天文驱动下的中始新世东营凹陷气候水文演化与有机质富集机理  

Astronomically forced climate-hydrological evolution and organic matter accumulation of Middle Eocene lake record in the Dongying Depression

作　　者：马义权 施玲娜 刘惠民[4] 陆永潮[5] 张晨 马超[1,2,3] MA Yiquan;SHI Lingna;LIU Huimin;LU Yongchao;ZHANG Chen;MA Chao(Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources,Chengdu University of Technology,Chengdu 610059,Sichuan;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,Sichuan;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,Sichuan;SINOPEC Shengli Oilfield Company,Dongying,257001,Shandong;College of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,Hubei)

机构地区：[1]成都理工大学自然资源部深时地理环境重建与应用重点实验室,四川成都610059 [2]成都理工大学油气藏地质及开发工程全国重点实验室,四川成都610059 [3]成都理工大学沉积地质研究院,四川成都610059 [4]中国石油化工股份有限公司胜利油田分公司,山东东营257001 [5]中国地质大学(武汉)资源学院,湖北武汉430074

出　　处：《第四纪研究》2023年第6期1630-1642,共13页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42172181);四川省自然科学基金项目(批准号:2022NSFSC1075);四川省天然气成藏物质基础青年科技创新团队基金项目(批准号:2022JDTD0004)共同资助。

摘　　要：中始新世是古近纪温室气候到冰室气候的重要过渡期,对该时期气候演化的认识主要来自海相沉积记录,而来自陆相沉积记录的证据相对较少,因此探索该时期陆相气候特征和演化规律具有重要意义。渤海湾盆地东营凹陷始新统沙河街组的沙四段-沙三段富有机质页岩层系不仅是我国东部陆相页岩油勘探的重点层段,而且为系统研究中始新世陆相气候演化提供了详实的地质记录。本研究以东营凹陷N1井中始新统(沙四下亚段顶部-沙四上亚段-沙三下亚段下部)厚度约253 m的富有机质页岩层系为分析对象,利用伽马(GR)测井曲线,结合沉积速率定量估计的相关系数法(COCO),开展旋回地层学研究,建立了天文年代标尺。在此基础上,进一步综合Ca和Ti含量、Fe/Al比值以及TOC含量数据,探讨天文驱动力对中始新世东营凹陷气候水文演化和有机质富集的控制作用。结果表明,N1井研究目的层段的沉积年龄为45.06 Ma至40.45 Ma,记录的沙四上亚段延续时间为2.76 Ma,与具有良好年代框架的东营凹陷FY1井的分析结果一致。通过建立偏心率周期与高频层序的对应关系,以GR时间序列的405 ka长偏心率周期作为四级层序的参考曲线,以约100 ka短偏心率周期作为五级层序的参考曲线,将研究目的层段划分出11个四级层序和45个五级层序。研究结果显示,在约41.6 Ma之前,TOC含量、Ca含量和Fe/Al比值时间序列的405 ka周期与Ti含量时间序列和La2010d的405 ka周期呈反相关系;在约41.6 Ma之后,TOC含量、Ca含量和Fe/Al比值时间序列的405 ka周期与Ti含量时间序列的405 ka周期依然是反相关系,但与La2010d的405 ka周期转为正相关系。这说明在约41.6 Ma前后,长偏心率周期影响下的东营凹陷的陆源输入、古生产力、氧化还原条件以及有机质富集机理具有显著差异,这可能与天文驱动力和该时期区域气候变化(总体由干旱转为潮湿)The Middle Eocene is an important period that climate shifts in a stepwise manner from the Early Paleogene greenhouse into the Late Paleogene icehouse world.The current understanding of climate change in the Middle Eocene mainly based on the marine sedimentary records,while there are few studies on the terrestrial sedimentary records and a lack of a consistent high-resolution chronological framework,which has led to a limited understanding of the characteristics and patterns of the terrestrial climatic evolution in this period.The Middle Eocene organic-rich shale succession in the fourth Member to third Member of the Shahejie Formation in the Dongying Depression(Shandong Province,China)is not only a key interval for lacustrine shale oil exploration in Eastern China,but also provides a detailed geological record for the systematic study of the terrestrial climate evolution in the Middle Eocene.In this paper,the Middle Eocene organic-rich shale succession with a thickness of about 253 m and a depositional age of roughly 45~40 Ma of well N1(the top part of the lower fourth Member to lower part of the lower third Member of the Shahejie Formation),which located in the sag area of the Dongying Depression,is taken as the object of the study.Using the GR series(sampling rate of 0.125 m),combined with the correlation coefficient method(COCO)for quantitative estimation of sedimentation rate,we carried out a cyclostratigraphic study and established an astronomical time scale for the study interval.The established age model is applied to Ca,Fe,and Ti content,Fe/Al ratio,and TOC content data,and by correlating their 405 ka cycles with the long eccentricity cycle of La2010d,we analysis the control effects of the long eccentricity on the terrestrial inputs,paleoproductivity,and redox conditions in the Dongying Depression during Middle Eocene,and explore the process of astronomical forcing on the climatic and hydrological evolution and the organic matter accumulation in the study area.The results show that the GR series of well

关 键 词：始新世 沙河街组 页岩油 旋回地层 古气候 有机质富集 

分 类 号：P534.613[天文地球—古生物学与地层学] P539.2[天文地球—地质学] P512.6