东喜马拉雅构造结垂向高程剖面热年代学研究

The argument that surface denudation controlled by outside dynamical factor can induce crust tectonic activity in compressive orogenic belt, has been a hot issue of earth system sciences. Due to the multiple solutions of field evidence, this argument is still controversial. Because of its unique advantages such as high level differences, strong glacier activities, intense fluvial incision, fast rock exhumation and so on, the Namche Barwa Peak area in the eastern Himalayan syntaxis is an ideal location in which to investigate this argument. Our latest research result of this area has preliminary demonstrated this argument, using the nonuniform of rock exhumation fields in different crust depths. On the basis of this research result, the proposal intend to analyze a vertical section of this region, using variety thermochronology methods, and quantitatively interpret the thermochronological data, uncover the complete rock exhumation fields in different crust depths. The proposal also intend to contrastively analyze the rock exhumation fields and the surface denudation intensity, find the interrelation of the two, and determine either the surface denudation or the tectonic activity induces the crust exhumation of this area. Finally, the proposal will effectively prove the argument that surface denudation induce tectonic activities, and establish a model of active orogenic belts’ geological evolution dominated by outside dynamical factor.

地球外动力因素主导的地表剥蚀作用，在挤压造山带环境下能够诱发地壳构造活动这一观点，是当今地球系统科学的热点问题。由于野外证据的多解性，该观点目前仍存在较大争议。东喜马拉雅构造结南迦巴瓦峰区域因海拔高差大、冰川活跃、河流强烈下切以及地壳隆升快等独特优势，成为检验这一观点的理想区域和热点地区。近年申请人在该区域获得的不同深度地壳隆升样式的差异性，成功对上述观点进行了初步地论证。以该研究成果为基础，本项目拟在该区域选择一条垂向剖面，对剖面采集的样品进行多种不同封闭温度热年代学方法测试分析；并对年龄结果进行定量模拟解译，试图揭示完整的地壳不同深度层次的岩石隆升样式。把获得的地壳隆升速率与地表剥蚀强度进行对比，分析二者相互关系；判定是地表剥蚀还是构造活动诱发了该地区地壳隆升。以期对地表剥蚀作用诱发地壳构造活动这一新观点进行有效论证；建立地球外动力因素主导下的活动造山带地质演化模型。