小秦岭东部区域韧性剪切带研究

STUDY ON REGIONAL DUCTILE SHEAR ZONES IN THE EAST XIAOQINLING

本文首次对小秦岭东部的区域韧性剪切带进行了研究。根据野外调查和室内分析，区域韧性剪切带特征可概括为以下几点：①北部、北中部、中部区域韧性剪切带及闵峪花岗岩体南缘的区域韧性剪切带在区内均可见到；②区域韧性剪切带中出露的动力变质岩以条痕状糜棱岩、糜棱片麻岩和斜长角闪糜棱岩为主，变质作用达角闪岩相；③闵峪花岗岩体南缘的区域韧性剪切带生成于燕山期，剪切方位多次变化，早期为左行，晚期为右行；④其余区域韧性剪切带生成于太古宙末期，并以右行逆冲为主；⑤它们对金矿的形成、富集具有重要作用。

Regional ductile shear zones in the east Xiaoqinling are studied for the first time in this paper. Onthe basis of plenty practical field investigation and the analysis in laboratory, the main characteristics of theregional ductile shear zones in the east Xiaoqinling can be summarized as follows:(1) There exist north and middle regional ductile shear zones in the south of the Wenyu granite in thisdistrict.(2) The dynamical metamorphic rocks are mainly streak mylonite, rnylonitic gneiss and amphibolitic mylonite in these regional ductile shear zones. The metamorphism is amphibolite factes.(3) The regional ductile shear zone in the south of the Wenyu granite was formed during Yanshan movement. The shear-sense is changeable. Early stage is left-handed, while the late one is right--handed.(4) The other regional ductile shear zones were formed during the late Archean. The shear --sense isrigh-handed reverse.(5) Gold mineralization is closely related to the regioanl ductile shear zones.