基于DEM的湘桂交界处夷平面的地貌特征研究

Research on the geomorphological characteristics of the planation surfaces at the junction of Hunan and Guangxi based on DEM

湘桂交界处南岭西段山地上广泛发育了夷平面,而对其地貌特征进行定量分析有助于加深对该区地貌演化的认识.本文基于30 m的DEM数据,在ArcGIS 10.3中,通过均值变点法和最小误差分析法分别限定夷平面的高程和坡度,并结合面积指标,提取了该区的夷平面.结果显示,该区夷平面的坡度介于0~13°,海拔介于1416~1780 m,且主要分布在南山、鸡公山和越城岭上,面积分别为165.41、154.41和83.75 km^(2);夷平面主要切割印支期、加里东期和燕山期花岗岩;结合坡向分析显示,3座山脉的夷平面分布高程大体一致,且接近水平,这表明这些夷平面为一个区域性夷平面的残余面,且该区地形曾经历了漫长的侵蚀夷平阶段,其后期构造抬升以水平抬升为主;夷平面的广泛存在表明该区地形演化还处于地貌侵蚀循环的青壮年期,也是南山牧场形成的地质背景.

The planation surface is widely developed in the western part of Nanling Mountains at the junction of Hunan and Guangxi,and the quantitative analysis of its geomorphological characteristics is helpful to deepen the understanding of the geomorphological evolution in this area.Based on the 30 m DEM data,in ArcGIS 10.3,this paper uses the mean change point method and the minimum error analysis method to limit the elevation and slope of the planation surface respectively,and combined with the area index,it extracts the planation surface of this area.The results show that the slope of the planation surface in this area is between 0~13°,and the altitude is between 1416~1780 m,and it is mainly distributed on the Nanshan Mountain,Jigong Mountain and Yuecheng Mountain,with an area of 165.41 km^(2),154.41 km^(2) and 83.75 km^(2),respectively.The planation surface mainly cuts the Indosinian,Caledonian and Yanshanian granites,and the slope aspect analysis shows that the elevation distribution of the planation surface of the three mountains is roughly the same and close to the level.This shows that these planation surfaces are the remnants of a regional planation surface,and the topography of the area has experienced a long stage of erosion and flattening,and the later tectonic uplift is dominated by horizontal uplift.The widespread existence of planation surface indicates that the topographic evolution in this area is still in the youth of geomorphological erosion cycle,and it is also the geological background for the formation of Nanshan pasture.