Organic Matter Accumulation in the Upper Permian Dalong Formation from the Lower Yangtze Region,South China  

作　　者：FANG Chaogang ZHANG Chengcheng MENG Guixi XU Jinlong XU Naicen LI Hualing LIU Mu LIU Bo 

机构地区：[1]Institute of International Rivers and Eco-Security,Yunnan University,Kunming 650500,China [2]Nanjing Center,China Geological Survey,Nanjing 210016,China [3]Exploration Research Institute,Anhui Provincial Bureau of Coal Geology,Hefei 230088,China [4]China United Coalbed Methane Corporation Ltd.,Beijing 100015,China [5]Geological Survey of Anhui Province,Hefei 230001,China [6]Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Acta Geologica Sinica(English Edition)》2024年第1期150-167,共18页地质学报（英文版）

基　　金：supported by the Fundamental and Commonwealth Geological Survey of Oil and Gas of China(Grant No.DD 20221662);the National Natural Science Foundation of China(NSFC)Program(Grant No.42302124).

摘　　要：The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.

关 键 词：GEOCHEMISTRY redox condition primary productivity OM accumulation Lopingian/Changhsingian Lower Yangtze region 

分 类 号：P618.13[天文地球—矿床学]