Organic matter enrichment model of fine-grained rocks in volcanic rift lacustrine basin:A case study of lower submember of second member of Lower Cretaceous Shahezi Formation in Lishu rift depression of Songliao Basin,NE China  

作　　者：XIE Huanyu JIANG Zaixing WANG Li XUE Xinyu 

机构地区：[1]School of Energy Resources,China University of Geosciences,Beijing 100083,China [2]China National Offshore Oil Limited Corporation-Zhanjiang,Zhanjiang 524057,China [3]School of Marine Sciences,Sun Yat-sen University,Zhuhai 519082,China

出　　处：《Petroleum Exploration and Development》2024年第5期1232-1246,共15页石油勘探与开发（英文版）

基　　金：Supported by the National Science and Technology Major Project of China(2017ZX05009-002);National Natural Science Foundation of China(41772090)。

摘　　要：Based on sedimentary characteristics of the fine-grained rocks of the lower submember of second member of the Lower Cretaceous Shahezi Formation(K_(1)sh_(2)^(L))in the Lishu rift depression,combined with methods of organic petrology,analysis of major and trace elements as well as biological marker compound,the enrichment conditions and enrichment model of organic matter in the fine-grained sedimentary rocks in volcanic rift lacustrine basin are investigated.The change of sedimentary paleoenvironment controls the vertical distribution of different lithofacies types in the K_(1)sh_(2)^(L)and divides it into the upper and lower parts.The lower part contains massive siliceous mudstone with bioclast-bearing siliceous mudstone,whereas the upper part is mostly composed of laminated siliceous shale and laminated fine-grained mixed shale.The kerogen types of organic matter in the lower and upper parts are typesⅡ_(2)–Ⅲand typesⅠ–Ⅱ_(1),respectively.The organic carbon content in the upper part is higher than that in the lower part generally.The enrichment of organic matter in volcanic rift lacustrine basin is subjected to three favorable conditions.First,continuous enhancement of rifting is the direct factor increasing the paleo-water depth,and the rise of base level leads to the expansion of deep-water mudstone/shale deposition range.Second,relatively strong underwater volcanic eruption and rifting are simultaneous,and such event can provide a lot of nutrients for the lake basin,which is conducive to the bloom of algae,resulting in higher productivity of typesⅠ–Ⅱ_(1)kerogen.Third,the relatively dry paleoclimate leads to a decrease in input of fresh water and terrestrial materials,including TypeⅢkerogen from terrestrial higher plants,resulting in a water body with higher salinity and anoxic stratification,which is more favorable for preservation of organic matter.The organic matter enrichment model of fine-grained sedimentary rocks of volcanic rift lacustrine basin is established,which is of reference sig

关 键 词：fine-grained sedimentary rocks organic matter sources RIFTING volcanic activity Lower Cretaceous Shahezi Formation Lishu rift depression Songliao Basin 

分 类 号：P618.13[天文地球—矿床学] TE34[天文地球—地质学]