| Title | Depositional environment and organic matter accumulation of Lower Jurassic nonmarine fine-grained deposits in the Yuanba Area, Sichuan Basin, SW China |
| Authors | Wang, Xinyao Jin, Zhenkui Zhao, Jianhua Zhu, Yixiu Hu, Zongquan Liu, Guangxiang Jiang, Tao Wang, Huan Li, Shuo Shi, Shuting |
| Affiliation | China Univ Petr, State Key Lab Petr Resources & Prospecting, Beijing 102249, Peoples R China China Univ Petr East China, Key Lab Deep Oil & Gas, Qingdao 266580, Peoples R China State Key Lab Shale Oil & Gas Enrichment Mech & E, Beijing 100083, Peoples R China SINOPEC, Key Lab Shale Oil Gas Explorat & Prod, Beijing 100083, Peoples R China SINOPEC, Petr Explorat & Prod Res Inst, Beijing 100083, Peoples R China Peking Univ, Inst Oil & Gas, Beijing 100871, Peoples R China |
| Keywords | MISSISSIPPIAN BARNETT SHALE TIGHT GAS SANDSTONES FORT-WORTH BASIN BLACK SHALES GEOCHEMICAL CHARACTERIZATION SEQUENCE STRATIGRAPHY PETROLEUM GEOLOGY DAANZHAI MEMBER OIL ORIGIN |
| Issue Date | Jun-2020 |
| Publisher | MARINE AND PETROLEUM GEOLOGY |
| Abstract | This study investigated the lithological, sedimentological and geochemical characteristics of Lower Jurassic strata (Ziliujing Formation) in the Sichuan Basin to identify the lithofacies and understand the depositional environments and differences in organic matter accumulation of these nonmarine fine-grained sediments. Based on mineralogy and petrology, rock types were recognized, with mudstones, siltstones, and limestones being the most common. Rock types, sedimentary structures, biota, and well log data were used to define and characterize 17 lithofacies and the following five facies associations of the fine-grained sediments: (1) delta front; (2) clastic lakeshore; (3) clastic shallow lake; (4) clastic semi-deep lake; and (5) carbonate lake. The content of total organic carbon ranges between 0.04% and 3.84%, with an average of 0.74%. The organic matter primarily consists of Type III kerogen. Major processes inferred from the lithofacies analyses include suspension, biogenic, and storm deposition. On the basis of facies associations, redox, climate and salinity conditions, biotic productivity, and terrigenous input, a total of six depositional environments are proposed: (I) high-productivity low-oxygen swamp (II) low-oxygen semi-deep lake (III) high-oxygen semi-deep lake (IV) high-oxygen shallow lake (V) deep-water low-oxygen semi-deep lake and (VI) high-salinity low-oxygen shallow lake. The nonmarine environments changed frequently, unlike more stable environments. The development of bivalves in the shallow lake is suggested to be related to high salinity caused by dry climate, together with limited terrigenous input. Organic-rich nonmarine fine-grained sediments in the Ziliujing Formation formed in swamp and semi-deep lake with settings under reducing conditions, in a humid climate, with relatively high terrigenous input. Results of the study may help us to understand the deposition of nonmarine organic-rich fine-grained Lower Jurassic sediments in southwest, China. |
| URI | http://hdl.handle.net/20.500.11897/588436 |
| ISSN | 0264-8172 |
| DOI | 10.1016/j.marpetgeo.2020.104352 |
| Indexed | SCI(E) Scopus EI |
| Appears in Collections: | 待认领 |
