The geobiological formation process of the marine source rocks in the Middle Permian Chihsia Formation of South China  

作　　者：LIU XiTing YAN JiaXin XUE WuQiang MA ZhiXin LI Bo 

机构地区：[1]Faculty of Earth Sciences and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences [2]MARUM-Center for Marine Environmental Sciences, University of Bremen [3]Chengdu Institute of Geology and Mineral Resources [4]Guangzhou Marine Geological Survey

出　　处：《Science China Earth Sciences》2014年第5期957-964,共8页中国科学（地球科学英文版）

基　　金：supported by National Basic Research Program of China (Grant No. 2011CB808800);National Natural Science Foundation of China (Grant No. 41072078)

摘　　要：The Chihsia Formation is one of the four sets of regional marine hydrocarbon source rocks from South China.In the past two decades,detailed geochemical and sedimentological studies have been carried out to investigate its origination,which have demonstrated that the high primary productivity plays a primary role in the deposition of sediments enriched in the organic matter.However,the mechanism of this high productivity and the path of the deposition and burial of the organic matter have always been a mystery.Based on the previous studies on the Shangsi Section in Guangyuan City,Sichuan Province,we proposed that the development of the equatorial upwelling due to the sea level rise is responsible for the relatively high productivity in the Chihsia Formation.The sea waters with high nutrient were transported by the sub-surface currents along the equator.High organic carbon flux was deposited on the deeper shelf,and then decomposed by bacteria,leading to the occurrence of anaerobic respiration.The metabolism of the microorganisms consumed the dissolved oxygen in waters,which was in favor of the preservation of the organic matter.This suggested geobiological model integrating with paleoclimatology,paleoceanography and geomicrobiology will help us to understand the causes of this particular sedimentary sequence.The Chihsia Formation is one of the four sets of regional marine hydrocarbon source rocks from South China. In the past two decades, detailed geochemical and sedimentological studies have been carried out to investigate its origination, which have demonstrated that the high primary productivity plays a primary role in the deposition of sediments enriched in the organic matter. However, the mechanism of this high productivity and the path of the deposition and burial of the organic matter have always been a mystery. Based on the previous studies on the Shangsi Section in Guangyuan City, Sichuan Province, we pro- posed that the development of the equatorial upwelling due to the sea level rise is responsible for the relatively high productiv- ity in the Chihsia Formation. The sea waters with high nutrient were transported by the sub-surface currents along the equator. High organic carbon flux was deposited on the deeper shelf, and then decomposed by bacteria, leading to the occurrence of anaerobic respiration. The metabolism of the microorganisms consumed the dissolved oxygen in waters, which was in favor of the preservation of the organic matter. This suggested geobiological model integrating with paleoclimatology, paleoceanogra- phy and geomicrobiology will help us to understand the causes of this particular sedimentary sequence.

关 键 词：Chihsia Formation source rocks primary productivity paleo-oxygenation facies GEOBIOLOGY South China 

分 类 号：P736[天文地球—海洋地质]