汉江上游庹家湾剖面化学风化特征及其意义

发布时间：2019-03-15 20:07

【摘要】：通过对庹家湾黄土剖面元素的分析,揭示汉江上游地区黄土中常量元素的地球化学行为及对气候变化的响应。用XRay荧光光谱仪、MS-2型磁化率仪分别测量了庹家湾剖面元素含量及磁化率值,实验结果显示:庹家湾剖面的风成黄土化学成分以SiO_2、Al_2O_3和Fe_2O_3为主,三者含量分别为355.83 g/kg、79.62 g/kg、62.64 g/kg;以Ti为参比,Na、Ca、Mg、Si、K表现为迁移淋失,Fe、Al元素相对富集,元素的活动性及其迁移序列为NaCaMgSiKAlFe;Fe和Al元素含量曲线及CIA曲线在228~260 cm(L_1~S_1)和294~370 cm(L_1~S_2)深度处出现明显的峰值,并与磁化率曲线呈现出高度一致性,指示该层化学风化程度明显高于典型黄土,接近于古土壤(S_0),OSL年龄在27.5~21.5 ka B.P.之间。庹家湾剖面常量元素在剖面的变化,表明在汉江上游地区晚更新世末期的气候并非是持续干燥寒冷,而是存在一定的气候波动,在27.5~21.5 ka B.P.期间风化成壤作用较为明显,气候相对温暖湿润。
[Abstract]:Based on the analysis of elements in Tuojiawan loess profile, the geochemical behavior of constant elements in loess and its response to climate change in the upper reaches of Hanjiang River are revealed. The element content and magnetic susceptibility of Tuojiawan profile were measured by XRay fluorescence spectrometer and MS- 2 magnetic susceptibility meter. The experimental results show that the chemical composition of weathering loess in Tuo Jiawan profile is mainly SiO_2,Al_2O_3 and Fe_2O_3. The contents of them were 355.83 g / kg, 79.62 g / kg, 62.64 g / kg, respectively. Using Ti as a reference, Na,Ca,Mg,Si,K showed migration and leaching loss, Fe,Al element was relatively enriched, and the activity of the element and its migration sequence were NaCaMgSiKAlFe;. The content curves of Fe and Al elements and the CIA curves show obvious peaks at the depths of 228 / 260 cm (L_1~S_1) and 294 / 370 cm (L_1~S_2), and are highly consistent with the susceptibility curves. It is indicated that the chemical weathering degree of this layer is obviously higher than that of typical loess, which is close to that of paleosol (S _ (0) 0), OSL age: 27.5 ~ 21.5 ka B.P.) Between. The variation of major elements in Tuojiawan section indicates that the climate at the end of late Pleistocene in the upper reaches of Hanjiang River is not continuously dry and cold, but has some climatic fluctuation, which is in 27.5 ~ 21.5 ka B.P. During the period of weathering and soil formation, the climate is relatively warm and humid.
【作者单位】：陕西师范大学旅游与环境学院;
【基金】：国家自然科学基金项目(41271108,41371029) 国家社会科学基金项目(14BZS070) 中央高校基本科研费(GK201601006)~~
【分类号】：P512.12;P532

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