The Mianzhu-Changning rift trough has great potential for the development of the Lower Cambrian source rock. Total organic carbon (TOC), mineral composition, major and trace elements of the Lower Cambrian shales in the central part of the rift trough were measured to reveal the relationship between the tectonic setting, terrigenous input, paleoclimate, primary productivity, redox conditions as well as the hydrothermal activity and the enrichment of organic matter during its development period. The results show that the study area is located in the passive continental margin sedimentary environment, with stable sedimentary rate, warm and humid climate alternated by intermittent climate cooling. The TOC values range from 5.96% to 23.15% with an average content of 11.64%. Nutrient elements of P, Ba, Cu and Ni reveal the high primary productivity during this period, which is due to the increased chemical weathering caused by warm and humid climate, thus importing large amounts of nutrients into the ocean. The index of redox sensitive elements and the content of pyrite indicate that the organic-rich sediments in the second and third stages are mainly developed in the bottom water environment of anaerobic sulfurization. The abnormal enrichment of trace metals may be related to the hydrothermal activity from the seabed under the stretching background in rift during the Early Cambrian, which not only provides material for the flourishing of anaerobic chemoautotrophs, but also facilitates the formation of anaerobic sulfurization environment in the bottom water and promotes the preservation of organic matter after mixing with seawater.
Keywords：Accumulation of organic matter
;
Early Cambrian
;
Inter-platform rift
;
Sichuan Basin
ZHOU Guo-xiao, WEI Guo-qi, HU Guo-yi, WU Sai-jun, TIAN Ya-jie, DONG Cai-yuan. The development setting and the organic matter enrichment of the Lower Cambrian shales from the western rift trough in Sichuan Basin. Natural Gas Geoscience[J], 2020, 31(4): 498-506 doi:10.11764/j.issn.1672-1926.2019.11.013
Fig.2
Sedimentary tectonic setting (a), (b) the triangle map of chemical composition (b) and Ga/Rb Vs. K2O/Al2O3 of the Lower Cambrian shales (revised Separately from Refs.[2], [32] and [29])
Geochemical characteristics, redox conditions, and organic matter accumulation of marine oil shale from the Changliang Mountain area, northern Tibet, China
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Comparative analysis of the siliceous source and organic matter enrichment mechanism of the Upper Ordovician-Lower Silurian shale in the upper-lower Yangtze area
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Submarine-hydrothermal exhalative ore layers in black shales from South China and associated fossils-insights into a Lower Cambrian facies and bio-evolution
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Geochemical characterisation and organic matter enrichment of Upper Cretaceous Gongila shales from Chad (Bornu) Basin, northeastern Nigeria: Bioproductivity versus anoxia conditions
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Investigating the use of sedimentary geochemical proxies for paleoenvironment interpretation of thermally mature organic-rich strata: Examples from the Devonian-Mississippian shales, Western Canadian sedimentary basin
Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian (Missourian) stark shale member of the Dennis Limestone, Wabaunsee County, Kansas, U.S.A
Mineralogical and geochemical anomalies of Late Permian coals from the Fusui Coalfield, Guangxi Province, southern China:Influences of terrigenous materials and hydrothermal fluids
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Sedimentary tectonic setting (a), (b) the triangle map of chemical composition (b) and Ga/Rb Vs. K<sub>2</sub>O/Al<sub>2</sub>O<sub>3</sub> of the Lower Cambrian shales (revised Separately from Refs.[2], [32] and [29])Fig.2
