北羌塘胜利河地区布曲组优质烃源岩形成环境与有机质富集机制  

Formation environment and organic matter enrichment mechanism of high-quality source rocks in the Buqu Formation in the Shenglihe area,northern Qiangtang basin

作　　者：陈程 吴珍汉[4] 赵为永 王利[6] 季长军[4] 赵珍[4] 张浩 龚赞 CHEN Cheng;WU Zhenhan;ZHAO Weiyong;WANG Li*;JI Changjun;ZHAO Zhen;ZHANG Hao;GONG Zan(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Paleomagnetism and Tectonic Reconstruction,Ministry of Natural Resources,Beijing 100081,China;Key Laboratory of Petroleum Geomechanics,China Geological Survey,Beijing 100081,China;Chinese Academy of Geological Sciences,Beijing 100037,China;Exploration and Development Research Institute,Qinghai Oilfield Branch,PetroChina,Dunhuang,Gansu 736202,China;China Geological Survey,Beijing 100037,China;Nanjing Geological Survey Center,China Geological Survey,Nanjing,Jiangsu 210016,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]自然资源部古地磁与古构造重建重点实验室,北京100081 [3]中国地质调查局油气地质力学重点实验室,北京100081 [4]中国地质科学院,北京100037 [5]中国石油青海油田分公司勘探开发研究院,甘肃敦煌736202 [6]中国地质调查局,北京100037 [7]中国地质调查局南京地质调查中心,江苏南京210016

出　　处：《地质学报》2024年第2期530-543,共14页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号42102201);中国地质调查项目(编号DD20221660-2)联合资助的成果。

摘　　要：羌塘盆地是我国陆上新区油气勘探程度最低的中生代海相含油气沉积盆地,其主力烃源岩一直认识不清。本文以胜利河地区中侏罗统布曲组烃源岩为研究对象,开展了有机地球化学和元素地球化学的系统研究,探讨了布曲组烃源岩的形成环境和有机质富集机制,为预测北羌塘坳陷中侏罗统布曲组优质烃源岩的分布提供了理论依据。胜利河地区布曲组烃源岩有机质丰度高,有机质类型为Ⅱ型,处于成熟阶段,综合评价为优质烃源岩。布曲组沉积时期,气候干旱炎热,研究区初级生产力水平较高,属于弱局限盆地,具有浅水、高盐度、贫氧—缺氧的沉积环境。布曲组沉积时期,羌塘盆地发生大规模海侵,研究区邻近中央隆起,陆源输入和热液活动携带大量营养物质磷、铁等进入海洋,导致较高的初级生产力,是北羌塘坳陷布曲组优质烃源岩有机质富集的主控因素。研究区位于北羌塘坳陷的最小含氧带区域,有利于大量浮游生物在此缺氧死亡埋藏保存。通过有机质富集机制的分析,北羌塘坳陷的近岸陆棚斜坡带可能是中侏罗统布曲组优质烃源岩分布的有利区域。The Qiangtang basin is the Mesozoic marine sedimentary basin with the lowest degree of oil and gas exploration in the new land area,and its main source rocks have not been clearly understood.In this paper,the organic geochemistry and element geochemistry of the source rocks of the Middle Jurassic Buqu Formation in Shenglhe area have been systematically studied,and the formation environment and organic matter enrichment mechanism of the source rocks of the Buqu Formation have been discussed.This provides a theoretical basis for predicting the distribution of high-quality source rocks in the Middle Jurassic Buqu Formation in the North Qiangtang depression.The source rocks of the Buqu Formation in Shenglihe area have high abundance of typeⅡof organic matter in mature stage.During the Buqu period,the climate was arid and hot,and the primary productivity level of the study area was relatively high,which was a weakly confined basin with shallow water,high salinity and oxygen-poor depositional environment.During the Buqu period,large-scale transgression occurred in the Qiangtang basin,and the study area was adjacent to the central uplift.A large number of nutrients such as phosphorus and iron from terrigenous input and hydrothermal activities were carried into the ocean,resulting in higher primary productivity,which was the main controlling factor for the enrichment of organic matter in high-quality source rocks of the Buqu Formation in the North Qiangtang depression.The study area is located in the minimum oxygen-containing zone of the North Qiangtang depression,which is conducive to the anoxic death and burial of a large number of planktons.Through the analysis of organic matter enrichment mechanism,the coastal shelf slope zone of the North Qiangtang depression may be a favorable area for the distribution of high-quality source rocks in the Middle Jurassic Buqu Formation.

关 键 词：有机质富集 优质烃源岩 古生产力 胜利河 北羌塘坳陷 

分 类 号：P618.13[天文地球—矿床学]