论南极多年冻土区的化学风化作用——以中国长城站、澳大利亚凯西站和戴维斯站地区为例

通过研究寒冻化学风化作用下的元素地球化学性状,包括化学元素的相关性分析,元素的集散特征,稀土元素的分布模式以及粒级对元素迁移的影响,粘土矿物对痕量元素的吸附作用等,得出不同地区风化壳的类型:长城站地区(西南极亚南极地区)形成碳酸盐层状风化壳;戴维斯站所在的维斯特福尔德丘陵区基岩上发育了弱风化碎屑的碳酸盐裂隙型风化壳;在凯西站地区,基岩的寒冻风化过程尚未进入最低风化度形成的碳酸钙壳阶段,而是完全处于风化最初始的碎屑型阶段.

CHEMICAL WEATHERING IN PERMAFROST REGIONS OFANTARCTICA——GREAT WALL STATION. CASEY STATION AND DAVIS STATION AREAS

Although it is cold and dry in permafrost region of Antarctica, chemical weathering and ion migration do occur. CaCO3 is leached downwards and deposited at a depth of about 1m in Great Wall Station area. Chemical weathering is stonger in the Great Wall Station area then in the Casey and Davis areas. This paper deals with the chemical weathering process of bed rocks in some areas of Antarctica. The samples were collected from the areas of the Great Wall Station of China by Xie Youyu and Zhan Qingsong in 1984 to 1986, Casey station by Xie Zichu in 1984 and the Davis station by Zhang Qingsong in 1980. We have known that types of weathering crust in different rareas by correlation analysis of the chemical elements, the characteristics of enrichemnt and migration of the elements in weathering process, the influence of grain size on element migration and clay minerals and the absorption of rare elements. (1) Great Wall Station area. According to the analysis of aggregation and dissemination of elements, it is known that some elements change from bottom upwards, such as the cation exchange capacity, which is a best indicator reflecting weathering intensity; contents of K, Na, Ca, and Mg all had dispersed during the weathering process, but Co, Ti, Fe and Mn are all concentrated upward. The content of CaCO3 is high at a certain depth. As mentioned above, an obvious differentiation of elements occurred in the weathering crust of volcanic andesite-basaltic agglomerate and tuff in this area. It appears that there is a stratified weathering crust type and can be named the carbonate-stratified weathering crust. (2) Davis Station Area. The distribution and migration of elements indicate that the chemical weathering process does occur in such a polar area, although it is rather weak and an initial stage, there is a tendency that the debris weathering crust is changing to the silica-alminium-chloride type. The weathering crust there can be termed the debris-carbonate type of weakly weathering crust. (3) Casey Station Area.There is no any secondary CACO3 in sediments and the weathering crust in Casey Station area. The content of soluble salt is also very low, 0.03 to 0.11% in salinity. It can be concluded that this area is still in an initial stage of weathering with a debris type of weathering crust.