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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 the climatic and environmental information contained in the Xialaxiu profile in the southern part of the Three Rivers since the Middle Holocene, the types and relative contents of clay minerals in each horizon were analyzed by X-ray diffraction. The results show that the clay mineral assemblages are mainly illite, vermiculite, kaolinite and chlorite in the Xiaolaoxiu section, with montmorillonite only found in a few layers. The climate in the southern part of Sanjiangyuan is generally cold since the Mid-Holocene, and has experienced the changes of “cold dry-warm-wet-cold dry-warm wet-cold dry-more cold dry” 2 times stronger warming event. Cold-drying is conducive to the formation and preservation of soil organic carbon, which is conducive to the increase of soil organic carbon humic acid-fulvic acid ratio.