中部地壳剪切带花岗质岩石变形及其对于构造-岩浆关系的约束:以滇西点苍山为例
发布时间：2018-07-29 06:10
【摘要】：哀牢山-红河剪切带剪切时间的厘定至今存在较多的争议,争议的本质更确切地说是对于剪切带内及其附近剪切作用与岩浆作用认识的差异。点苍山杂岩是位于哀牢山-红河剪切带北端的一个杂岩体,由西部的深变质岩、东部的叠加退变质带和不同时代的花岗质岩石组成。为了正确厘定剪切前、剪切期(包括剪切前期和剪切后期)、剪切后花岗质岩脉,剪切作用过程中构造变形与岩浆作用之间的关系,同时对哀牢山-红河剪切带剪切时间进行新的约束,本文围绕点苍山杂岩开展详细的宏观构造解析、显微构造观察和组构分析,以查明岩体(脉)岩浆流动构造和晶质塑性变形构造,同时对同剪切岩脉开展锆石U-Pb学分析。结果显示,剪切不同阶段就位的花岗质岩石具有不同的宏观构造、显微构造与组构特征。现今所见岩石变形构造、显微构造和组构特点一方面取决于递进剪切变形作用过程中的时间早晚,另一方面还与它们在递进剪切变形作用过程中的构造位置有密切联系。获得两组同剪切年龄为28.54±0.15Ma和27.31±0.23Ma,其中前者为剪切早期阶段同就位的花岗岩脉,后者为剪切稍晚阶段同就位的花岗岩。研究揭示出就位较晚的岩脉(即后者)因其位于递进剪切变形的高应变带而具有较为复杂的变形构造、显微构造和组构型式,就位较早的岩脉(前者)因在递进剪切变形作用过程中位于低应变带而具有简单的变形构造、显微构造和组构型式,并仍然保留有岩浆结晶组构特点。哀牢山-红河剪切带在28.54~27.31Ma间持续发生着从早期阶段较高温(~700℃),向中期阶段中高温(550~600℃)和晚期阶段低温(低于400℃)环境的递进剪切变形作用。
[Abstract]:The determination of shear time in the Ailaoshan-Honghe shear zone is controversial up to now. The essence of the controversy is the difference between shear and magmatism in and around the shear zone. The Dancangshan complex is a complex at the northern end of the Ailaoshan-Honghe shear zone, which is composed of the western deep metamorphic rocks, the eastern superimposed retrograde metamorphic zone and the granitic rocks of different ages. In order to correctly determine the relationship between tectonic deformation and magmatism during shearing, shearing (including pre-shear and post-shear), post-shear granitic veins, At the same time, the shear time of the Ailaoshan-Honghe shear zone is restricted. The detailed macroscopic structural analysis, microscopic structure observation and fabric analysis are carried out around the point Cangshan complex. In order to find out the magmatic flow structure and the grain plastic deformation structure of the rock mass (vein), zircon U-Pb analysis was carried out for the same shearing vein at the same time. The results show that the granitic rocks in different stages of shear have different macroscopic structure, microstructure and fabric characteristics. On the one hand, the microstructure and fabric characteristics of rock deformation are determined by the time of progressive shear deformation, on the other hand, they are closely related to their tectonic position in the process of progressive shear deformation. The same shear age is 28.54 卤0.15Ma and 27.31 卤0.23 Ma.The former is the same in the early stage of shearing, and the latter is in the same position in the later stage of shear. The study reveals that the late vein (that is, the latter) has complex deformation structures, microstructures and fabric patterns due to its location in the high strain zone of progressive shear deformation. The early emplaced veins (the former) have simple deformation structures, microstructures and fabric patterns because they are located in low strain zones during progressive shear deformation, and still retain the characteristics of magmatic crystallization fabric. In the Ailaoshan-Honghe shear zone, progressive shear deformation occurred between the early stage (700 鈩，
本文编号：2151781
[Abstract]:The determination of shear time in the Ailaoshan-Honghe shear zone is controversial up to now. The essence of the controversy is the difference between shear and magmatism in and around the shear zone. The Dancangshan complex is a complex at the northern end of the Ailaoshan-Honghe shear zone, which is composed of the western deep metamorphic rocks, the eastern superimposed retrograde metamorphic zone and the granitic rocks of different ages. In order to correctly determine the relationship between tectonic deformation and magmatism during shearing, shearing (including pre-shear and post-shear), post-shear granitic veins, At the same time, the shear time of the Ailaoshan-Honghe shear zone is restricted. The detailed macroscopic structural analysis, microscopic structure observation and fabric analysis are carried out around the point Cangshan complex. In order to find out the magmatic flow structure and the grain plastic deformation structure of the rock mass (vein), zircon U-Pb analysis was carried out for the same shearing vein at the same time. The results show that the granitic rocks in different stages of shear have different macroscopic structure, microstructure and fabric characteristics. On the one hand, the microstructure and fabric characteristics of rock deformation are determined by the time of progressive shear deformation, on the other hand, they are closely related to their tectonic position in the process of progressive shear deformation. The same shear age is 28.54 卤0.15Ma and 27.31 卤0.23 Ma.The former is the same in the early stage of shearing, and the latter is in the same position in the later stage of shear. The study reveals that the late vein (that is, the latter) has complex deformation structures, microstructures and fabric patterns due to its location in the high strain zone of progressive shear deformation. The early emplaced veins (the former) have simple deformation structures, microstructures and fabric patterns because they are located in low strain zones during progressive shear deformation, and still retain the characteristics of magmatic crystallization fabric. In the Ailaoshan-Honghe shear zone, progressive shear deformation occurred between the early stage (700 鈩，
本文编号：2151781
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