青藏高原东部黄土沉积元素地球化学示踪

青藏高原东部广泛分布着典型黄土沉积，对气候变化有着敏感的响应。对青藏高原东部地区典型表土、黄土、古土壤以及砂样，进行系统的常量、微量元素组成分析，结果显示，高原东部黄土常量元素氧化物主要为SiO₂、Al₂O₃、Fe₂O₃和CaO，黄土中SiO₂和CaO含量差别较大；Rb、Sr、Ba、Zr、V含量占了微量元素含量的大部分，表土、黄土、古土壤微量元素含量差别不一。与高原东部的风沙沉积、黄土高原黄土、河西走廊黄土的对比结果表明，青藏高原东部黄土组分的常量元素之间的比值（SiO₂/Al₂O₃、TiO₂/Al₂O₃）、常量与微量元素之间的比值（Zr/Al、Zr/Ti）、常量元素三角图（Ca-Mg-K、Ca-Mg-Na）等与其他地区黄土有明显差异，而青藏高原东部黄土与高原表土沉积物及河流砂、风成砂样品比较接近。这些异同点指示青藏高原东部黄土与黄土高原黄土的物源不同；其物源可能主要来自于青藏高原内部，高原内部的河流沉积物、冰碛物等粉尘物质可能为青藏高原东部黄土的主要物源。

Geochemical Evidence for the Provenance of Loess Deposits in the Eastern Tibetan Plateau

Typical loess deposits are widely distributed in the eastern Tibetan Plateau(ETP), which are sensitive to environmental change of the Plateau region. The geochemical analyses of the surface soil, loess, paleosol samples in the ETP, show that major elements of the loess are mainly SiO₂, Al₂O₃, Fe₂O₃ and CaO, and the contents of the SiO₂ and CaO in loess vary largely. The contents of the Rb, Sr, Ba, Zr, V account mainly for the trace elemental composition of all samples, which have different characters among the surface soil, loess, paleosol. In comparison of major and trace elements of the loess with the ETP, the Chinese Loess Plateau(CLP) and the Hexi Corridor, the ratios between the major elemental oxides(SiO₂/Al₂O₃, TiO₂/Al₂O₃), the element ratios(Zr/Al, Zr/Ti), and the major elemental ternary(Ca-Mg-K, Ca-Mg-Na) show that the ETP loess are distinctly different from other regions. While ETP loess and top soil, fluvial sand, aeolian sand samples have no obvious difference. These results may indicates that the loess in the ETP has different source region against with the loess in the CLP and the Hexi corridor. We infer that the interior dry land, river drainage basin and active glacials in the Tibetan Plateau may provide the most silt materials for the loess deposit in the ETP.