青藏高原三江源南部下拉秀剖面粘土矿物组合特征及其环境意义

Characteristics and Environmental Significance of Clay Minerals Composition of Xialaxiu Profile in Three Rivers Source Southern,Qinghai-Tibet Plateau

为揭示中全新世以来三江源南部下拉秀剖面蕴含的气候环境信息,利用X衍射方法分析了剖面各层位粘土矿物类型及其相对含量。结果表明:下拉秀剖面粘土矿物组合以伊利石为主,蛭石次之,高岭石与绿泥石含量相当,蒙脱石最少仅见于少数层位。三江源南部中全新世以来气候总体寒冷,历经了"冷干—暖湿—冷干—暖湿—冷干—更加冷干"的变化过程,在6.0ka B.P.和5.5ka B.P.前后发生了2次较强的变暖事件。冷干有利于土壤有机碳的形成与保存,有利于土壤有机碳胡敏酸富里酸比值的提高。

In order to reveal climate information of Xialaxiu profile in Three Rivers source southern,clay mineral types and their relative content was analyzed with X-ray diffraction method.Results showed that clay mineral composition of Xialaxiu profile was mainly illite,vermiculite less,kaolinite and chlorite quite content and,montmorillonite least found only in a small number of layers.Since Middle Holocene climate was generally cold in Three Rivers source southern experienced a＂cold and dry-warm and wet-cold and dry-warm and wet-cold and dry-more cold and dry＂change process.Two strong warming events occurred in 5.5ka B.P.and 6.0ka B.P..Cold dry climate was conducive to the formation and preservation of soil organic carbon,which was conducive to the raise of the ratio of humic acid and fulvic acid.