早中寒武世古环境特征与烃源岩发育模式——以塔里木盆地柯坪-巴楚地区为例  

Paleoenvironmental characteristics and source rock development model of the Early-Middle Cambrian:A case of the Keping-Bachu area in the Tarim Basin

作　　者：欧阳思琪 吕修祥[1,2] 薛楠 李峰[1,2] 汪瑞 OUYANG Siqi;LYU Xiuxiang;XUE Nan;LI Feng;WANG Rui(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)地球科学学院,北京102249

出　　处：《中国矿业大学学报》2022年第2期293-310,共18页Journal of China University of Mining & Technology

基　　金：国家油气重大专项(2017ZX05005002)。

摘　　要：为了更全面的认识塔里木盆地中下寒武不同层位烃源岩的发育模式,本文以柯坪-巴楚地区为例,在沉积演化研究的基础上,利用有机碳、主微量元素以及碳同位素的测量数据,分析了研究区早中寒武世古环境特征,建立了各时期烃源岩的发育模式.认为沉积相、古地貌、热液活动、海平面变化、上升洋流共同影响了研究区古生产力与氧化-还原环境,进而控制了烃源岩中有机质的富集模式.研究结果表明:柯坪地区玉尔吐斯组与肖尔布拉克组烃源岩发育于海侵体系域中-外缓坡相,玉尔吐斯期伴有上升洋流与热液活动,热液活动强度自下而上逐渐减弱,于玉_(中)段停止;TOC,V/(V+Ni),U/Th,过剩钡(Ba_(xs))等指标指示从玉^(1)_(下)亚段到肖^(1)_(下)亚段与肖^(2)_(下)亚段有机质丰度、古生产力水平与沉积水体的缺氧程度均呈先升高后降低的特征,玉^(2)_(下)亚段沉积期达到最高(TOC平均值为5.21%,V/(V+Ni)平均值为0.98,U/Th平均值为10.08,Ba_(xs)平均值为95221×10^(-6));巴楚地区肖尔布拉克组-阿瓦塔格组烃源岩发育于干热古气候背景下的台内潟湖相,肖_(上)段与吾松格尔组沉积期潟湖水体较深,蒸发旋回初期为缺氧时期,发育碳酸盐岩烃源岩.柯坪地区玉^(1)_(下)亚段、玉^(2)_(下)亚段、玉_(中)段泥页岩烃源岩发育模式分别为海侵伴有强热液与上升洋流模式、海侵伴有弱热液与上升洋流模式、海侵伴有上升洋流模式;肖^(1)_(下)亚段与肖^(2)_(下)亚段碳酸盐岩烃源岩为海侵发育模式.海侵与上升洋流是柯坪地区烃源岩发育的基础,热液活动对有机质聚集的影响具有两面性.巴楚地区肖尔布拉组与吾松格尔组烃源岩为台内潟湖蒸发分层发育模式,古地貌与海平面变化是影响烃源岩发育的关键.In order to have a more comprehensive understanding of development patterns of the Middle-Lower Cambrian source rocks in Tarim Basin,we used the method of TOC,major elements,trace elements,and carbon isotopes to test the samples from Keping-Bachu area.Based on the research on sedimentary evolution,the Early-Middle Cambrian paleoenvironmental characteristics of the study area were analyzed,and the development model of the source rock in each period was established.It is indicated that sedimentary facies,paleogeomorphology,hydrothermal activity,sea-level change,and upwelling affect the paleoproductivity and redox environment of the study area,thus controlling the source rock development model and organic matter abundance.The results show that the source rocks of the Yuertus formation and Xiaoerbulak formation in the Keping area are developed in the middle-outer ramp of the transgressive system.During the deposition period of Yuertus,there are upwelling and hydrothermal activity.The intensity of hydrothermal activity gradually weakened from bottom to top in the lower part of Yuertus formation and stopped in the middle part of Yuertus formation.TOC,V/(V+Ni),U/Th,excess Ba(Ba_(xs))and other indicators indicate that the organic matter abundance,paleoproductivity,and anoxic degree of sedimentary water first increased and then decreased from the first member of lower part of Yuertus formation to the first member and the second member of lower part of Xiaoerbulak.The highest part was the second member of lower part of Yuertus formation(the average of TOC is 5.21%,the average of V/(V+Ni)is 0.98,the average of U/Th is 10.08,and the average of Ba_(xs) is 95221×10^(-6)).The source rocks from Xiaoerbulak formation to Awatag formation in Bachu area developed in the intra platform lagoon in the background of dry and hot paleoclimate.The lagoon in the sedimentary period of the upper Xiaoerbulak formation and Wusonger formation was deep.In the early stage of the evaporation cycle,source rocks developed in the anoxic environment.T

关 键 词：古环境 烃源岩发育模式 柯坪-巴楚地区 中下寒武统 塔里木盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]