塔西南坳陷柯东构造带白垩系沉积古环境及沉积特征研究  

Study on Cretaceous sedimentary paleoenvironment and sedimentary characteristics of Kedong tectonic belt in southwestern depression of Tarim Basin

作　　者：孙迪[1] 张立强[2] 黎立[1] 贾彤 屈洋[1] 陈才[1] SUN Di;ZHANG Liqiang;LI Li;JIA Tong;QU Yang;CHEN Cai(Research Institute of Exploration and Development,PetroChina Tarim Oilfield Company,Korla,Xinjiang 841000,China;School of Geoscience,China University of Petroleum,Qingdao,Shandong 266580,China)

机构地区：[1]中国石油塔里木油田分公司勘探开发研究院,新疆库尔勒841000 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《中国科技论文》2024年第7期741-751,共11页China Sciencepaper

基　　金：中国石油塔里木油田分公司科学研究与技术开发项目(041022070101)。

摘　　要：塔西南坳陷柯东构造带白垩系勘探潜力大,但对其沉积演化的认识仍存在争议。基于柯东101井白垩系克孜勒苏群及库克拜组细粒沉积物的微量元素测试结果,结合岩心、露头及测录井资料,讨论了柯东构造带白垩系沉积古环境及沉积演化过程。结果表明:柯东构造带白垩系克孜勒苏群及库克拜组的古气候指标Sr/Cu、Rb/Sr和δEu_(N)的平均值分别为56.37、0.12和1.48,氧化还原指标U/Th、V/Cr、V/(V+Ni)和δCe_(N)的平均值分别为0.29、0.52、0.62和0.86,古盐度指标w(Li)和Sr/Ba平均值分别为26.27μg/g和0.014。微量元素指标指示了干旱、强氧化、低盐度的陆相淡水环境。在克孜勒苏群及库克拜组沉积过程中,干旱强度及盐度自下而上呈现增强的趋势,氧化强度呈减弱趋势。柯东构造带白垩系沉积相纵向上表现为辫状河三角洲-潮坪的演化特征,其中克孜勒苏群及库克拜组整体发育浅水辫状河三角洲沉积,沉积速率整体较快,东巴组演化为海相潮坪沉积;横向上,柯东构造带白垩系自西向东表现为沉积物粒度逐渐降低的变化趋势,相较于研究区东部,西部表现为克孜勒苏群下段辫状河三角洲平原相对发育、库克拜组三角洲前缘砂体厚度较大且粒度相对较粗、东巴组以潮间带更为发育的沉积特征。Despite the great exploration potential of the Cretaceous in Kedong tectonic belt of southwestern depression of Tarim Basin,controversy still exists about the understanding of its sedimentary evolution.In this paper,the sedimentary paleoenvironment and sedimentary evolution of the Cretaceous in Kedong tectonic belt were discussed based on the trace element test results of fine sediments of Kizilsu Group and Kukebai Formation in Kedong 101 Well,as well as the core,outcrop and logging data.The results show that the mean values of paleoclimate indices Sr/Cu,Rb/Sr andδEu_(N) of Kizilsu Group and Kukebai Formation are 56.37,0.12 and 1.48,respectively,and the average values of redox indices U/Th,V/Cr,V/(V+Ni)andδCe_(N) are 0.29,0.52,0.62 and 0.86,respectively.The average values ofω(Li)and Sr/Ba are 26.27μg/g and 0.014,respectively.Trace elements suggest an arid,highly oxidized,and low-salinity terrestrial freshwater environment.During the sedimentation process of the Kizilsu Group and Kukbai Formation,the drought intensity and salinity from bottom to top show an increasing trend,and the oxidation intensity shows a decreasing trend.Sedimentary facies of Cretaceous in Kedong tectonic belt is characterized by the evolution of braided river deltatidal flat,in which the Kizilsu Group and Kukbai Formation develop shallow water braided river delta deposits with a relatively fast sedimentation rate,and the Dongba Formation develops marine tidal flat deposits.Laterally,Cretaceous in Kedong tectonic belt shows a decreasing trend of sediment grain size from west to east.Compared with the eastern region,the braided river delta plain of the lower part of the Kizilsu Group is relatively well developed,the delta front sand body of the Kukebai Formation is thicker and the grain size is relatively coarser,while the intertidal zone of the Dongba Formation is more developed in the western region.

关 键 词：柯东构造带 白垩系 微量元素 古环境 沉积演化 

分 类 号：P595[天文地球—地球化学]