Environmental controls on sulfur isotopic compositions of sulfide minerals in seep carbonates from the South China Sea

doi:10.1016/j.jseaes.2018.04.037

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	Environmental controls on sulfur isotopic compositions of sulfide minerals in seep carbonates from the South China Sea
	Peng, Yongbo 5; Tong, Hongpeng 5; Gong, Shanggui 4; Hu, Yu 5; Li, Niu ; Feng, Dong 1; Liang, Qianyong 3; Chen, Duofu 1,5; Tao, Jun 5
刊名	JOURNAL OF ASIAN EARTH SCIENCES
	2018
卷号	168 页码:96
关键词	Authigenic carbonate andpyrite Sulfur isotope Fluid intensity Cold seep South China Sea
ISSN号	1367-9120
DOI	10.1016/j.jseaes.2018.04.037
英文摘要	Authigenic carbonates and pyrite associated with sulfate-driven anaerobic oxidation of methane (AOM) at methane seeps provide archives to explore the biogeochemical processes involved and seepage dynamics over time. The wide range and extremely high delta S-34 values of pyrite (delta S-34(py)) have been used to trace the AOM-related processes. However, the detailed mechanism for this phenomenon is not well understood. We propose that the characteristics of delta S-34(py) were mainly controlled by the competition between sulfate reduction and sulfate supply, as well as the redox condition. To test this hypothesis, we investigated Sr/Ca and Mg/Ca ratios, trace element compositions, pyrite contents and sulfur isotopic compositions in seep carbonates from Site F and Haima in the northern South China Sea. Calcite and aragonite contents were distinguished through the Sr/Ca and Mg/Ca ratios. The data show that aragonites are always associated with relatively low delta S-34(py) values compared to calcites. The Mo contents show a good correlation with pyrite contents in calcites and aragonites, and the slope in aragonites is larger than that in calcites. This relationship indicates that the aragonite precipitated in a relatively open system with higher Mo availability. Thus, we conclude that sulfides with low delta S-34 values formed at high supply of sulfate under the relatively open system with respect to diffusive replenishment of sulfate, where the carbonate precipitation occurred close to the seafloor due to a strong methane flux. Under vigorous methane flux simultaneously, the high potential of less anoxic conditions, which could limit the additional pyrite accumulation and/or favor the microbial disproportionation, could also be the cause of the low delta S-34(py), as supported by samples from the Haima sites. Evidence for this assumption is based on the occurrence of bivalve shells and less enrichment in As and Sb. Conversely, the positive delta S-34(py) values result from near to complete exhaustion of dissolve sulfate via AOM within a deeper sulfate-methane transition zone, where Mo is less available. The combination of a detailed elemental study of authigenic carbonates with sulfur isotopic composition of sulfide minerals in carbonates is a promising tool for reconstructing the dynamics of seep intensities at modern and, potentially, geological seep sites.
内容类型	期刊论文
源URL	[http://ir.scsio.ac.cn/handle/344004/17666]
专题	南海海洋研究所_中科院边缘海地质重点实验室
作者单位	1.Chinese Acad Sci, CAS Key Lab Ocean & Marginal Sea Geol, South China Sea Inst Oceanol, Guangzhou 510301, Guangdong, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.Shanghai Ocean Univ, Coll Marine Sci, Shanghai Engn Res Ctr Hadal Sci & Technol, Shanghai 201306, Peoples R China 4.China Geol Survey, MLR Key Lab Marine Mineral Resources, Guangzhou Marine Geol Survey, Guangzhou 510070, Guangdong, Peoples R China 5.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao 266237, Peoples R China
推荐引用方式 GB/T 7714	Peng, Yongbo,Tong, Hongpeng,Gong, Shanggui,et al. Environmental controls on sulfur isotopic compositions of sulfide minerals in seep carbonates from the South China Sea[J]. JOURNAL OF ASIAN EARTH SCIENCES,2018,168:96, 105.
APA	Peng, Yongbo.,Tong, Hongpeng.,Gong, Shanggui.,Hu, Yu.,Li, Niu.,...&Tao, Jun.(2018).Environmental controls on sulfur isotopic compositions of sulfide minerals in seep carbonates from the South China Sea.JOURNAL OF ASIAN EARTH SCIENCES,168,96.
MLA	Peng, Yongbo,et al."Environmental controls on sulfur isotopic compositions of sulfide minerals in seep carbonates from the South China Sea".JOURNAL OF ASIAN EARTH SCIENCES 168(2018):96.