墨脱断裂地貌特征及其构造意义

Geomorphic Characteristics of Motuo Fault and Its Tectonic Significance

摘要:

墨脱断裂展布于南迦巴瓦构造结的东侧，晚第四纪以来活动强烈，断裂水平运动表现为左旋走滑。为了进一步研究墨脱断裂倾向滑动特征及断裂活动性差异，文章基于DEM数据提取了4对横跨断裂矩形区域内的高程数据，计算获得沿断裂发育的31个流域盆地的面积高程积分值。研究表明，墨脱断裂两侧在同一高度出现对称的4组台地面，且从低到相邻的两级台面的高度差没有出现逐步增大的趋势，表明断裂没有表现出明显的倾向滑动；沿断裂分布的汇水盆地具有较大的面积高程积分值（0.42~0.60之间），反映出墨脱断裂所在区域目前总体表现为强烈的构造隆升；根据汇水盆地面积高程积分值的空间分布特征，区域地壳隆升强度沿墨脱断裂由南至北具有逐渐减弱的趋势，结合断裂地貌形态，认为在强隆升区面积高程积分值对断裂活动性具有一定的指示意义。

Abstract:

The Motuo fault is located at the east of the Namjagbarwa Peak. The fault activity has been strong since the late Quaternary, and the horizontal movement of the fault is characterized by sinistral strike-slip. To further study the movement characteristics of the Motuo fault, the elevation data of four elevations across the rectangular region of the fault were extracted, and the hypsometric integral values of 31 catchment basins along the fault were calculated. The results showed that four sets of symmetrical platform ground appeared at the same height on both sides of the Motuo fault, and the height difference from the low to adjacent two-stage Mesa did not show a gradual increase. This indicates that the fault does not feature a significant tendency to slip. The catchment basin distributed along the fault has a large hypsometric integral value (between 0.42 and 0.6), which reflects a strong tectonic uplift in the Motuo fault region. According to the spatial distribution characteristics of the hypsometric integral value of the catchment basin, the uplift intensity of regional crust gradually decreases from south to north along the Motuo fault. Combined with the fault geomorphology, it is concluded that the hypsometric integral value in the strong uplift area has certain referential meaning to the fault activity.