期刊
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS
卷 115, 期 -, 页码 210-220出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.dsr.2016.06.010
关键词
Authigenic pyrite; Sulfur isotope; Methane seepage; Sulfate-methane transition zone; GMGS2 expedition
类别
资金
- State Key RD Project [2016YFA0601100]
- National Natural Science Foundation of China [41472085, 41172102]
- National Special Project of Gas Hydrate [GZH20110030-50603, GZH20110030-6WX02]
During the last decade, gypsum has been discovered widely in marine methane hydrate-bearing sediments. However, whether this gypsum is an in-situ authigenic precipitate remains controversial. The GMGS2 expedition carried out in 2013 by the Guangzhou Marine Geological Survey (GMGS) in the northern South China Sea provided an excellent opportunity for investigating the formation of authigenic minerals and, in particular, the relationship between gypsum and methane hydrate. In this contribution, we analyzed the morphology and sulfur isotope composition of gypsum and authigenic pyrite as well as the carbon and oxygen isotopic compositions of authigenic carbonate in a drillcore from Site GMGS2-08. These methane-derived carbonates have characteristic carbon and oxygen isotopic compositions (delta C-13: -57.9% to -27.3%. VPDB; delta O-18: +1.0%. to +3.8% VPDB) related to upward seepage of methane following dissociation of underlying methane hydrates since the Late Pleistocene. Our data suggest that gypsum in the sulfate-methane transition zone (SMTZ) of this core precipitated as in-situ authigenic mineral. Based on its sulfur isotopic composition, the gypsum sulfur is a mixture of sulfate derived from seawater and from partial oxidation of authigenic pyrite. Porewater Ca2+ ions for authigenic gypsum were likely generated from carbonate dissolution through acidification produced by oxidation of authigenic pyrite and ion exclusion during methane hydrate formation. This study thus links the formation mechanism of authigenic gypsum with the oxidation of authigenic pyrite and evolution of underlying methane hydrates. These findings suggest that authigenic gypsum may be a useful proxy for recognition of SMTZs and methane hydrate zones in modern and ancient marine methane hydrate geo-systems. (C) 2016 Elsevier Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据