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中国沙漠 ›› 2000, Vol. 20 ›› Issue (4): 443-446.

• 论文 • 上一篇    下一篇

青海湖西岸风成沙丘特征及成因

宋春晖1, 方小敏1, 师永民2, 王新民2   

  1. 1. 兰州大学 资源环境学院, 甘肃 兰州 730000;
    2. 西北地质研究所, 甘肃 兰州 730020
  • 收稿日期:1999-09-07 修回日期:2000-02-16 出版日期:2000-12-20 发布日期:2000-12-20
  • 作者简介:宋春晖(1959-),男(汉族),河南清丰人,硕士,副教授,主要从事沉积相和沉积环境研究工作。
  • 基金资助:
    国家杰出青年科学基金(49928101);西北地质研究所资助项目

Characteristics and Formation of Aeolian Dunes on Western Shore of the Qinghai Lake

SONG Chun-hui1, FANG Xiao-min1, SHI Yong-min2, WANG Xin-min2   

  1. 1. School of Resource and Environment, Lanzhou University, Lanzhou 730000, China;
    2. Northwest Institute of Geology Research, Lanzhou 730020, China
  • Received:1999-09-07 Revised:2000-02-16 Online:2000-12-20 Published:2000-12-20

摘要: 沙漠化是青海湖周围生态环境恶化中一个非常突出的问题,尤其湖西岸沙丘是近十多年来才形成的风沙堆积,并逐年扩大,已成为青海湖区第二大风沙堆积区。通过对青海湖西岸沙丘的分布、形态、物源及粒度特征的分析,对其形成进行了研究,并对布哈河三角洲的形成发育与沙漠化之间的关系进行了初步探讨。认为河流的自然摆动和截直造成了该三角洲东北缘的停止发育,加之气候的持续干旱和严重的鼠害,是导致研究区土地沙化、沙漠面积不断扩大的一个主要因素。

关键词: 青海湖西岸, 滨岸沙丘, 物源, 粒度, 成因

Abstract: Desertification is a very obvious problem on the ecological environment,which has steadily deteriorated in the area of the Qinghai Lake.The dunes on the western shore of the Qinghai Lake are a newly evolving area of aeolian sand in recent ten years and are expanding the limits yearly,and the area is the second big depositional area of aeolian sand in the Qinghai Lake region.The dunes on the western shore of the Qinghai Lake distribute along the shoreline on the northwest of the Bird Island and in the northwestern margin of the Buhahe delta,and the dune-field forms a strip with 0.5~1.5 km width and more than 10 km length.The dominant dune types are crescent dunes and dune ranges.The former get mainly near the lake,its windward slope is convex to the lake and the two horn point to 215°~260°.The later get near the land,the main ranges distribute along the S-N direction and the vice ranges distribute in the NE-SW direction.These indicate that the dominant wind in the studied area is in the E-NE direction.Provenance analysis showed that the dunes are featured by the low mineral maturity index and high structural maturity index.The max grain size is lower than 0.5 mm,the grades from 0.25 mm to 0.063 mm are over 92 percent,and the average grain size of sand regularly change from windward slope(0.137 mm) to dune ridge(0.167 mm) and to lee slope(0.19),which indicates the formation process and the moving direction of the dune.The depositional place of the aeolian sand was more than 3 000 m apart from the shoreline of Qinghai Lake,when the Bird Island was 3 800 m apart from the shoreline and the deeph of water was five meters in 1956.The main stream channel of the Buhahe delta was situated on the North of the Bird Island and made that the north part of the delta developed faster than the south part before the 1980's.The delta-plain was linked with the Bird Island in 1979.After 1980,the main channel swayed to the south of the Bird Island because the main channel and the branch channels on the delta plain cut off and swayed to the south step by step.New delta deposit was built up to the south of the old delta,but the northeastern margin of the old delta stopped development without tributary channels and changed to normal lakeshore.So the large sediments of deltaic deposit is the material base of the aeolian dunes and the stopping development of the delta is the formation factor of the aeolian dunes.Accordingly climate continued arid,which led to soil desertification and the area of desert expanded continuously in recent ten years in the studied area.The onshore lake wind(E-NE) blows the well-sorted sand grains on sand bank along the shore-bar and the sands are transported landward,then built up coastal dunes.

Key words: western shore of the Qinghai Lake, coastal dune, provenance, grain size, formation

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