雅拉香波穹隆韧性剪切带变形特征与剪切作用类型研究

雅拉香波变质核杂岩位于北喜马拉雅穹隆带东端，其拆离断层系的糜棱岩带构成了杂岩核部的外缘，带内主要变形岩石类型为石榴石千糜岩、糜棱状片麻岩和糜棱状花岗岩．糜棱状岩石中宏、微观韧性变形组构丰富，暗示区内存在多种显微变形机制：物质扩散迁移、晶内脆性破裂、粒内滑动及粒间滑动等，3种运动学涡度统计和计算结果表明：雅拉香波变质核杂岩拆离系的剪切作用类型是以简单剪切作为主的一般剪切；剪切带厚度变化为76％左右，属于减薄型：后期纯剪切应变速率比早期的有所增强，这可能与杂岩体核部岩浆岩后期上侵增强，穹隆进一步抬升和脆性垮塌下滑作用相关．

DEFORMATION AND SHEAR TYPE OF THE DUCTILE SHEAR ZONE,YALASHANGBO DOME, NORTHERN HIMALAYA DOME ZONE

The Yalashangbo Dome, located to the east of the Northern Himalayan Dome Zone (also known as the North Himalayan Antiform), has a geometry and structure similar to a classic metamorphic core complex. In the mylonitic zone, the deformed rocks are garnet gneiss phyllonite, mylonited gneiss, and granitic mylonite. Within the deformed rocks in the ductile shear zones, abundant deformational textures in micro and macro scale are developed showing the deformation of rocks in shear zones mainly resulted from the ductile deformation mechanism such as crystal plastic deformation, diffusion and migration of mineral, brittle fracture within crystal and slippage between two particles. Kinematic analyses are made in the shear of the detachment system in the Yalashangbo Metamorphic Core Complex using three techniques. Results suggest this shear zone is a general shear zone, which was thinned and simple shear-dominated.