青藏高原东缘山地古冰川沉积物磁化率特点及其影响因素分析  

Magnetic Susceptibility of Glacial Deposits and the Impacting Factors in the Eastern Bordering Mountains of the Tibetan Plateau

作　　者：张威[1] 李媛媛[1] 冯骥[2] 毕伟力[1] 刘鸽[1] 

机构地区：[1]辽宁师范大学城市与环境学院,大连116029 [2]北京林业大学经济管理学院,北京100083

出　　处：《地理科学进展》2012年第11期1415-1425,共11页Progress in Geography

基　　金：国家自然科学基金项目(40971010;40571016;41271093)

摘　　要：湖泊、黄土与古土壤、深海沉积物等连续沉积体的磁化率变化作为环境变化的替代性指标被广泛应用,然而对于非连续、能够反映特定时段气候变化的沉积体,如冰川沉积物的磁化率却较少涉及。本文通过对青藏高原东缘8个典型冰川发育山地冰碛物磁化率进行研究,并与黄土、湖泊、深海沉积物以及不同区域的表土磁化率进行对比,采用质量磁化率和频率磁化率探讨冰碛物的磁化率特点及其影响因素。结果表明：青藏高原东缘山地的冰碛物质量磁化率呈宽幅波动,介于（3.01~1808.80）×10-8m3.kg-1,平均值147.84×10-8m3.kg-1;频率磁化率值较低、且波动幅度小,介于0~6.89%,平均值为1.37%。不同时空条件下冰碛物的磁化率特点不同,即不同地点同一冰期磁化率的差异显著;同一地点不同冰期冰碛物的磁化率变化不明显。影响冰碛物磁化率的主导因素是母岩的岩性条件,气候因素起次要作用。Magnetic susceptibility value of the continuous sediment samples from lakes,loess and paleosol,and deep sea are widely used as an alternative indicator of environmental change.However,magnetic susceptibility measurement has yet to be involved in the research on the non-continuous deposits that reflect the climate change in a specific time period,such as the glacial deposits.This paper reports the study of the magnetic susceptibility of eight typical profiles of glacial deposits in the eastern bordering mountains of the Tibetan Plateau and the comparison of the data to those of deposits from the lake,loess,deep sea and the surface soil.Based on the mass susceptibility and frequency susceptibility data,the magnetic susceptibility of the glacial deposits is characterized and the impacting factors are analyzed.The results are as follows.（1） The magnetic susceptibilitydata of the glacial deposits in the bordering mountains to the east of the Tibetan Plateau show a large amplitude of fluctuation between 3.01×10-8 m3.kg-1and 1808.80×10-8 m3.kg-1,with a mean value of 147.84×10-8 m3.kg-1,while the frequency magnetic susceptibility values are small and fluctuated between 0 and 6.89%,with a mean value of 1.37%.（2） The temporal and spatial data of the magnetic susceptibility show different characteristics.In other words,the change of magnetic susceptibility in the different glacial stages of the same region is minimal,while the change of that in different regions of the same glacial stage is dramatic.（3） Parent rock lithology is the major factor affecting the magnetic susceptibility of the glacial deposits,while climate conditions havecomplex impact.

关 键 词：冰碛物 磁化率 气候 青藏高原 

分 类 号：P512.2[天文地球—地质学]