鄂尔多斯盆地三叠系延长组长10-长8段沉积演化特征  

Evolution characteristics of Ordos Basin in sedimentary period of Chang 10-Chang 8 member of Yanchang Formation

作　　者：邓秀芹[1] 庞锦莲[1] 孙勃[1] DENG Xiuqin;PANG Jinlian;SUN Bo(Exploration and Development Research Institution of Changqing Oilfield Company/National Engineering Laboratory for Exploration and Development of Low-Permeability Oil&Gas Fields,Xi’an 710018,China)

机构地区：[1]低渗透油气田勘探开发国家工程实验室/中国石油长庆油田分公司勘探开发研究院,陕西西安710018

出　　处：《西北大学学报（自然科学版）》2024年第6期1078-1090,共13页Journal of Northwest University（Natural Science Edition）

基　　金：国家科技重大专项(2017ZX05001)。

摘　　要：通过分析鄂尔多斯盆地延长组长10—长8段沉积期地层发育特征、碎屑充填结构变化、沉积相展布,并结合岩石学、元素地球化学分析,提出受秦岭造山作用的影响,长10—长8段沉积期为鄂尔多斯盆地强烈沉降成盆期、台-盆发展转换期、气候环境转折期:①明确长10段沉积期发生了显著的沉降作用,沉降中心位于盆地西南环县—镇原—正宁一带,不对称性显著,粗碎屑快速充填,厚度巨大,长9段、长8段沉积期是构造平稳阶段气候控制为主的沉积,沉积物粒度相对较细;②提出长10期沉降作用结束了晚古生代稳定的地台性质的沉积,开始了内陆盆地演化阶段,在碎屑沉积物的成熟度、供屑原岩特征等方面均留下了造山带构造活动影响下的台-盆转化与盆地演化的示踪信息;③长10段沉积期结束了晚二叠世以来长期的干旱炎热的气候,经历了半干旱、半潮湿向温暖湿润气候转变;④长10—长8段构成了延长组下部沉降-充填旋回,该旋回在沉降中心厚1000~1550 m,具有粗碎屑快速充填、颗粒向上变细的特点。本研究深化了鄂尔多斯盆地形成、演化的认识。By analyzing the stratigraphic development characteristics,clastic filling structure and sedimentary facies distribution of the Chang 10-Chang 8 sedimentary period of the Yanchang Formation in the Ordos Basin,combined with petrological and geochemical analysis,it is proposed that affected by the Qinling orogeny,Ordos Basin strongly subsided,transformed from platform to basin,and climate shifted sharply at the Chang 10-Chang 8 sedimentary period:①It is cheared that significant subsidence occurred during the sedimentary period of the Chang 10,and the subsidence center is located in Huanxian-Zhenyuan-Zhenning area,the southwestern basin,with significant asymmetry rapidly filled by thick coarse clastic.Chang 9 and Chang 8 member are stable deposits dominated by climate in a stable tectonic environment,with relatively fine sediment.②It is proposed that the Chang 10 subsidence ended the stable platform during the late Paleozoic and began the evolution of inland basin.The platform-basin transformation and basin evolution under the influence of orogenic tectonic activities have left traces in the maturity of clastic sediments and the characteristics of detrital protoliths.③The sedimentary period of Chang 10 member ended the long-term arid and hot climate since the Late Permian,and began the transition to semi-arid and semi-humid,and to warm and humid climate.④The Chang 10-Chang 8 members constitute a subsidence-filling cycle of lower Yanchang Formation,about 1000~1550 m thick in the subsidence center.This study furthers the understanding of the formation and evolution of the Ordos Basin.

关 键 词：长10—长8段 长10沉降作用 台-盆转化 气候转折 鄂尔多斯盆地演化 

分 类 号：P512.2[天文地球—地质学]