基于GPS观测分析鄂尔多斯块体南缘现今地壳运动和地应变特征

根据陕西省2001和2002年两期的GPS测站的观测资料，给出了渭河盆地及周邻地区地壳运动速度场和该区现今地壳水平应变场，结果表明：(1)渭河盆地及邻区的运动速率呈现较明显的北东向条带状变化特征，该区有整体不连续性逆时针旋转运动的特征；(2)渭河盆地中部的彬县—西安—蓝田一线存在一个左旋剪切带(东侧)，该左旋剪切带的北部区域与铜川—泾阳—临潼小发震带恰好对应；(3)渭河盆地中部与北部以压应变为主，南部以张应变为主，高值区主要分布在该区主要断裂带的附近，尤其是在宝鸡一太白、渭南—蓝田和合阳—韩城附近分别形成应变高值区，并且应变梯度也较大；该区渭河断裂以北大部分地区以面收缩为主，以南则以面膨胀为主，面应变高值区与压应变高值区以及最大剪应变高值区有着较好的对应关系。

A Study on the Current Horizontal Movement and Strain Field of Weihe Basin and Its Neighboring Area Based on GPS Data

According to GPS data of Weihe Basin and its neighboring region obtained by the Seismological Bureau of Shaanxi Province from 2001 to 2002, we have analyzed current crustal strain field of the region. Its characteristics are as following: (1) The movement in Weihe Basin and its neighboring area indicates obviously north--east belt. The south border of Erdos block seems to take anti--clockwise rotation uncontinuitily. Related to Yulin point, the average rate of movement is about 5.7 mm/a in the zone; (2) In two sides of the Binxian--Xi'an--Lantian ray in the central Weihe Basin there is a left--handed shear belt (east side) which northern area is just corresponding to the earthquake zone of Tongchuan--Jingyang--Lintong--Weinan; (3) There are principal compressive strain in the middle and north parts of the area and tensile strain in the south part. The strain contour--line appears from south to north in general, and high value zone is mostly located near the main faults of Weihe Basin and its neighboring region, especially near Baoji--Taibai, Weinan--Lantian and Heyang--Hancheng higher compressive strain zone as well greater strain gradient value occurred. The north part from the Weihe fault is mainly superfacial contraction and its south is basically superfacial expansion. Surface strain higher zone and compressive strain higher zone and the maximum shear strain higher zone have corresponding relation in some degree.