秦岭北麓渭河中上游流域构造地貌分析

Tectonic Geomorphology Analysis of the Middle and Upper Reaches of Wei River in the Northern Qinling Mountains

分析面积-高程积分值空间分布特征有助于理解流域地貌构造形态和发育特征。以ALOS-PALSAR合成孔径雷达干涉SAR生成的12.5 m分辨率DEM数据,对渭河中上游以南秦岭北麓之间区域的面积高程积分(HI)空间分异特征及其对应的地貌构造形态差异和地表过程进行了研究。研究工作首先分析了面积高程积分地学含义及面积空间依赖性,根据分析结果,应分别选择[1600,10800),[10800,22000)集流阈值区间分析研究区域HI值对岩性、构造响应。结果表明:(1)秦岭北麓渭河中上游,HI值从SW向NE递减,表明区域构造活动在该方向上递减;(2)在小尺度空间上,HI值指示Ⅲ、Ⅳ区的岩性抗侵蚀能力与实际抗侵蚀能力不一致,分析表明在Ⅲ、Ⅳ区内可能存在NNE向的断裂,造成其东西两侧抬升幅度差异大;(3)清姜河和藩溪河流域面积高程积分曲线呈凸型,处于幼年发育阶段,其余呈S型,处于壮年发育阶段。研究区域构造抬升强度大于地表侵蚀强度,岩性对小空间尺度上HI值的影响较大,而构造对大空间尺度上HI值的影响较大。该研究结果对流域地貌构造运动程度反演起到了至关重要的作用。

The spatial distribution characteristics of hypsometric integral are helpful to understand the geomorphological structure and development characteristics of the basin.Taking the 12.5 m resolution DEM data generated by ALOS-PALSAR synthetic aperture radar interferometric SAR as the source data,the spatial differentiation characteristics of hypsometric integral between the northern Qinling mountains and the middle and upper reaches of the Weihe river,and the corresponding geomorphological and structural differences and surface processes were analyzed and studied.Firstly,discussing the geographic implication and spatial area dependence of hypsometric integral.Based on these analyses,the threshold values of[1600,10800),[10800,22000)were chosen respectively to analyze the HI response to the lithology and tectonic climate of the study area.The research indicates:(1)The erosion resistance of the Laojunshan rock mass in the northern foot of the Qinling mountains is greater than that of the Baoji rock mass,and the lithology is positively correlated with the HI value.(2)In small-scale space,the HI value indicates that the lithological erosion resistance of areaⅢandⅣis inconsistent with the actual lithological erosion resistance.The analysis indicates that there may be NNE-oriented faults in theⅢandⅣzones,resulting in differences in the elevation of the east and west sides.(3)The hypsometric curve of the Qingjiang river and the Fanxi river Basin is convex and in the stage of aging development.The rest is S-type in the youth development stage.The structural uplift strength of the study area is greater than the surface erosion strength.Lithology has a great influence on the HI value at the small spatial scale,while the structure does at the large spatial scale.The results play an important role in the inversion of geomorphologic movement degree.