<p>Uranium-thorium isotope systematics of cold-seep carbonate and their constraints on geological methane leakage activities</p>

doi:10.1016/j.gca.2021.12.016

	Uranium-thorium isotope systematics of cold-seep carbonate and their constraints on geological methane leakage activities
	Wang, Maoyu 1,2; Chen, Tianyu 1,2,3; Feng, Dong 4; Zhang, Xin 3; Li, Tao 1,2; Robinson, Laura F.5; Liang, Qianyong 6; Bialik, Or M.7; Liu, Yuanyuan 1,2; Makovsky, Yizhaq 8,9
	2022-03-01
发表期刊	GEOCHIMICA ET COSMOCHIMICA ACTA
ISSN	0016-7037
卷号	320 页码:105-121
通讯作者	Chen, Tianyu(tianyuchen@nju.edu.cn)
摘要	Marine methane hydrates are a huge and dynamic carbon reservoir found mainly at the continental margins, and their stability might be affected by climate-associated pressure and temperature changes on the seafloor. Reconstructing the growth history of cold-seep carbonates, which formed during seafloor methane leakage, could help to constrain methane hydrate stability in the geological past. However, U-Th isotope systematics of these complex carbonate cements have not yet been system-atically investigated on the micro-scale, leaving uncertainties in the U-series geochronology which is commonly applied to date the seep carbonates. In this study, we have developed multiple in-situ analytical methods, including U-Th isotope analysis by laser ablation MC-ICPMS, elemental concentration mapping by laser ablation ICPMS, as well as organic distribution mapping by Raman Spectroscopy, to provide insights into the U-series geochemistry and geochronology for the different types of cold-seep carbonates. Our result demonstrates that U-238 and Th-232 of these carbonates are dominantly derived from seawater and detrital particles, respectively. As the [Th-230/Th-232] (activity ratio) of micro-domains with high [Th-232/U-238] is negligibly affected by U decay, we have directly determined the initial [Th-230/Th-232] of the cold-seep carbonates which is 0.7 +/- 0.1 (2 SD, n = 12). In general, U-series isotopes show closed-system behavior within our studied analytical precision in the interior of the seep cements, and the initial [Th-230/Th-232] derived from the isochron approach is consistent with the in-situ direct determination. A notable exception is a calcitic pipe sample with highly enriched U in its rim which has also experienced post-depositional mobilization. Our method is then applied to a large set of seep carbonate samples from the upper continental slope of the northern South China Sea (SCS). The obtained U-series ages provide evidence that cold seep was likely continuously active since at least ~72 ka in the northern SCS, but the timing and duration of methane leakage vary between different sites within this region. While the upper continental slope methane hydrates are highly susceptible to destabilization under changing bottom water conditions, our extensive dating on seep carbonates from the SCS further indicates that bottom water P-T conditions could exert contrasting impacts on methane hydrate stability at different depths within the same geological setting. Overall, the in-situ U-series geochronological method developed in our study has the potential to date cold-seep carbonates efficiently and reliably, offering new opportunities to probe into the history of methane leakage in the late Quaternary. (C)& nbsp;2021 Elsevier Ltd. All rights reserved.
关键词	Cold-seep carbonate Element mapping U-Th dating Methane leakage duration
DOI	10.1016/j.gca.2021.12.016
收录类别	SCI
语种	英语
资助项目	National Natural Science Foundation of China[41822603] ; National Natural Science Foundation of China[41991325] ; National Natural Science Foundation of China[42021001] ; Guangdong Basic and Applied Basic Research Foundation[2019B030302004] ; China Geological Survey[DD20190218] ; CAS Interdisciplinary Innovation Team[JCTD-2018-12]
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000786623000004
出版者	PERGAMON-ELSEVIER SCIENCE LTD
引用统计	被引频次：9[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/178862
专题	深海极端环境与生命过程研究中心
通讯作者	Chen, Tianyu
作者单位	1.Nanjing Univ, Sch Earth Sci, State Key Lab Mineral Deposits Res, Nanjing 210023, Peoples R China 2.Nanjing Univ, Engn & Frontiers Sci Ctr Crit Earth Mat Cycling, Nanjing 210023, Peoples R China 3.Chinese Acad Sci, Inst Oceanol, Ctr Deep Sea Res, Ctr Ocean Mega Sci, Qingdao 266071, Peoples R China 4.Shanghai Ocean Univ, Coll Marine Sci, Shanghai Engn Res Ctr Hadal Sci & Technol, Shanghai 201306, Peoples R China 5.Univ Bristol, Sch Earth Sci, Bristol BS8 1RJ, Avon, England 6.China Geol Survey, Guangzhou Marine Geol Survey, MLR Key Lab Marine Mineral Resources, Guangzhou 510070, Peoples R China 7.Univ Malta, Dept Geosci, Marine Geol & Seafloor Surveying, Msida, MSD, Malta 8.Univ Haifa, Leon H Charney Sch Marine Sci CSMS, Dr Moses Strauss Dept Marine Geosci, IL-31905 Haifa, Israel 9.Univ Haifa, Leon H Charney Sch Marine Sci CSMS, Hatter Dept Marine Technol, IL-31905 Haifa, Israel
通讯作者单位	深海极端环境与生命过程研究中心
推荐引用方式 GB/T 7714	Wang, Maoyu,Chen, Tianyu,Feng, Dong,et al. Uranium-thorium isotope systematics of cold-seep carbonate and their constraints on geological methane leakage activities [J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2022,320:105-121.
APA	Wang, Maoyu.,Chen, Tianyu.,Feng, Dong.,Zhang, Xin.,Li, Tao.,...&Makovsky, Yizhaq.(2022). Uranium-thorium isotope systematics of cold-seep carbonate and their constraints on geological methane leakage activities .GEOCHIMICA ET COSMOCHIMICA ACTA,320,105-121.
MLA	Wang, Maoyu,et al." Uranium-thorium isotope systematics of cold-seep carbonate and their constraints on geological methane leakage activities ".GEOCHIMICA ET COSMOCHIMICA ACTA 320(2022):105-121.

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