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《ACTA GEOGRAPHICA SINICA》 1994-04
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OBSERVATION AND CONSIDERATION ON THE GELIFLUCTION IN THE ALPINE PERIGLACIAL ENVIRONMENT OF THE TIANSHAN MOUNTAINS

Liu Gengnian(Department of Geography,Peking University,Beijing 100871)Xiong Heigang(Department of Geography,Xinjiang University, Urumqi 830004)  
Field survey and laboratory analysis have been conducted to research the gelifluction in the alpine periglacial environment of the Tianshan Mountains since 1990. The gelifluctions distribute at 2500─3600 meters above sea level. on the northward slope with slope angles of 10°─31°. The length of the gelifluction ranges 7─28. 4 meters. the width 6─30 meters and height 0. 7─4 meters.Most of the gelifluctions have lobate forms with a ratio of length to width less than 1. and a few of them have tongue forms with length to width ratio greater than 1. The slope gradient of the steep front of the gelifluctions ranges 27. 5°─85°.Forming and developing in active layer of the alpine permafrost zone. the gelifluction is mainly forced by gravity and freeze─thaw action. Based on the data from field pitting and laboratory analysis. it shows that grain─size and water content are stratified in the gelifluctions. The debris in gelifluction is oriented parallel to ground surface. The permafrost table under active layer forms a water─proof plane and offers a sliding plane for gelifluction.The moving rate of the gelifluction is measured at 2 800─3 600 meters above sea level where the mean annual temperature ranges-3℃--5. 3℃ and the mean annual percipitation ranges 430-850 mm. The surface moving rate of the gelifluction is 2. 1─18. 77cm/a. and the mean rate is 11. 14cm/a. The maximam front advancing rate of the gelifluction is 6. 76cm/a. and the mean rate is 1. 86cm/a. It shows that the surface moving rate is greater than that of the front advancing rate.The mean advancing rate of the middle part is 3.1cm/a, while the sides is 0. 83cm/a. This shows that the middle part moves more actively than th both sides.
【Fund】: 国家自然科学基金
【CateGory Index】: P931.4
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