拉萨地区重力场异常与断裂构造

The Character of Gravity Field and the Faulted Structure in Lhasa Area

本文以拉萨地区1:100万区域重力调查资料为依据,在对该资料进行处理与解释后,对该地区的重力异常的基本特征进行了研究。拉萨地区重力异常特征总体走向为近东西向,南部高、北部低,南部表现为重力梯级带特征,北部表现为宽大的重力低异常;通过对重力资料处理和分析,结合地质资料和其它地球物理资料,及其断裂构造在重力场上表现出的特征进行断裂识别,共识别出断裂19条(一级断裂4条、二级断裂9条、三级断裂6条),其中的11条断裂是被首次发现,并对识别出的断裂中的几条主要断裂进行了综合解释;东西向断裂发育早、断距大、活动期长,将研究区划成了东西向的条带状结构,北东向和北西向断裂一般发育晚、断距较小,将东西向断裂进行了后期改造,使区内重力场明显具有南北成带、东西成块的基本特征。

Based on the Lhasa area 1.1,000,000 regional gravity survey,researched the basic characteristics of abnormal gravity in this area after handling and interpreting survey. The overall characteristics of gravity abnormalies in Lhasa area are nearly east-west, the height in south,the low in north. The gravity gradient zone present in the south of the area, and the spacious low abnormity present in the north of the area. On the base of treatment and analysis the gravimetric data, associating the geologic information and other physics of the Earth data. The Characters of faulted structure presents in gravitional field identify the fault. There have 19 faults been identified （4 first order,9 second order,ll thrid order）,and 11 faults of them are first identified. Expound the chiefly fault, the fault from east to west develops upper than others, and the fault displacement is big and active state is long. It divides the region of studying into east to west belt frame, the fault from east to north and from west to north develops later than others. The fault displacement is small, and it reforms the fault from east to west in later stage,and make them present essential characteristic of north and south banking ,west and east blocking.