鲜水河断裂带附近地区的区域地貌特征

THE REGIONALLY GEMORPH-ICAL FEATURES OF THE AREA OF THE XIAN SHUIHE FAULT-BELT STRETCHING OF WESTERN SICHUAN, CHINA

在野外考察的基础上,运用定量与定性相结合的分析方法,从山地正地貌和沟谷负地貌两个方面论述了鲜水河断裂带附近地区的地貌特征.认为,山地正地貌主要是第四纪以来强烈断块差异性抬升所形成的断块山,海拔高,高差大,山顶夷平面保存完好,山坡坡形复杂,垂直气候地貌带发育,海拔超过4000m的山岭第四纪冰川作用强烈;沟谷负地貌主要是沿断裂发育并经流水改造而成的断层谷,主谷谷坡有两级剥蚀面和1—5级河流阶地,曾在多处发生过河流的分流与改道.特别应该指出的是,夷平面的解体、河流的改道、强烈的冰川作用同鲜水河断裂带的强烈活动在时间上是同步的.

The author, based on his field work, in this paper gives out the geomorphical features of the area of the Xianshuihe fault-Belt stretching by quantitative and quantitative analysis from the both aspects of positive and negative landforms of mountainsi gullies and valleys. With a big altitude and relief, a good conserve of penplain on mountain tops, a complicated form of slopes and a good developincfit of vertical climato-morphogenesis belts, the posi-tive landforms of mountains are mainly the fault-block ones formed by the intensely different uplift of faultblocks since Quaternary. The ranges which has the altitudes more than 4000 m was glaciated strongly in Quaternary. The negative land-forms of gullies and valleys are mainly fault-valleys which develop along the faults and have been modified by fluvial processes. There are two steps of etchplains and one to five steps of terraces on both slopes of main vallys, and several divergences of trends and changes of flowways of rivers. Specially, it should be pointed out that the disintegration of penplains, the changes oi river flowways and intense glaciation have time synchroism to the intense acting of the Xianshuihe fault-belt itself.