河南西峡寨根地区韧性剪切带中斜长角闪岩角闪石组构特征的探讨

本文通过对秦岭造山带核部,河南西峡寨根地区角闪岩中角闪石组构及其与韧性剪切带关系的研究,得出几点认识:（1）角闪石的优选方位受控于韧性剪切带,随着韧性剪切作用的加强,L构造岩愈趋典型;（2）分析角闪石中光率体轴Ng与结晶C轴的关系,Ng轴偏于一个方向,表明受剪应力所致;（3）通过角闪石C轴与剪切带边界关系的研究,确定剪切带为左旋剪切性质;（4）据角闪石组构及韧性剪切带与其它构造相互关系,恢复秦岭造山带的历史,至少经历了区域动热变质变形阶段、韧性再造阶段和脆性改造阶段。

A PRELIMINARY STUDY ON HORNBLENDE-FABRIC OF AMPHIBOLITE IN THE DUCTILE SHEAR ZONE OF ZHAIGEN,XIXIA COUNTY,HENAN PROVINCE

Abstract Based on the study of the hornblende-fabric of amphibolite and its relation to the ductile shear zone in Zhaigsn, Xixia county, Henin Province, some preliminary conclusions can be drawn as follows: (1) The preferred orientation of hornblende is controlled by the ductile shear zone. The L-tectonite becomes more typical with the enhancement of ductile shearing. (2) According to the relationship between the Ng梠ptical indicatrix axes and C-crystallographic axes for hornblendes,the one preponderant direction of Ng-axes indicates a monoclinic distribution of stress. (3) In the light of the relationship between the preferred orientation of C梒rystallographic axes for hornblendes and he boundary of the shear zone, it is believed that the shear sense is sinistral. (4) On the basis of the relationship between the hornblende fabric, the ductile shear zone and the other structures, it is inferred that the evolution history of the Qinling Orogenic Belt can be divided at least into three stages: regional dynamothermal metamorphism, ductile reworking and brittle reformation.