风系统专属档案。受季风调控的渗漏碳酸盐岩（seep-carbonates）形成作用拓展了渗漏碳酸盐岩所记录的已知环境过程范畴，揭示了大气过程与海底过程之间的全新关联。