湘西下寒武统黑色页岩风化元素活动规律  

Regularity of Element Mobility in the Weathering of Lower Cambrian Black Shales in Western Hunan Province,China

作　　者：杨梓璇 彭渤 徐婧喆 方小红 曾等志 肖瑶 谢伟城 

机构地区：[1]湖南师范大学资源与环境科学学院,环境重金属污染机理与生态修复重点实验室,长沙410081 [2]张家口学院理学系,河北张家口075000

出　　处：《矿物岩石地球化学通报》2017年第6期984-994,共11页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41073095,40572172);湖南省高校科技创新团队支持计划项目(2014)

摘　　要：为探讨黑色页岩风化过程中的元素活动规律,采集了湘西东坪、柑子坪下寒武统黑色页岩风化-成土剖面的样品进行了主、微量元素地球化学分析。结果表明,两剖面风化层有不同的主量元素组成,但其土壤层的主量元素组成相对均一。主量元素Si、K、Na、P等在风化过程中活泼而被淋滤释出;而Al、Fe、Mg等元素既可被淋滤释出,又可产生次生富集。而成土过程中,所有主量元素都表现被淋出的特征。元素Mn的次生富集明显;重金属V、Ni、Cu、Cr、Co、Zn、Pb等在风化-成土过程中的化学活性与Al、Fe等主量元素相似;亲石元素Sc、Rb、Sr、Cs、Ba、Th、U、Ga、Ge等在风化-成土过程中的活性较强,趋于被淋出,且其淋滤释出率随风化程度增强而升高;高强场元素Zr、Hf、Nb、Ta等的化学活性相对稳定。In order to discuss regularity of element mobility in the weathering process of black shales, we have analyzed major and trace elements of Lower Cambrian black shales collected from Dongping and Ganziping weathering profiles in western Hunan province, China. The results show that major element compositions of weathered rocks from the two profiles are significantly variable, whereas those of soils developed at these profiles are relatively homogeneous. Major elements of Si, K, Na, and P were leached out from the weathered black shale due to their mobilities in weathering process, whereas elements of A1, Fe and Mg could be leached out from the upper part of the weathered black shale and then secondary re- enriched in the lower part of the weathered black shale. However, major elements were leached in the soil formation process with exception of the obvious secondary enrichment of the element Mn. Heavy metal elements of V, Ni, Cu, Cr, Co, Zn and Pb display similar mobility feature to elements of A1 and Fe in both the shale weathering and soil formation processes. The lithophile elements of Se, Rb, St, Cs, Ba, Th, U, Ga and Ge are tended to be leached due to their mob- ilities in both shale weathering and soil formation processes, with their leaching release rates are increased with the stron- ger weathering. However, high field-strength elements of Zr, Nb, Hf and Ta were mostly immobile in both the shale weathering and soil formation processes.

关 键 词：黑色页岩风化 元素活动规律 主量元素 微量元素 下寒武统黑色页岩 

分 类 号：P512.1[天文地球—地质学]