柴达木盆地路乐河剖面磁性地层年代及其构造变形  

Magnetostratigraphy of the Cenozoic Lulehe section in the Qaidam Basin:Implications for the tectonic deformation on the northeastern Tibetan Plateau

作　　者：段磊 张博譞 王伟涛 张培震 唐清 陈干 贾佳宝 闫永刚 黄荣 郑文俊 Lei Duan;Boxuan Zhang;Weitao Wang;Peizhen Zhang;Qing Tang;Gan Chen;Jiabao Jia;Yonggang Yan;Rong Huang;Wenjun Zheng(School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,China)

机构地区：[1]中山大学地球科学与工程学院,广州510275 [2]南方海洋科学与工程广东省实验室(珠海),珠海519082

出　　处：《科学通报》2022年第9期872-887,共16页Chinese Science Bulletin

基　　金：第二次青藏高原综合科学考察研究(2019QZKK0901);国家自然科学基金(42030301,41872204,41580861)资助。

摘　　要：青藏高原东北缘的柴达木盆地发育巨厚的新生代地层.这些地层记录了印度与欧亚大陆碰撞以来青藏高原向东北方向扩展过程中的构造变形、地貌演化与气候变化等信息.通过高密度的样品采集、测试与分析,古地磁测年结果显示,柴达木盆地北缘新生代地层出露较为连续、完整的路乐河剖面(路乐河组层型剖面)沉积年龄为30.9~5.2 Ma.路乐河剖面沉积环境与沉积速率分析揭示盆地新生代以来经历了约31与15 Ma开始的两期显著的构造变形事件:渐新世的构造变形导致了柴达木盆地的形成;中中新世以来的强烈构造变形导致了柴达木盆地的变形与改造.The Qaidam Basin is the largest Cenozoic basin located on the northeastern margin of the Tibetan Plateau.The extremely thick Cenozoic sedimentary strata in the basin recorded regional tectonic deformation and associated climate change when the Tibetan Plateau grew outward to its margins.The Cenozoic strata in the Qaidam Basin have been historically subdivided into seven primary stratigraphic units:The Lulehe,Xia Ganchaigou,Shang Ganchaigou,Xia Youshashan,Shang Youshashan,Shizigou,and Qigequan formations.Although many studies have been performed in recent decades,the Qaidam Basin’s inception,development and extinction are still unclear,which requires more work,such as highresolution magnetostratigraphies.This paper focuses on the Lulehe section,which is the type section of the Lulehe Formation on the northern margin of the Qaidam Basin.The Lulehe section encompasses the Lulehe to Shizigou Formations,and the section was previously estimated to have been initially deposited 52 Ma.We collected paleomagnetic samples from 2041 sites in the Lulehe section to establish magnetic polarity sequences of the section.Constrained by the regional stratigraphic correlation,the recognized magnetic polarity sequences of the Lulehe section were anchored to chrons C12 n–C3 n.4 n(31–5 Ma).Our correlation places the age of the Lulehe Formation at 30.9–23.7 Ma,suggesting that the onset of sediment accumulation in the Qaidam Basin occurred ca.31 Ma.Overlying the Lulehe Formation,the Xia Ganchaigou Formation was deposited from 23.7 to18.1 Ma,the Shang Ganchaigou Formation spans from 18.1 to 12.9 Ma,the Xia Youshashan Formation spans from 12.9 to 9.9 Ma,the Shang Youshashan Formation spans from 9.9 to 6.9 Ma,and Shizigou Formation is younger than6.9 Ma.To characterize the sedimentary environments of strata within the Lulehe section,we undertook a detailed stratigraphic analysis.At the bottom of the section,the Lulehe Formation is characterized by alluvial facies(30.9–23 Ma).Upward,the Xia Ganchaigou Formation and Shang Ganchaigou

关 键 词：柴达木盆地 磁性地层 路乐河剖面 构造变形 

分 类 号：P548[天文地球—构造地质学] P539.3[天文地球—地质学]