藏东南崇山构造带南段新生代剪切变形、剥露机制及区域构造意义

The Chongshan tectonic belt is an important belt in Southeast Tibet, which plays an important role in the Cenozoic Indo-Eurasian plate collision, post-collision and lateral rotational extrusion of the Sundaland block. Based on systematic geological survey and fine divisions of outcropping-scale rock units and metamorphic deformation zones, analysis of deformation structure of each unit rock and microscopic observation, this project makes an in-depth study of macroscopic structural framework, rock composition and deformation characteristics of the southern section of Chongshan structural belt. At the same time, the temperature, pressure conditions and strain characteristics of shear deformation are restrained by many methods, such as deformation mineral associations, crystallographic fabric of deformation minerals and metamorphism. Meanwhile, carrying out the analysis of tectono-thermochronology to determine the activity time, thermal evolution and exhumation characteristics of the Chongshan tectonic belt. Through the above studies combined with the tectonic characteristics and thermal evolution of other complexes in the Sanjiang area, Southeastern Tibet, the contribution of lithospheric (crustal) viscous flow to the lateral escape of the Sundaland massif will be discussed.

崇山构造带是藏东南一条重要的地质构造带，在新生代印度-欧亚板块碰撞、后碰撞及巽他地块侧向旋转挤出过程中起着重要的调节作用，其新生代构造特征和剥露机制对于理解巽他地块逃逸过程中的岩石圈变形机制有重要启示。本项目基于系统地质调查和精细的野外露头尺度的岩石单元及变质变形带划分、各单元岩石变形构造解析与室内显微观察和测试分析，深入研究崇山构造带南段的宏观构造格架、岩石组成及其变形特征。同时，根据变形构造组合、变形矿物结晶学组构、变质反应等来多种方法约束构造带剪切变形的温度、压力条件和应变特点；开展构造-热年代学分析，确定崇山构造带活动时限和热演化与剥露特征。通过上述研究，并结合藏东南三江地区其他杂岩的构造特征和热演化，进而探讨岩石圈（地壳）黏性流动对于巽他地块侧向逃逸的贡献。

距今约55Ma的印度-欧亚大陆碰撞和随后的后碰撞过程对于青藏高原及其周缘中下地壳活动、地壳结构形成及演化具有重要影响。由此所引起的藏东南巽他地块中下地壳物质发生了侧向流动已被广泛接受，但对于地壳物质流动的特点、表现型式及其机理仍然存在广泛的争议。前人提出了多种模式解释藏东南地区侧向碰撞带的响应，比如刚性块体挤出，中下地壳渠道流动以及地壳增厚等模式。在巽他地块内部以及板缘存在的变质杂岩，例如，西盟，玉龙以及崇山杂岩，对于解释印度-欧亚碰撞过程中藏东南物质的流动型式提供了新的重要线索。本研究选择藏东南崇山杂岩和玉龙杂岩作为研究对象，通过精细构造解析、变形显微构造、组构与岩石变形机制分析，年代学分析等技术，系统开展了穹隆宏观构造特征及构造格架、剥露机制、构造演化与区域构造意义研究，进而探讨岩石圈（地壳）黏性流动对于巽他地块侧向逃逸的贡献。