The Terraces And Evolution Of The Yellow River In Guide

The uplift process of Qinghai-Tibet plateau and its environment change have gradually become into a focus in earth science research. As a unit of tectonic landform, Guide basin is typical and representative, and is an ideal place for studing the uplift and environment change of qinghai-tibet plateau.Study river landforms is one of traditioal and relatively mature methods which usually used to study cenozoic tectonic.The age when river terraces was born is just about the time when the Yellow River appeared in this area, and the characteristic of Qinghai-tibet plateau uplift process can be well indicated by the history and amplitude of downward incision of the Yellow River. As Guide basin is most typical and representative among other basins, it is significant to study the Yellow River's evolution in Guide to help solve debates such as the appeared time of the Yellow River in this area.By analyzing of age data of river terrace in Guide and referring precedent study, we preliminarily discuss the evolution of the Yellow River in Guide, and divide the evolution process of the Yellow River into three stage as:preliminary stage, middle stage and late stage.The uplift of the Yellow Rive in Guide characterized by multi-period, heterogeneity and intermittence. The uplift rates of the Yellow Rive in Guide characterized by multi-period and non-uniform velocity.Guide Basin, in which braided channels developed, was in a relatively descending state since Holocene.Guide Basin finished fluvial-lacustrine deposition. The uplift motion of Qinghai-Tibet plateau may cause the Yellow River erode upward to upper reaches so that it transected Songba Gorge, reached Guide Basin. From then on the accumulative downcutting of the Yellow River is 900m and nine terrace formed, dating the part of the terraces.