Geologic and geomorphologic evidence from the Shaluli Mountain indicates that the planation surface that formed in the Late Tertiary disintegrated during the Late Pliocene-Early Quaternary. At the same time, rift ba- sins appeared on some parts of the planation 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 and 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 Move- ment, and coupled with global glacial climate, and 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 Pla- teau.
ZHOU Shangzhe1,2, XU Liubing1, CUI Jianxin1, ZHANG Xiaowei1 & ZHAO Jingdong1 1. National Laboratory of Western China’s Environmental Systems of Ministry of Education of China and Department of Geography, Lan- zhou University, Lanzhou 730000, China
The Shaerqiaoke Gravel, more than 400 m in thickness, on the north piedmont of the Tianshan Mountains, is located at the exit of the Urümqi River Valley and belongs to the Molasse construction of the Tianshan Mountains. Another uplift event with the tectonic boundary expansion ended the deposition of the Shaerqiaoke Gravel, and resulted in folding, faulting and down-erosion in the frontier of the deposit. The ESR dating indicates that the top of the Shaerqiaoke Gravel accumulated before 1148 kaBP, probably responding to the Kunlun-Huanghe movement of the Qinghai-Tibetan plateau. After that time, erosion-deposition cycle occurred and 9 terraces developed. The TL and ESR dating techniques were employed to date these terraces, and the results indicate that Terrace 3 was formed at MIS 6. Terrace 2 at Houxia also developed simultaneously. Terraces 5 and 6 were accumulated in 338 kaBP and 562-591 kaBP, respectively. The oldest glaciation, named Gao Wangfeng, correlates to MIS 12.
