Calcite U-Pb dating and geochemical constraints on fracture opening in organic-rich shales
文献类型：期刊论文
| 作者 | Liu, Dadong1,6; Tian, Hui5; Jia, Chengzao1,4; Fan, Qingqing1,6; Lu, Xuesong3; Xu, Mingyang1,6; Song, Yan1,6; Zhang, Chen2 |
| 刊名 | INTERNATIONAL JOURNAL OF COAL GEOLOGY
 |
| 出版日期 | 2024-11-11 |
| 卷号 | 294页码:13 |
| 关键词 | Fluid overpressure calcite U - Pb dating C -O-Sr isotopes natural fracture shale gas |
| ISSN号 | 0166-5162 |
| DOI | 10.1016/j.coal.2024.104621 |
| 英文摘要 | Gas-bearing, organic-rich shales commonly host numerous opening-mode fractures; however, their formation mechanism remains controversial, with competing arguments of tectonic-origin and/or hydrocarbon generation pressurization-origin. Here, we studied fracture fillings in shale reservoirs of the lower Silurian Longmaxi Formation in the Luzhou area, southern Sichuan Basin, SW China. Using in-situ U-Pb geochronology, rare earth elements (REEs) and C-O-Sr isotope geochemistry, and fluid inclusion analyses, we investigated the timing and geochemical attributions of fracture fills and identify the mechanism of fracture formation. The results show that, the cements that occupy fractures in the Longmaxi Formation shales contain mainly calcite and quartz. The calcite cements show crack-seal and fibrous textures, indicating that they are syn-kinematic mineral deposits. The 87Sr/86Sr values of the calcite cements essentially overlap with those of their proximal host shales. This result, combined with slight depletions in delta 13CPDB and relatively uniform fluid delta 18OSMOW isotopic features, indicate that the fluids from which the calcite precipitated were largely derived from their surrounding host shales. Abundant methane inclusions are present in fracture cements, with trapping pressures of 104.5-157.5 MPa and pressure coefficients of 1.92-2.43, suggesting they were trapped in an overpressurized fluid system. In-situ U-Pb dating of calcite cements yielded ages of ca. 160 Ma and ca. 110 Ma, which coincide with the timing of thermal cracking of oil to gas during burial. In combination with the overpressurized, geochemically closed fluid system, the fractures were most likely triggered by gas generation. Our study emphasizes that natural fracturing induced by hydrocarbon generation overpressurization is an essential mode of brittle failure in tectonically quiescent basins worldwide. |
| WOS研究方向 | Energy & Fuels ; Geology |
| 语种 | 英语 |
| WOS记录号 | WOS:001340066200001 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/81267]  |
| 专题 | 有机地球化学国家重点实验室 |
| 通讯作者 | Liu, Dadong; Tian, Hui; Zhang, Chen |
| 作者单位 | 1.China Univ Petr, State Key Lab Petr Resources & Engn, Beijing 102249, Peoples R China 2.Chengdu Univ Technol, State Key Lab Oil & Gas Reservoir Geol & Exploitat, Chengdu 610059, Peoples R China 3.PetroChina, Res Inst Petr Explorat & Dev, Beijing 100083, Peoples R China 4.China Natl Petr Corp, Beijing 100724, Peoples R China 5.Chinese Acad Sci, State Key Lab Organ Geochem, Guangzhou Inst Geochem, Guangzhou 510640, Peoples R China 6.China Univ Petr, Unconvent Petr Res Inst, Beijing 102249, Peoples R China |
| 推荐引用方式 GB/T 7714 | Liu, Dadong,Tian, Hui,Jia, Chengzao,et al. Calcite U-Pb dating and geochemical constraints on fracture opening in organic-rich shales[J]. INTERNATIONAL JOURNAL OF COAL GEOLOGY,2024,294:13. |
| APA | Liu, Dadong.,Tian, Hui.,Jia, Chengzao.,Fan, Qingqing.,Lu, Xuesong.,...&Zhang, Chen.(2024).Calcite U-Pb dating and geochemical constraints on fracture opening in organic-rich shales.INTERNATIONAL JOURNAL OF COAL GEOLOGY,294,13. |
| MLA | Liu, Dadong,et al."Calcite U-Pb dating and geochemical constraints on fracture opening in organic-rich shales".INTERNATIONAL JOURNAL OF COAL GEOLOGY 294(2024):13. |
入库方式： OAI收割
来源：广州地球化学研究所
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