陕西五里铺黄土微量元素组成与全新世气候不稳定性研究

通过对岐山黄土剖面Pb、Cu、Zn、Cd、Mn元素含量、磁化率及粒度的研究表明，这些元素含量变化实质是气候变化的直接结果，其含量高指示风化成壤作用强烈的湿润环境，含量低指示寒冷的干旱环境，揭示出黄土高原南部全新世气候在总体温暖的情况下有明显波动变化，在5000-6000aBP出现一次明显气候干旱期，使全新世“大暖期”分裂形成两个主要的成壤期So^1和So^2。在So^1、So^2成壤时期仍存在次一级的气候变化事件，全新世时期该地区经历了黄土沉积（Lt)→古土壤发育（So^2)→黄土覆盖（Lo^2)→土壤再度发育（So^1)→黄土堆积及现代表土（Lo^1)的发展演化阶段。

Pb, Cu, Zn, Cd, Mn Elements and Climatic Change in the Loess-Paleosol Profile at Qishan, Shaanxi Province

A high resolution loess-paleosol sequence was found at Wulipu,Qishan County in Shaanxi province. Detailed studies of Pb, Cu, Zn, Cd, Mn elements content, magnetic susceptibility and grain size in the profile show that Holocene climate was not stable in the south part of the Loess Plateau. Pb, Cu, Zn, Cd, Mn contents in loess beds are lower than that in paleosols. It suggests that variation of Pb, Cu, Zn, Cd, Mn content in loess and paleosols is caused by climate change，and that can be used as climatic proxy to identify loess and paleosol layers and to reveal the monsoon climatic change. They are more sensitive than magnetic susceptibility in reflection of smaller-scale change. Higher Pb, Cu, Zn, Cd, Mn content means stronger southeast monsoon and wetter climate, lower Pb, Cu, Zn, Cd, Mn content means stronger northwest monsoon and drier climate. An aridity phase with intensive dust deposition was found between 6 000 to 5 000 a BP. The climatic evolution history of the Holocene in the south part of the loess plateau are generalized as: aeolian dust deposited to form loess Lt →paleosol S20 formed →aeolian dust deposited to form loess L20 and S20 was buried → paleosol S10 formed →aeolian dust deposited to form L10 and the formation of the modern surface soil.