| 陇东新近纪红粘土与第四纪黄土地球化学特征及其物源和风化指示意义 |
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| 引用本文： | 綦琳,乔彦松,刘宗秀,王燕,彭莎莎.陇东新近纪红粘土与第四纪黄土地球化学特征及其物源和风化指示意义[J].地质力学学报,2021,27(3):475-490. |
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| 作者姓名： | 綦琳 乔彦松 刘宗秀 王燕 彭莎莎 |
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| 作者单位： | 1.中国地质科学院地质力学研究所, 北京 100081 |
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| 基金项目： | 国家自然科学基金项目（41907377，41888101，41772383） |
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| 摘 要： | 甘肃省平凉市灵台县邵寨镇剖面风尘堆积底界年龄大约为5.23 Ma B.P.，通过对该剖面新近纪红粘土与第四纪黄土-古土壤序列的常量元素、微量元素、Nd同位素的测试，分析其在物源和风化方面的指示意义，发现新近纪红粘土与第四纪黄土具有相似的常量、微量元素UCC标准化曲线和稀土元素球粒陨石标准化曲线，指示二者皆来自广阔的物源区，经过了相似的搬运过程，并在搬运中得到充分混合。新近纪红粘土的MgO、Li、Cs、Bi含量较高，Na2O、稀土元素La-Lu、Y含量较低。风化参数Na2O/Al2O3、化学风化参数CIA以及Al2O3-CaO+Na2O-K2O (A-CN-K)图，均显示新近纪红粘土比第四纪黄土经历了更为强烈的风化过程。新近纪红粘土的稳定元素比值(TiO2/Al2O3，SiO2/Al2O3，SiO2/TiO2，Zr/Hf，Nb/Ta，Lu/Hf，Y/Ho，Th/Nb和Hf/Nb)、稀土元素总量、轻稀土与重稀土的分异程度、轻稀土内部分异程度、重稀土内部分异程度、Ce和Eu的异常程度、同位素εNd(0) 值等，皆与第四纪黄土无太大差异，指示二者物质来源一致。粒度以及风化强度的差异，可能是导致新近纪红粘土与第四纪黄土常量和微量元素含量差异的主要原因。
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| 关 键 词： | 风尘堆积 红粘土 地球化学 物源 黄土高原 |
| 收稿时间： | 2020/12/1 0:00:00 |
| 修稿时间： | 2021/2/11 0:00:00 |
Geochemical characteristics of the Tertiary and Quaternary eolian deposits in eastern Gansu province: Implications for provenance and weathering intensity |
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| QI Lin,QIAO Yansong,LIU Zongxiu,WANG Yan,PENG Shasha.Geochemical characteristics of the Tertiary and Quaternary eolian deposits in eastern Gansu province: Implications for provenance and weathering intensity[J].Journal of Geomechanics,2021,27(3):475-490. |
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| Authors: | QI Lin QIAO Yansong LIU Zongxiu WANG Yan PENG Shasha |
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| Institution: | 1.Chinese Academy of Geological Sciences, Beijing 100081, China2.Key Laboratory of Neotectonic Movement and Geohazard, Institute of Geomechanics, Beijing 100081, China3.Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, Guangdong, China4.Research Center of Neotectonism and Crustal Stability, China Geological Survey, Beijing 100081, China |
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| Abstract: | An eolian deposit section named Shaozhai, which has been developed since the Tertiary in eastern Gansu province, was analyzed for major-trace elements and Sm-Nd isotopic compositions to explore the relationship for the provenance and weathering intensity between the Tertiary red clay and Quaternary loess. The magnetostratigraphy data indicates that the basal age of the typical eolian deposits is about 5.23 Ma B.P.. We observed both similarities and obvious differences in the Tertiary red clay and Quaternary loess. Specifically, the Tertiary red clay has similar UCC-normalized major-trace element abundances and chondrite-normalized rare earth element abundances as the Quaternary loess, demonstrating that dust materials making up these sediments likely have experienced similar and numerous recycling processes prior to deposition. The Tertiary red clay has relatively high abundances of MgO, Li, Cs, Bi and low abundances of Na2O, La-Lu, Y. In comparison with the Quaternary loess, chemical weathering parameters such as Na2O/Al2O3, CIA, combined with the A-CN-K diagram suggest that the Tertiary Red clay has experienced a stronger weathering intensity. There is not much difference in the TiO2/Al2O3, SiO2/Al2O3, SiO2/TiO2, Zr/Hf, Nb/Ta, Lu/Hf, Y/Ho, Th/Nb, Hf/Nb, total rare earth elements, differentiation degree between the light and heavy rare earth element, internal differentiation degree of the light rare earth element, abnormal degree of Ce and Eu, εNd(0) of the Tertiary red clay and Quaternary loess, demonstrating a similar provenance for them. The finer grain size and stronger weathering of the Tertiary red clay may be responsible for the difference in major and trace element content for the Tertiary red clay and Quaternary loess. |
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| Keywords: | eolian deposits red clay geochemistry provenance Chinese Loess Plateau |
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