黑色页岩风化过程中元素的活动性及参照系的选取初探--以湖南省麻田、桃花江剖面为例

系统考察了湖南省麻田和桃花江两个不同发育程度的下寒武统黑色页岩风化剖面,并提出了元素在理想剖面中的分布模式(概念模型);通过对比分析这两个剖面中元素的分布特征与理想分布模式的关系,并结合元素相关性研究、等质量图解的判别分析、微量元素的赋存状态及地球化学性质的探讨,认为在黑色页岩风化过程中,Ti为不活动元素,可作为参照系来计算其它元素的相对迁移性,Nb、Ta的活动性较小,Zr与Hf之间存在着共迁移现象;研究表明化学风化程度是影响元素活动性的重要因素.

DISCUSSION ON ELEMENT MOBILITY AND REFERENCE FRAME SELECTION DURING BLACK SHALE WEATHERING∶EXAMPLE OF PROFILES FROM MATIAN AND TAOHUAJIANG IN HUNAN PROVINCE

We studied two Lower-Cambrian black shale weathering profiles with different maturity from Matian and Taohuajiang, Hunan Province, China, and offered an ideal model of element distribution on profiles. After comparing distribution of elements on two field profiles with that of model, we studied the correlation of elements from the two profiles. After that, we used an iso-con method to deduce element mobility. Furthermore, we discussed the influence of host phases and chemical properties on trace element mobility. All this leads to the conclusion that Ti is actually immobile and can be used as a reference frame to calculate the other element mobility , that the mobility of Nb and Ta is rather small while Zr and Hf can transport and deposit together during black shale weathering and that chemical weathering degree may influence trace element mobility.