Origin, weathering, and geochemical composition of loess in southwestern Hungary
Origin, weathering, and geochemical composition of loess in southwestern Hungary
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DOI：
10.1016/j.yqres.2008.02.001
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发表时间：
2008-05
影响因子：
2.3
通讯作者：
G. Újvári;A. Varga;Z. Balogh‐Brunstad
中科院分区：
文献类型：
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作者：
G. Újvári;A. Varga;Z. Balogh‐Brunstad
黄土地球化学一般反映古风化条件，可用于确定上陆壳的平均成分。本研究对匈牙利西南部黄土样品进行了主要元素和微量元素浓度分析，确定了影响其化学组成的因素，并提出了新的平均黄土组成。所有研究的黄土样品的化学成分几乎一致，表明这些沉积物的蚀变历史相似。化学蚀变指数（Chemical Index of蚀变）值（58 ~ 69）表明长英质烃源区风化程度为弱至中等。Al2O3-CaO + Na2O-K2O模式表现出典型的非稳态风化条件，表明更新世阿尔卑斯-喀尔巴阡体系的构造活动。全岩元素收支受长英质岩浆岩或改造过的沉积物源的重矿物控制。地球化学参数表明，在河流和风成过程中，沙尘颗粒被回收并均匀化。
Loess geochemistry generally reflects paleo-weathering conditions and it can be used to determine the average composition of the upper continental crust (UCC). In this study, major and trace element concentrations were analyzed on loess samples from southwestern Hungary to determine the factors influencing their chemical compositions and to propose new average loess compositions. All studied loess samples had nearly uniform chemical composition, suggesting similar alteration history of these deposits. Chemical Index of Alteration values (58–69) suggested a weak to moderate degree of weathering in a felsic source area. Typical non-steady state weathering conditions were shown on the Al2O3–CaO+Na2O–K2O patterns, indicating active tectonism of the Alpine–Carpathian system during the Pleistocene. Whole-rock element budgets were controlled by heavy minerals derived from a felsic magmatic or reworked sedimentary provenance. Geochemical parameters indicated that dust particles must have been recycled and well homogenized during fluvial and eolian transport processes.