东天山康古尔韧性变形带韧性挤压变形特征:以哈密黄山东地区为例

东天山康古尔断裂带和雅满苏断裂带之间石炭纪沉积-火山岩系中发育一条东西向韧性变形带,具两期性质不同的韧性变形,早期韧性挤压性质,晚期右行韧性剪切.对早期韧性挤压变形的宏观构造(糜棱面理、糜棱线理、对称石香肠构造、不对称褶皱等)和显微构造(压力影构造、布丁构造、动态重结晶、不同类型砾石变形特征等)特征做了详细的研究.糜棱岩中砾石有限应变Flinn图解判别岩石类型为L-S和SL型构造岩,三轴应变量的测量均揭示了一般压缩和少部分的平面应变类型.石英亚颗粒旋转重结晶及少量边界迁移重结晶,长石塑性变形、部分膨凸重结晶等变形特征;石英C轴组构揭示中温柱面和菱面滑移为主,后期叠加底面滑移.因此,推测早期韧性挤压变形温度范围在450~550℃.综合区域地质资料,康古尔变形带早期韧性挤压变形形成于300~290 Ma,塔里木板块和中天碰撞闭合后陆内南北挤压环境下.

Ductile-Compressional Deformation of Kanggur Ductile Deformation Zone in the Eastern Tianshan Mountains: A Case Study of Huangshandong Area of Hami City

A east-west trending ductile deformation zone was identified between the Kanggur fault and Yamansu fault within the Carboniferous sedimental-volcanic series in the eastern Tianshan mountains. The deformation zone exhibits different characteristics in its evolutionary process, namely, the early stage ductile compressional deformation, and the later right lateral shear deformation. In this paper, the macrostructure (foliation, lineation, symmetrical boudinage structure and asymmetric fold, etc.), and microstructure (pressure shadow, boudinage structure, dynamic recrystallization, different types of gravel deformation, etc.) of early ductile compressed deformation were studied in detail. Systematic measurement of the finite strains of quartz and triaxial strain rate in mylonites indicates that the strain type in general compression is L-S and LS tectonites. The quartz grains occur as subgrain rotation recrystallization and a small amount of grain boundary migration recrystallization, and the feldspar porphyroclasts are elongated and some are fully bulging recrystallized. Quartz C-axis fabrics (EBSD) reveal that quartz fabrics are mainly middle temperature prismatic slip and rhomb slip system, and the later superimposed low temperature is slip-based. It is suggested that the deformation temperature of the early ductile compressional ranges from 450 ℃ to 550 ℃. Combined with regional tectonic, the early ductile compressional of Kanggur ductile deformation zone was formed in 300-290 Ma, which was related to the intracon-tinental N-S compression environment after collision between the Tarim plate and the middle Tianshan plate.