| 贵阳乌当石炭系底部古风化壳地球化学特征及古环境意义 |
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| 作者姓名： | 张英帅 毛家仁 王启林 肖宇 王甘露 |
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| 作者单位： | 贵州大学资源与环境工程学院,贵阳 550025 |
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| 基金项目： | 贵州省地质勘查基金“页岩气开发建设对区域水资源的需求及其影响评估(编号: 黔国土资发[2013]64号)”和贵州大学“大学生SRT计划(编号: 贵大SRT字[2015]22号)”项目联合资助 |
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| 摘 要： | 在贵阳乌当小关口剖面石炭纪祥摆组底部发现了一套保存较好的碳酸盐岩古风化壳。野外地质调查与室内综合研究表明: 该套古风化壳岩性主要为灰绿色、砖红色铁质高岭石黏土岩和粉砂质黏土岩夹褐铁矿层; 古风化壳主量元素氧化物Al2O3、TiO2和Fe2O3富集,SiO2轻微淋滤, CaO、MgO、Na2O和K2O强烈淋滤; 微量元素Sc、V、Cr、Cu、Zn、Ga、Ba、Th和Pb等均相对富集,Sr、Mn等易溶元素淋失; Sr/Cu、A/NK、A/CNK、OI、CIA等多项指数均指示该套古风化壳形成于风化强烈、炎热潮湿的热带-亚热带古气候条件之下。根据古风化壳的稳定性及原岩岩性特征,推断该套古风化壳形成时,研究区内广泛发育溶丘、溶洼等古岩溶地貌。
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| 关 键 词： | 古风化壳 地球化学 古气候 古环境 乌当地区 |
| 收稿时间： | 2017-08-22 |
Geochemical characteristics and palaeoenvironmental significance of the paleo-weathered crust at the Carboniferous bottom in Wudang of Guiyang |
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| Authors: | ZHANG Yingshuai MAO Jiaren WANG Qilin XIAO Yu WANG Ganlu |
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| Institution: | Resources and Environmental Engineering College, Guizhou University, Guiyang 550025, China |
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| Abstract: | A well-preserved paleo-weathered crust of carbonate rocks is found at the bottom of Carboniferous Xiangbai Formation at Xiaoguankou Section of Wudang, Guiyang. Based on field observation and indoor comprehensive research, it can be referred that the paleo-weathered crust is mainly composed of grey-green or brick-red ferrous kaolinite claystone and limonite-bearing silty claystone. Al2O3, TiO2 and Fe2O3 as the major elements are rich in the paleo-weathered crust. SiO2 is leached slightly, but K2O, Na2O, CaO and MgO are leached seriously. Trace elements, including Sc, V, Cr, Cu, Zn, Ga, Ba, Th and Pb, are relatively enriched, and Sr, Mn as the soluble elements are leached. The indexes, including Sr/Cu, A/NK, A/CNK, OI and CIA, all indicate that the paleo-weathered crust should be formed under the tropical to subtropical paleoclimate conditions of strong weathering, torridity and humidity. In addition, due to the stability of the paleo-weathered crust and the lithological characteristics of parent-rock, the authors inferred that ancient karst landform including karst depression and highland had been widely developed during the formation of paleo-weathered crust. |
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| Keywords: | paleo-weathered crust geochemistry paleoclimate paleoenvironment Wudang area |
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