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  

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

作　　者：庞奖励[1] 黄春长[1] 张占平[1] 

机构地区：[1]陕西师范大学旅游与环境学院,陕西西安710062

出　　处：《中国沙漠》2001年第2期151-156,共6页Journal of Desert Research

基　　金：国家自然科学基金项目(40071006)

摘　　要：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５０００～６０００ ａ ＢＰ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Ｓ０１和S０２。在Ｓ０１、Ｓ０２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（S２０）→黄土覆盖（Ｌ２０）→土壤再度发育（Ｓ１０）→黄土堆积及现代表土（Ｌ１０）的发展演化阶段。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 S02 formed→aeolian dust deposited to form loess L02 and S02 was buried → paleosol S01 formed→aeolian dust deposited to form L01 and the formation of the modern surface soil.

关 键 词：全新世 黄土-古土壤 微量元素 陕西 古气候 磁化率 粒度 

分 类 号：P642.131[天文地球—工程地质学] P532[天文地球—地质矿产勘探]