白沙含油超浅成脆韧性剪切带各向异性体的特征及成因

FEATURES AND GENESIS OF THE OPTICAL ANISOTROPICITE IN THE BAISHA OIL BEARING BRITTLE AND DUCTILE SHEAR ZONE

湘西泸阳县的白沙镇西侧羊角岭发育了一条含油超浅成脆韧性剪切带。该剪切带中的主体岩石是含凝析油瘤状灰岩，其形成深度不超过３０００ｍ，岩石中的一般有机质（沥青）反射率Ｒｏ值介于０６９％～０７２％之间，处于低中成熟阶段，而其中的部分沥青体则发育了强烈的光学各向异性，其Ｒｏ，ｍａｘ为２５２％～３２０％，Ｒｏ，ｍｅｄ为１０１％～１８４％，Ｒｏ，ｍｉｎ为０３４％～０８１％，最大双反射率值可达８７％。白沙含油超浅成脆韧性剪切带的各向异性体呈不规则碎片状或细条带状，根据其形态及“消光”特点可以分为椭球状、羽状、条带、环状、螺旋状等几种，其成因与岩浆热液作用（叠加了部分构造应变）有关。凝析油也是岩浆热液作用的产物。

Not far from westen Baisha of Luyang county in western Hunan province,there is a supper hypabyssal oil bearing shear zone,in which organic matter(bituminite)relectance R o changes from 0.69% to 0.72%. Nevertheless, parts of bitumenite have the considerable properties of strikely optical anisotropy,whose R o,max ranges from 2.52% to 3.20%, R o,med is from 1.01% to 1.84% and R o,min is from 0.34% to 0.81%, and the maximum bireflectance gets to 87%. The optical anisotropicite in the Baisha oil bearing supper hypabyssal shear zone has the irregular and/or fine belt like shapes.Based on their shapes and optical anisotropic characteristics,the optical anisotropicites may be divided into five types:elliptical,feather,banded,ring like and spiral anisotropicites.