洮河流域层状地貌与河谷发育过程研究

地貌演化与河流发育是传统地貌学研究的核心内容之一，尤其是青藏高原周边水系的形成演化记录着高原隆升和环境变化的地质信息，倍受国内外地学界关注。鉴于一条河流的近代地质历史主要反映在河谷地貌上，同时保存在谷肩和分水岭地带的夷平面、剥蚀面可以为现代河谷的发育提供时空起点，因此研究这些地貌面的时空展布特征，是重建流域地貌和水系演化的最佳途径。本项目拟通过对洮河流域夷平面、剥蚀面的研究，结合花岗岩体的低温热年代学研究,重建该区新生代期间山地隆升-剥蚀过程；结合夷平面相关沉积的古流向研究，揭示洮河、黄河、岷江等古水系之间的联系；通过对阶地、古滑坡、堰塞湖相沉积时空展布特征的研究，获取现代洮河河谷地貌的发育过程；通过对阶地及其漫滩沉积物的地貌地层学研究，提取河流过程对外界环境变化的响应；最后综合贯通上述研究结果，重建洮河流域水系的发育过程，揭示高原东北缘地表系统相互作用及其时空演化规律。

Landform evolution and river origion are core topics in classic geomorphic studies. Especially, geologists have paid much attention on the rivers close to the Tibetan Plateau, which the formation and development process records abundant information of tectonic uplift and climate change. The recent geologic history of a river is mainly recorded in valley landscape, and the planation surface, erosion surefuces, which preserved in divides area, can indicate the origin of present river. In view of these, study on the temporal and spatial distribution characteristics of these geomorphic surfaces is an effective method to reconstruct the drainage landform and fluvial evolution. This project plans to reconstruct the uplift-erosion process during Cenozoic in our study area, via researching on the temporal and spatial distribution characteristics of the planation surfaces and erosion surfaces. Associated the paleo-current studies on related sediments of planation surfaces, imply the correlation among Paleo- Taohe River, Yellow River and Minjiang River etc. With the temporal and spatial distribution characteristics of terraces, paleoslides and dammed lakes deposites, we can reveal valley development of modern Taohe River. Based on the studies on high resolution stratigraphic research of terrace and floodplain deposites, imply the response process of fluvial system to external environment change. In the last, integrate these results to reconstruct the development process of Taohe River, reveal the interaction processes of tectonic, climate and surface erosion, temporal and spatial evolvement principles of the Earth surface systems in the northeastern Tibetan Plateau.