基于精密水准的鄂尔多斯西北缘现今垂直运动分析

鄂尔多斯块体受青藏块体和华北块体的挤压,在其周缘形成一系列褶皱和压性断层,构造较为复杂。本文利用1980、1990和2014这3期精密水准资料计算了鄂尔多斯块体西北缘的垂直运动速率,分析结果表明:① 位于阴山断块隆起与鄂尔多斯断块隆起之间的河套盆地相对下沉,其中临河盆地最为明显,下沉速率为2-4mm/a,位于鄂尔多斯块体西缘的吉兰泰-银川断陷带沉降速率有所减缓,目前沉降速率约为2mm/a;② 整个测区表现为明显的山区上升、盆地下沉的继承性运动;③ 穿过乌拉山北缘断裂和磴口-本井断裂的2条水准剖面显示断裂两侧的垂直运动速率差异小于0.5mm/a。

Current Vertical Motion Analysis of Northwestern Margin of Ordos Based on Precise Leveling

Ordos block was squeezed by the Qinghai-Tibet an block and North China block, and the tectonic activity was intense. In the periphery of Ordos block, there was a series of wrinkles and compressive faults with complex constructure. This paper used three-phase data of 1980, 1990 and 2014 to calculate vertical velocity of northwestern margin of Ordos and the analytical results indicated that ① the Hetao basin between the rise of Yinshan fault block and Ordos fault block relatively sank, in which Linhe basin was the most evident and the sink rate was about 2-4mm/a. The sink rate of Jartai-Yinchuan rift zone on the western margin of Ordos block slowed and the sink rate was about 2mm/a; ② the whole testing zone exhibited the evident inherited movement characterized by mountain rise and basin sinking; ③ the two leveling section through the northern margin fault and Dengkou-Benjing fault showed that the difference between vertical velocities flanking fault was less than 0.5mm/a.