三峡库区坡地地貌过程的速率  

Rate estimation of geomorphic process of the slope in the reservoir area of Three Gorges Project

作　　者：韩志勇[1] 李徐生[1] 胥勤勉[1] 陈可锋[1] 杨达源[1] 

机构地区：[1]南京大学城市与资源学系,南京210093

出　　处：《地理研究》2006年第1期71-78,共8页Geographical Research

基　　金：国家自然科学基金项目(40272126);国土资源部"三峡库区岸坡第四纪堆积物特征及沿江公路稳定性研究"项目资助

摘　　要：在重庆奉节至湖北巴东一带三峡库区,存在两类坡地,分别是深层风化坡地与崩积—残坡积坡地。这两类坡地上,堆积物的稳定性差,表现为剥蚀、堆积的速率大。堆积物的累积速率可粗略地依据热释光年龄来估计。据此我们推测深层风化坡地的浅层滑坡周期大约是1.5ka,对应的堆积速率大约是33cm/ka。崩积—残坡积坡地上主要的陡崖崩塌发生周期是40ka^60ka,坡地中部的累积速率大约是4cm/ka。在崩积—残坡积坡地上常见生长的树木因堆积物蠕滑而变形,树木变形程度反映了蠕滑速率,据此估算的蠕滑速率是非常可观的,这既是坡地中部的剥蚀速率,可能也在一定程度上反映了坡地下部堆积物的物质供应速率。这些认识可能对滑坡与水土流失的治理有参考价值。In the area of Three Gorges, two slope types, namely the deep weathering slope and the colluvium-debris slope, are identified according to our field survey from Fengjie to Badong. Deposits on the deep weathering slope are mainly composed of eluvial materials, and the shallow layer landslide is probably one of the forms of deposit accumulation on the lower part of the slope. The colluvium-debris slope is characteristic of the occurrence of escarpment on the upper part of the slope. Deposits here can be treated as the assemblage of two end members, i. e. , the collapsed block mass and fine slopewash. The amount of the collapsed blocks decreases downslope, while the slopewash layer thickens gradually. The poor stability of deposits on these two types of slopes is revealed by the high rate of denudation and accumulation. The depositing rate can be roughly estimated by dividing total thickness by the deposition age. However, this approach is complicated by the lack of reliable dating of the slopewash. Since the thermoluminescence signals of the slopewash are not completely bleached when deposition, the measured ages can only be treated as the maximum ages in general. As a result, the activity period of the shallow layer landslide on the deep weathering slope is evaluated to be about 1.5ka, the corresponding deposition rate is about 33cm/ka. The main period of the collapse of escarpment is 40ka-60ka, and the deposition rate on the middle part of the colluvium-debris slope is approximately 4cm/ ka. The distorted trees are often found on this type of slopes. The distortion is caused by deposit creeping, and the distortion extent is an indicator of the creeping rate. The consid- erable high creeping rate is the denudation rate on the middle part of the slope, as well as the rate of detritus supply to the lower part of the slope. This shows the denudation rate and the deposition rate vary greatly from one place to another place. Although the periodicity of earthy landslide based on the deposition rate cannot be directly de

关 键 词：三峡 坡地过程 热释光 滑坡 

分 类 号：P931[天文地球—自然地理学]