塔里木盆地西南部晚白垩世——早古新世沉积环境演化:来自皮山PBX1井的地化证据  

Late Cretaceous to Early Paleocene sedimentary environment evolution:Geochemical evidences of Well PBX1 in the southwestern Tarim Basin

作　　者：岳勇 蒋恕 田景春[3] 林新[4] YUE Yong;JIANG Shu;TIAN Jingchun;LIN Xin(Shanghai Branch of CNOOC Ltd.,Shanghai 200335,China;Key Laboratory of Tectonics and Petroleum Resources,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;Sedimentary Geology Institute,Chengdu University of Technology,Chengdu 610059,Sichuan,China;Petroleum Exploration&Production Research Institute,SINOPEC Northwest Company,Xinjiang 830011,Urumqi,China)

机构地区：[1]中海石油(中国)有限公司上海分公司研究院,上海200335 [2]中国地质大学武汉构造与油气资源教育部重点实验室,湖北武汉430074 [3]成都理工大学沉积地质研究院,四川成都610059 [4]中国石化西北油田分公司勘探开发研究院,新疆乌鲁木齐830011

出　　处：《中国地质》2024年第2期592-605,共14页Geology in China

基　　金：中国地质调查局项目“雪峰古陆周缘页岩气地质调查”(DD20190558);国家重点研发计划项目课题(2022YFF0801202)联合资助。

摘　　要：【研究目的】白垩纪与古近纪之交发生过地质历史上重大的灾变和异常事件,致使K/Pg界线成为全球最重要的地质界线之一。通过对塔里木盆地晚白垩世—早古新世沉积环境的研究,有助于重建特提斯北部盆地群塔里木盆地的古环境。【研究方法】本文通过塔里木盆地西南部PBX1井岩心的地球化学元素敏感指标研究K/Pg上下环境的变化。【研究结果】晚白垩世晚期古气候属于干热型,早古新世呈现短暂温湿型。古盐度由晚白垩世正常海洋环境向早古新世半咸水、海陆过渡盐湖环境转换,K/Pg界线位置处,古盐度达到最低值。氧化-还原环境由晚白垩世富氧→贫氧的弱氧化-弱还原环境经历了K/Pg事件之后短暂向早古新世富氧环境转化,而后整体上由贫氧的弱氧化-弱还原环境向极贫氧的还原环境演化。【结论】PBX1井地球化学元素敏感指标揭示了中生代—新生代之交灾变异常事件在塔里木盆地响应特征,也是特提斯洋北部盆地群晚白垩世—早古新世沉积环境演化的有效证据。[Objective]The catastrophe and extinctions that occurred in Late Cretaceous is during geological history make the K/Pg boundary become one of the most important geological boundaries in the world.The study of Late Cretaceous-Early Paleocene sedimentary environment evolution of Tarim is helpful to reconstruct the paleogeography in the northern Tethys basins.[Methods]This study employs the sensitivity index analysis of geochemical elements from core samples of Well PBX1 located in the southwestern Tarim Basin to investigate the environment evolution associated with the K/Pg boundary.[Results]The climate was hot and dry in Late Cretaceous and transitioned to a short-term warm and humidity environment in Early Paleocene.The paleo-salinity changed from normal marine environment in Late Cretaceous to brackish water or marine to saline lake in Early Paleocene.The salinity reached minimum at the K/Pg boundary.For redox environment,it experienced the oxic to anoxic environment and weak redox environment in Late Cretaceous to a short-term oxic environment near the boundary to a major anoxic and weak redox environment in Early Paleocene.[Conclusions]The geochemical element sensitivity index of well PBX1 reveals the response characteristics of the catastrophic anomaly event between Cretaceous and Paleocene in the Tarim Basin,which is effective evidence of the of Late Cretaceous-Early Paleocene sedimentary environment evolution in the northern basins of Tethys Ocean.

关 键 词：环境演化 干热型 湿热型 白垩纪—古近纪界线 PBX1井 地质调查工程 塔西南 

分 类 号：P595[天文地球—地球化学]