大陆碰撞过程中山脉形成和高原生长的核心机制是固体地球科学的研究前沿，目前争论主要在楔形挤出和隧道流两种模型中。喜马拉雅核部高级变质岩系（高喜马拉雅）的两种不同形式折返过程（“顺序式”向南扩展和“脉冲隧道式”），是该问题的重要研究内容。本项目拟对珠峰地区的高喜马拉雅进行研究，克服退变质岩石P-T-t-D轨迹重建存在的诸多难点，甄别其具体折返形式，解决上述争论。具体拟开展以下研究内容：1）运用EBSD技术测量应变和变形温度间断来识别构造-变质不连续带；2）在寻找峰期矿物包裹体、用XMapTools软件计算峰期矿物成分和有效全岩成分基础上，运用相平衡模拟手段重建压力峰期温压条件和P-T轨迹；3）通过精细的“岩石年代学”研究来区分各个阶段的变质年龄，限定峰期变质时代和部分熔融持续时间。本项目有望为P-T-t-D轨迹重建的难点提供新的研究思路，为高喜马拉雅的折返过程和大陆碰撞造山机制提供关键制约。

One of the research frontiers in solid earth-science is the mechanism for mountain belt formation and plateau growth during continental collision, and the main controversy lies between wedge extrusion and channel flow models. A key content related to this controversy is the two different exhumation processes of high-grade metamorphic rock series in the Himalayan core (GHC, “In-sequence” propagating toward south versus “Plused channel flow”). This study aims to distinguish the different exhumation processes and solve the controversy through overcoming the existing difficulties of recovering P-T-t-D paths of retrogressed metamorphic rocks in the GHC, Mount Everest region. The following researches are going to be carried out: 1) Tectono-metamorphic discontinuities will be recognized by strain measurement and break of deformation temperatures using EBSD technique; 2) P-T conditions of the pressure-peak and P-T paths will be recovered by phase equilibrium modelling using the effective bulk composition calculated by XMapTools software, combined with observed or recovered mineral compositions of the pressure-peak; 3) Timing of the pressure-peak and duration of partial melting will be recovered by sophisticated “Petrochronology” study, which can distinguish timing of different metamorphic stages. Overall, this study is potential to provide new research approaches to overcome the difficulties in recovering P-T-t-D paths and put key constraints on the multi-exhumation processes of the GHC and orogenic mechanisms during continental collision.