地理学报 ›› 2003, Vol. 58 ›› Issue (5): 757-764.doi: 10.11821/xb200305015

• 气候环境 • 上一篇    下一篇

西藏枪勇冰川冰下富碎屑化学沉淀特征与冰下过程

罗日升,曹峻,刘耕年,崔之久   

  1. 北京大学环境学院,北京 100871
  • 收稿日期:2003-02-25 修回日期:2003-05-29 出版日期:2003-09-25 发布日期:2003-09-25
  • 作者简介:罗日升 (1980-), 男,博士生, 主要从事地表过程与环境变迁研究。E-mail: luorisheng@pku.edu.cn
  • 基金资助:

    国家自然科学基金项目(40271014;90102016)

Characteristics of the Subglacially-formed Debris-rich Chemical Deposits and Subglacial Processes of Qiangyong Glacier

LUO Risheng, CAO Jun, LIU Gengnian, CUI Zhijiu   

  1. College of Environmental Sciences, Peking University, Beijing 100871, China
  • Received:2003-02-25 Revised:2003-05-29 Online:2003-09-25 Published:2003-09-25
  • Supported by:

    National Natural Science Foundation of China, No.40271014; No.90102016

摘要:

西藏枪勇冰川是我国现代大陆性冰川之一,在其外缘冰床背冰面的基岩表面和节理裂隙中发现了富碎屑化学沉淀,为研究冰岩界面的物理、化学过程提供了良好载体。对该区富碎屑化学沉淀理化特征的研究表明:枪勇冰川冰下存在压力融水,冰下碎屑,特别是陆源气溶胶粉尘来源的碎屑,能与融水及其中溶解的CO2发生化学反应,释放出Ca++;Ca++随融水向下游方向迁移,在冰床背冰面,由于上覆压力减小,融水中的CO2逸出并发生复冰作用,使融水中的Ca++重新富集,形成CaCO3沉淀,并将融水中的粉砂粘粒碎屑胶结,形成富碎屑化学沉淀;枪勇冰川冰下融水的存在,证明其冰下存在温度接近融点的融区,有类似于温性冰川的滑动过程。

关键词: 西藏枪勇冰川, 冰下化学沉淀, 冰下过程, 大陆性冰川

Abstract:

Subglacially-formed debris-rich chemical deposits were found both on bedrock surface and in bedrock crevice at the edge of Qiangyong Glacier, one of the continental glaciers in Tibet. Grain size distribution, internal structures and chemical components of the chemical deposits were analyzed. It can be inferred that the temperature of some parts of the ice-bedrock interface is close to melting point and there exists pressure melting water under Qiangyong Glacier. Debris, especially those from continental aerosols, can release Ca++ in the water. At the lee-side of obstacles on glacier bed the CO2 in the melted water might escape from the water and the melted water might refreeze due to the dramatically reduced pressure, making the enrichment and precipitation of CaCO3. The existence of subglacial melting water and the process of regelation under Qiangyong Glacier indicates that sliding could contribute some proportion to the total movement of Qiangyong glacier and it belongs to multiplex cold-temperate glaciers.

Key words: Qiangyong Glacier, subglacially-formed chemical deposit, subglacial process, continental glacier