临汾盆地黄土沉积微量元素地球化学特征及其气候意义

Geochemical characteristics and climatic significance of trace elements in loess of Linfen basin

以临汾盆地黄土为研究对象,对其微量元素地球化学特征进行分析。选取黄土剖面中Li、Cr、Zn、Mn、Ge、Ga、Co、Rb和Sr 9种微量元素并结合黄土磁化率、色度及平均粒径进行研究,结果表明:Li、Zn、Mn、Ge、Ga、Co、Rb在古土壤层和弱古土壤层(S_(1)、L_(1)S_(1))含量高,在黄土层(L_(1)L_(1))含量较低,微量元素动态特征与磁化率、色度等指标反映的气候变化一致,在古土壤形成时期气候温暖湿润,成壤作用强,期间冷暖波动频繁;黄土堆积时期气候干冷,降水较少,成壤作用较弱;弱古土壤形成时期气候稍有回暖的气候变化记录;黄土-古土壤中Rb/Sr对气候变化的反应比磁化率和色度更加明显,可作为临汾盆地气候变化替代指标。

Taking the loess of Linfen basin as the research object,the geochemical characteristics of nine trace elements Li,Cr,Zn,Mn,Ge,Ga,Co,Rb and Sr in the loess profile were analyzed combined with the magnetic susceptibility,chroma and grain size indexes of the sediments.The results showed that the contents of Li,Zn,Mn,Ge,Ga,Co and Rb are higher in the paleosol layer and weak paleosol layer,and lower in the loess layer.The dynamic characteristics of trace elements are consistent with the climate change reflected by the indexes such as magnetic susceptibility and chroma.During the formation of paleosol,the climate was warm and humid,and the soil formation was strong,and the cold and warm fluctuations were frequent.During the loess accumulation period,the climate was dry and cold with less precipitation and weak soil formation,and climate in weak paleosol formation period showed slightly warming records.The response of Rb/Sr in loess-paleosol to climate change is more obvious than that of magnetic susceptibility and chroma,which can be used as an alternative indicator of climate change in Linfen basin.