郯-庐断裂带南段深层次的塑性变形特征及区域应变场

本文研究了郯-庐断裂带南段深层次所表露的塑性构造现象,着重测量和分析了大量的变形砾石,从而确立属韧性平移断裂,具有恒体积的平面应变与不均一的简单剪切位移场特征,产生强烈的压缩与拉伸,并伴随有同变形期的动热变质带。同时还初步确定了四个垂深不同层次的平移剪切模式

THE PLASTIC DEFORMATION CHARACTERISTICS AND REGIONAL STRAIN FIELD ON THE SOUTHERN SEGMENT OF THE TANCHENG-LUJIANG FAULT ZONE

The studied segment shows its major, transcurrent ductile shear zone with a considerable sinistral displacement. The rock formation (Pt-T1+2) at a depth of 5-15km may have cropped out in this area during its and subsequent erosion, many plastic-deformed strctures in it. The deformed zone was involved in the Indo-China orogeny.On the basis of measurements and analyses on a lot of pebbles within the shear zone, it is known that K1 (the Flinn') is 1.178 and 1.053, which suggests a variation of simple shear and a plain strain with a constant volume of the studied zone. The intensely deformed belts are generally 40-50km in width, with an average a/c ratio of 27.68 and the maximum more than 87.37. The intensity of strain decreases rapidly with increasing distance from the shear fault zone, as well as with decreasing" .depth to which the fault goes. For the Pt formation at the greatest depth, a/c value ranges from 30.58, Zr-12.71-12.98, Z2-2.54, and G-1.50.It follows that the differential horizontal slip may occur between various structures. On the condition that the elongation strain e1 and e3 are 4.95 and -0.817 within the intensely deformed belt, respectively,the belt in question has been elongated 164.23km in length and shortened 272.5km in width, to a corresponding 200km and 50km for the time being.The deformed belt was associated with syntectonic dynamothermal metamorphism, represented by greenschist facies and retrogressive metamorphism of early amphibolite ones.The internal belt was formed by high shear strain, with an angle ranging from 0-20° and a shear strain culculated to be more than 11.34.Developed here are four sorts of models involving viscous shear, ductile shear, ductile-brittle shear and brittle shear within the earth's crust