错巴沟剖面下寒武统页岩地球化学特征
Geochemical characteristics of Lower Cambrian shales in the Cuobagou sectionFig.33 讨论
Geochemical characteristics, redox conditions, and organic matter accumulation of marine oil shale from the Changliang Mountain area, northern Tibet, China
Early Cretaceous ferruginous and its control on the lacustrine organic matter accumulation: Constrained by multiple proxies from the Bayingebi Formation in the Bayingebi Basin, Inner Mongolia, NW China
Organic accumulation in the lower Chihsia Formation (Middle Permian) of South China: Constraints from pyrite morphology and multiple geochemical proxies
Comparative analysis of the siliceous source and organic matter enrichment mechanism of the Upper Ordovician-Lower Silurian shale in the upper-lower Yangtze area
Multiple controls on the paleoenvironment of the Early Cambrian marine black shales in the Sichuan Basin, SW China: Geochemical and organic carbon isotopic evidence
Climatic-oceanic forcing on the organic accumulation across the shelf during the Early Cambrian (Age 2 through 3) in the mid-upper Yangtze Block, NE Guizhou, South China
Submarine-hydrothermal exhalative ore layers in black shales from South China and associated fossils-insights into a Lower Cambrian facies and bio-evolution
... 四川盆地早寒武世岩相古地理（a）（据文献[24]修改）和错巴沟剖面(b)Lithofacies palaeogeography of the Sichuan Basin during the Early Cambrian(a)(modified from Ref.[24]) and the Cuobagou section(b)Fig.12 样品与分析方法
本文22个页岩样品采自四川省绵阳市高川乡错巴沟剖面 (31°38′16″ N, 104°10′51″ E)（图1）.为确保取样点能够反映古海洋环境的连续变化规律，取样间隔控制在1 m左右.同时，为保证样品测试结果能够反映其原始信息，在采样之前，需剥离去除取样点约20 cm的风化表层.取样之后，将样品密封保存以防污染. ...
... 四川盆地早寒武世岩相古地理（a）（据文献[24]修改）和错巴沟剖面(b)Lithofacies palaeogeography of the Sichuan Basin during the Early Cambrian(a)(modified from Ref.[24]) and the Cuobagou section(b)Fig.12 样品与分析方法
本文22个页岩样品采自四川省绵阳市高川乡错巴沟剖面 (31°38′16″ N, 104°10′51″ E)（图1）.为确保取样点能够反映古海洋环境的连续变化规律，取样间隔控制在1 m左右.同时，为保证样品测试结果能够反映其原始信息，在采样之前，需剥离去除取样点约20 cm的风化表层.取样之后，将样品密封保存以防污染. ...
Sedimentary tectonic setting (a), (b) the triangle map of chemical composition (b) and Ga/Rb Vs. K<sub>2</sub>O/Al<sub>2</sub>O<sub>3</sub> of the Lower Cambrian shales (revised Separately from Refs.[2], [32] and [29])Fig.2
错巴沟剖面下寒武统页岩地球化学特征
Geochemical characteristics of Lower Cambrian shales in the Cuobagou sectionFig.33 讨论
Geochemical characteristics of the Silurian shales from the central tautides, southern Turkey: Organic matter accumulation, preservation and depositional environment modeling
Sedimentary tectonic setting (a), (b) the triangle map of chemical composition (b) and Ga/Rb Vs. K<sub>2</sub>O/Al<sub>2</sub>O<sub>3</sub> of the Lower Cambrian shales (revised Separately from Refs.[2], [32] and [29])Fig.2
错巴沟剖面下寒武统页岩地球化学特征
Geochemical characteristics of Lower Cambrian shales in the Cuobagou sectionFig.33 讨论
Geochemical characterisation and organic matter enrichment of Upper Cretaceous Gongila shales from Chad (Bornu) Basin, northeastern Nigeria: Bioproductivity versus anoxia conditions
Investigating the use of sedimentary geochemical proxies for paleoenvironment interpretation of thermally mature organic-rich strata: Examples from the Devonian-Mississippian shales, Western Canadian sedimentary basin
Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian (Missourian) stark shale member of the Dennis Limestone, Wabaunsee County, Kansas, U.S.A
Mineralogical and geochemical anomalies of Late Permian coals from the Fusui Coalfield, Guangxi Province, southern China:Influences of terrigenous materials and hydrothermal fluids
Fluctuations in chemical weathering on the Yangtze block during the Ediacaran-Cambrian transition: Implications for paleoclimatic conditions and the marine carbon cycle
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