帕米尔和西南天山碰撞对接过程的古地磁记录

This project will focus on the relative integrated natural Cenozoic sections in the Southwest Tarim Basin from two-side systems of Pamir and Southwestern Tian Shan. On the basis of detail researches of paleomagnetism (magnetostratigraphy and rock-magnetism) and terrestrial cosmogenic nuclides (TCNs, Al-Be-Ne), we want to obtain the integrated Cenozoic magnetostratigraphy in the mountain front of the two different systems and the paleomagnetic evidences of the basin records for deciphering the two systems collision. The paleomagnetic researches include Cenozoic sedimentation rate, magnetic susceptibility, magnetic minerals, palaeostress field or paleocurrent direction, etc. Combining with this project and previous paleomagnetism, sedimentological records in the basin and low temperature thermochronology results in the ranges, we want to gain the Cenozoic initial collision time and collision process between Pamir and Southwestern Tian Shan. We also want to rebuild the evolution history between Pamir and Southwestern Tian Shan. The project is expected to make a breakthrough in the collision between Pamir and Southwestern Tian Shan, and it also provides basic geological support to Cenozoic regional climate change, energy resource reconstruction, earthquake prevention and disaster reduction.

本申请拟以塔西南地区的帕米尔和西南天山两大体系较完整的新生代天然剖面为研究对象，采用古地磁（磁性地层和岩石磁学等）和宇宙核素（Al-Be-Ne）埋藏年龄等方法，获得两大体系较完整的新生代磁性地层年代序列和两大体系碰撞对接的盆地沉积记录之古地磁证据（沉积速率、磁化率、磁性矿物、古应力场或古水流方向等），综合前人已发表的古地磁、盆地沉积学、山脉隆升低温热年代学等研究成果，探讨帕米尔和西南天山两大体系的新生代碰撞起始时间和对接过程，重塑帕米尔-西南天山地区的新生代构造演化历史。本申请有望在帕米尔和西南天山碰撞对接取得突破，为该地区新生代气候变化、能源-资源改造和防震减灾等提供基础地质支撑。

帕米尔和西南天山碰撞对接研究对该地区新生代气候变化、能源-资源改造和防震减灾等具有重要意义。本顶目选择塔西南地区的帕米尔和西南天山两大体系较完整的新生代天然剖面为研究对象，获得两大体系较完整的新生代磁性地层年代序列和两大体系碰撞对接的盆地沉积记录之古地磁证据（沉积速率、磁化率、磁性矿物、古应力场或古水流方向等），同时开展“盆山耦合”研究获得两大体系的碰撞对接记录。古地磁初步分析结果显示在中中新世起两大体系开始碰撞对接。“盆山耦合”分析表明西昆仑存在三期新生代构造隆升，分别对应晚始新世（~40-30 Ma）、渐新世（~26 Ma）和中中新世（~15 Ma），且存在北向生长过程，其中中新世为两大体系碰撞对接的起始时间。