Upwelling current and its relationship to the enrichment of organic matter in the Lower Silurian Longmaxi Formation,northern Chongqing-western Hubei area,southern China  

作　　者：Jun-Jun Shen Jia-Kai Yan Peng-Wan Wang Yu-Man Wang Lin Zhou Yu-Bing Ji Min Xu 

机构地区：[1]Hubei Cooperative Innovation Center of Unconventional Oil and Gas of Yangtze University,Wuhan 430100,Hubei Province,China [2]Hydrogeology and Engineering Geology Institute of Hubei Geological Bureau,Jingzhou 434020,Hubei Province,China [3]PetroChina Hangzhou Institute of Petroleum Geology,Hangzhou 310023,Zhejiang Province,China [4]PetroChina Research Institute of Petroleum Exploration and Development,Bejing 100083,China [5]Exploration and Production Research Institute,Jianghan Oifield Company,SINOPEC,Wuhan 430100,Hubei Province,China [6]Zhejiang Oilfield Company Integrated Center of Exploration and Development,Hangzhou 310000,Zhejiang Province,China

出　　处：《Journal of Palaeogeography》2024年第4期993-1015,共23页古地理学报（英文版）

基　　金：supported by the Hubei Province Natural Science Geological Innovation Development Joint Funding Project (2024AFD388)。

摘　　要：Upwelling currents play a crucial role in the enrichment of organic matter,yet the mechanisms driving this process remain incompletely understood due to methodological and data resolution limitations.In this paper,we employ a combination of biostratigraphic classification,qualitative methods,and quantitative methods to systematically analyze the sedimentological and geochemical characteristics of the Lower Silurian Longmaxi Formation in the northern Chongqing-western Hubei area,southern China.The relationship between the upwelling currents and organic matter enrichment in the shale of the Longmaxi Formation is investigated.Results indicate that the upwelling currents in the study area were primarily influenced by the foreland flexure process.From the Rhuddanian(flexure-sedimentation stage)to the Aeronian(flexure-migration stage),the more intense tectonic activity led to gradual opening of the barrier between the South Qinling Ocean and the Yangtze Platform,resulting in an increase in the influx of the oceanic current.The upwelling currents significantly contributed to the organic matter production,albeit without substantially affecting the preservation conditions.Throughout the succession of the Longmaxi Formation,the organic matter content decreased gradually from the passive continental margin to the foreland flexural stagnant basin,which was mainly due to deterioration of the preservation conditions as a result of sea level fall and increased terrigenous input.Despite the increase in the upwelling currents,they did not decisively control the organic matter enrichment.Spatially,during the Rhuddanian to Aeronian period,the organic matter content decreased similarly from the passive continental margin to the foreland flexural stagnant basin,influenced by reduced organic matter production caused by weakening of the upwelling currents and the worsening preservation conditions caused by sea-level fall.The terrigenous input had a relatively minor impact.The results of this study provide new insights into the role of

关 键 词：Middle-Upper Yangtze Ordovician-Silurian transition Black shale Passive continental margin Foreland flexural stagnant basin Sedimentary paleoenvironment 

分 类 号：P618.13[天文地球—矿床学]