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1970年和2013年龙门山构造带南段分别发生了大邑西Ms 6.2级地震和芦山Ms 7.0级地震,表明该地区新构造运动相对活跃,为研究构造-地貌-水系的理想场所。基于DEM数据,提取了龙门山南段山前地区的西河(R1)、出江河(R2)、斜江河(R3)、文井河(R4)、三郎河(R5)和泰安河(R6)6条河流及其次流域,通过计算得到这6条河流及其次流域的面积-高程积分值和面积-高程积分曲线,对该地区的构造活动、地貌演化特征进行分析。结果显示:(1)研究区域总体上面积-高程积分值从NW向往SE向递减,表明从NW向往SE向区域活动性整体上在减弱,同时代地层出露的时间越来越晚。(2)研究区域双石—大川断裂上盘SW段的面积-高程积分值比NE段高,表明双石—大川断裂活动性从SW向往NE向有减弱的趋势。(3)随着前展式逆冲推覆作用持续,按照Ohmori模式推测出山地、丘陵、平原的发展模式:1山地,未来山地区域会继续长高,其面积-高程积分渐渐接近0.6(F阶段),面积-高程积分曲线开始从S形向凸形方向发展,山地型河流会由壮年期向幼年期发育;2丘陵,其面积-高程积分曲线开始从凹形向S形发展,丘陵型河流会由老年期向壮年期发展,到达壮年期之后,会进入山地的发展模式;3平原,虽然逆冲抬升作用会增强,但地形雨降雨带也会逐渐靠近,反而造成其剥蚀强度大于抬升强度,其发展模式会渐渐进入丘陵模式。
In 1970 and 2013, respectively, the Dayton West Ms 6.2 earthquake and Ms 7.0 Lushan earthquake occurred in the southern segment of the Longmen Shan tectonic belt, indicating that the Neotectonics movement is relatively active in this area and is an ideal place for studying the tectono-geomorphology-water system. Based on the DEM data, Xihe (R1), R2 (outlying river), R3 (R3), R4 (R4), Saburo (R6) and Tai’an6 After calculating the area-elevation integral value and area-elevation integral curve of these 6 rivers and the second river basin, the tectonic activities and the evolution characteristics of the landscape are analyzed. The results show that: (1) The overall area-elevation integral decreases from NW to SE, which indicates that the activity from NW to SE is weakened overall, and the stratigraphic exposure is getting later and later. (2) The area-elevation integral value of the SW segment of the Shangshi-Shuanghuan fault in the study area is higher than that of the NE segment, indicating that the activity of the Shimen-Dajing fault tends to decrease from SW to NE. (3) With the continuation of the foreshock thrusting, the development pattern of the mountains, hills and plains is inferred according to the Ohmori model: 1 The mountainous region will continue to grow in the mountainous region in the future, and its area-elevation integral gradually approaches 0.6 (F Stage), the area-elevation integral curve began to develop from S-shape to convex shape, and the mountain-type river developed from adolescence to juvenile. In the second hilly region, the area-elevation integral curve began to develop from concave to S- The river will develop from old age to mature age and will enter the mountainous development mode after reaching the mature age. In the third plain, though the effect of thrust uplift will be enhanced, the topographic rainfall rain belt will gradually close, but the denudation strength will be greater than the uplift Strength, its development model will gradually enter the hilly mode.