气候变化领域集成服务门户(CCPortal): Sm-Nd isochron dating and geochemical (rare earth elements, 87Sr/86Sr, δ18O, δ13C) characterization of calcite veins in the Jiaoshiba shale gas field, China: Implications for the mechanisms of vein formation in shale gas systems

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DOI	10.1130/B32015.1
	Sm-Nd isochron dating and geochemical (rare earth elements, 87Sr/86Sr, δ18O, δ13C) characterization of calcite veins in the Jiaoshiba shale gas field, China: Implications for the mechanisms of vein formation in shale gas systems
	Gao J.; He S.; Zhao J.-X.; He Z.; Wu C.; Feng Y.; Nguyen A.D.; Zhou J.; Yi Z.
发表日期	2020
ISSN	167606
起始页码	1722
结束页码	1740
卷号	132 期号:2021-07-08
英文摘要	The Wufeng and Longmaxi organic-rich shales host the largest shale gas plays in China. This study examined the petrography, rare earth element (REE) and other trace-element geochemistry, Sm-Nd geochronology, and isotope geochemistry (87Sr/86Sr, δ18O, δ13C) of fracture-cementing minerals within core samples of the Wufeng and Longmaxi Formations from the Jiaoshiba shale gas field in order to (1) characterize the mineral phases occurring in the veins (mineralized fractures); (2) determine the ages of the calcite by the Sm-Nd isochron dating method; (3) understand the sources of calcite-precipitating fluids; and (4) explore the possible mechanisms responsible for calcite vein formation in shale gas systems. The fractures hosted in the Longmaxi Formation are mineralized with quartz as the predominant fracture cement, and calcite as an intracementation phase postdating the earlier quartz cement. In contrast, the fractures hosted in the Wufeng Formation are dominantly mineralized by calcite, which occurs either as the only cement present or as a cement phase predating later quartz cement. Calcite veins within the Longmaxi Formation have a Sm-Nd isochron age of 160 ± 13 Ma and δ13C values of-4.71‰ to-3.11‰, δ18O values of 17.1‰-17.4‰, and 87Sr/86Sr values of 0.72437-0.72869. Calcite veins within the Wufeng Formation yielded a Sm-Nd isochron age of 133 ± 15 Ma and are characterized by δ13C values of-2.29‰ to-1.03‰, δ18O values of 17.3‰-17.7‰, and 87Sr/86Sr values of 0.72202-0.72648. The similarity between 87Sr/86Sr values of the calcite and those of their respective surrounding host rocks (0.72670-0.72875 of the Longmaxi shales; 0.72030-0.72648 of the Wufeng shales), combined with relatively depleted δ13C and uniform fluid δ18O isotopic features, indicates that the calcite-precipitating fluids within the Wufeng and Longmaxi Formations were derived largely from their respective surrounding host-rock sources. REE data equally indicate that the distinguishable Eu anomalies (6.20-19.35; 4.45-11.91), Y anomalies (1.03-1.50; 1.44-1.70), and Y/Ho ratios (28.80-39.16; 38.86-45.18) of calcite veins within the Longmaxi and Wufeng Formations were controlled by their respective surrounding host rocks. The Sm-Nd isochron ages and fluid inclusion data of fracture cements suggest that fracture opening and calcite precipitation in composite veins within the Wufeng and Longmaxi Formations were triggered by gas generation overpressurization. © 2019 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184760
作者单位	Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Wuhan, 430074, China; Petroleum Exploration and Production Research Institute, SINOPEC, Beijing, 100083, China; School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia; School of Resource Environment and Earth Sciences, Yunnan University, Kunming, 650504, China
推荐引用方式 GB/T 7714	Gao J.,He S.,Zhao J.-X.,et al. Sm-Nd isochron dating and geochemical (rare earth elements, 87Sr/86Sr, δ18O, δ13C) characterization of calcite veins in the Jiaoshiba shale gas field, China: Implications for the mechanisms of vein formation in shale gas systems[J],2020,132(2021-07-08).
APA	Gao J..,He S..,Zhao J.-X..,He Z..,Wu C..,...&Yi Z..(2020).Sm-Nd isochron dating and geochemical (rare earth elements, 87Sr/86Sr, δ18O, δ13C) characterization of calcite veins in the Jiaoshiba shale gas field, China: Implications for the mechanisms of vein formation in shale gas systems.Bulletin of the Geological Society of America,132(2021-07-08).
MLA	Gao J.,et al."Sm-Nd isochron dating and geochemical (rare earth elements, 87Sr/86Sr, δ18O, δ13C) characterization of calcite veins in the Jiaoshiba shale gas field, China: Implications for the mechanisms of vein formation in shale gas systems".Bulletin of the Geological Society of America 132.2021-07-08(2020).