关键词: 昆仑山垭口, 成层坡积, 末次冰期, 湿冷

Abstract: The stratified slope deposits (gr zes lit es) locate on the east or southeast ward slope base and distribute 4 100 m above sea level at Xiaonanchuan of Kunlunshan Pass. The typical profile is near 5y Daoban by the Qinghai Tibet Highway at Xiaonanchan, with a total thickness of 27m. The profile is composed of three layers, the base layer is of residue with a thickness of 2m～3m, the middle layer is of stralified slope deposits with a thickness of 10m～15m, and the top layer is of loess with a thickness of 9m. According to the grain size and sedimentary structures, the middle stratified slope deposits can be divided into two parts, the lower part is greater in grain size and thicker in bedding, and is evolved from gelifluction, the upper part is smaller in grain size and thinner in bedding with an average bet thickness of 0.4cm. The fragments of the upper part show a prolonged and repeated frost action, and the bedding shows that the deposit is formed by sheet wash that is supplyed by perennial show patch on the upper slope. The stratified slope deposits began at 60000aBP and ended at 44000aBP. The loess on top layer was formed in a cold dry climate at 38000aBP. Analysis data of sedimentary structures, grain size, chemical composition, scanning electron microscope and dating show that the stratified slope deposits were formed in the early period of Last Glaciation ( 60000aBP～44000aBP), with a climate change from cold wet tl cold dry. The loess on the stratified slope deposits reflects a remarkable cold dry condition in the Last Glaciation and Holocene. In general, this profile shows projectively a cold wet climate instead of a cold dry climate in the early period of Last Glaciation in the area of Kunlunshan Pass. This does not fit with the monsoon model, therfore, it is believed that this area was influenced by the westerlies in the early Last Glaciation.

Key words: Kunlunshan Pass, Stratified slope deposits, Last Glaciation Cold wet