Geomorphologic evolution and environmental changes in the Shaluli Mountain region during the Quaternary

摘要

Geologic and geomorphologic evidence from the Shaluli Mountain indicates that the planation surface that formed in the Late Tertiary disintegrated daring the Late Pliocene-Early Quaternary. At the same time, rift basins appeared on some parts of the plantation surface, and began to accumulate fluvial-lacustrine sediment. These are interpreted as being the response of this region to Phase-A of the Qingzang Tectonic Movement. After this, the Shaluli Mountain continued to rise in several pulses. Faulting and incision by some large tributaries of the Jinsha Yalong Rivers resulted in several rift river valleys and the earliest terraces. Generally, the planation surface in this region had been uplifted to about 3500-3700 m a.s.l. no later than 550-600 ka BP, after the Kunlun-Huanghe Tectonic Movement, and coupled with global glacial climate, resulted in the earliest glaciation recognized so far in the Hengduan Mountains. At the same time, loess was deposited in the Ganzi area of the northern Shaluli Mountain, During the last glacial period, the Shaluli Mountain approached its present altitude and developed several large ice caps, such as the Daocheng Ice Cap and Xinlong Ice Cap, as well as several huge valley glaciers. These paleoglaciers produced some of the most spectacular glacial topography on the Tibetan Plateau.