平衡剖面方法恢复柴达木盆地新生代地层缩短及其意义  

Cenozoic deformation history determined by restoration of the balanced section across the Qaidam Basin

作　　者：刘栋梁[1] 方小敏[1] 王亚东[1] 张伟林[1] 高军平[2] 

机构地区：[1]中国科学院青藏高原研究所盆地与资源环境研究中心,北京100085 [2]兰州大学资源环境学院西部环境教育部重点实验室,兰州730000

出　　处：《地质科学》2008年第4期637-647,共11页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金委重点基金项目(批准号:40334038);中国科学院重要创新方向性项目(kzcx2-yw-104);国家教育部重点项目(306016)联合资助

摘　　要：柴达木盆地为一中-新生代盆地,位于青藏高原北缘,盆内中-新生代地层发育,很好地记录了印度板块与欧亚板块自距今55Ma以来碰撞传播到高原北缘的地质事件。本文以最新的高精度磁性地层和年代地层为约束,通过盆地内部一条北东—南西向地震大剖面,用平衡剖面方法恢复新生代以来盆地因两大板块碰撞而引起的北东—南西向地壳缩短量,揭示盆地的性质和变形历史。结果表明:柴达木盆地在印度板块与欧亚板块碰撞的早期就开始变形,呈现弱的挤压状态,至始新世中-晚期变形明显增强,然后略为减弱,从中新世中-晚期尤其更新世以来地壳缩短速率快速增加,反映此时挤压变形最强烈,高原北部快速隆升。The Qaidam Basin,located in the northern margin of the Qinghai-Tibetan Plateau,was a large Mesozoic-Cenozoic basin and deposited huge thick continuous Cenozoic strata,which recorded well the geological events of collision between the India and Eurasian plates since - 55Ma. Based on latest new progress in high resolution dating of the magnetostratigraphy, a technique of balanced section across the whole basin was applied to a NE-SW seismic-geological profile in the central Qaidam Basin to reconstruct the crust shortening history from collision and to understand the nature of the basin. The results showed that the Qaidam Basin began to deform nearly synchronous to the early collision, manifesting as a weak compression; the deformation increased significantly in the Middle and Late Eocene, and then weakened slightly,and began to accelerate rapidly from the Late Miocene, especially since the Pleistocene, implying the maximal shortening of the basin and rapid uplift of the northern Tibetan Plateau during that time.

关 键 词：平衡剖面 缩短变形 沉积速率 新生代 柴达木盆地 

分 类 号：P542[天文地球—构造地质学]