豫中黄土地区全新世黄土剖面成壤作用与古气候研究

Holocene Pedogenesis and Paleoclimate in the Loess Region in the Middle Part of the Henan Province

通过对河南豫中黄土地区黄土剖面化学元素的深入研究认为:在该地区全新世中期风化成壤过程中,Al、Fe、K、Ti、Rb、Ba等元素在古土壤中相对富集,表现出残留富集的特征;而Si、Ca、Na、Sr等元素则在风化剖面中淋失。而Al、Na在成壤过程中因具有不同的地球化学行为,从而产生显著的分异现象,并且随着成壤作用的增强分异加剧。因此,Al/Na值在黄土剖面中的变化反映了风尘堆积物成壤强度的变化,能够作为成壤作用、气候变化的替代指标。

The soil-forming process in Holocene and paleoclimate was illustrated by using the data obtained from the soil profile in the middle part of Henan Province.The magnetic susceptibility was measured on a sample of 10.0g of ground sediment with a MS-2B Magnetic Susceptibility Meter.Element contents were analyzed with a PW2403 X-ray fluorescence spectrometer.The analytical results indicated that Al,Fe,K,Ti,Rb and Ba relatively were enriched in the Paleosoil during the Holocene Climatic Optimum,while Si,Ca,Na and Sr were eluviated in the Paleosoil.The Mg was showed the feeble eluviations.However it＇s not enriched in soil.There were maximum Al/Na ratios in the periods of soil forming process of S 0 in which the intensity of pedogenesis was stronger than other time spans during the Holocene.However,there were minimum Al/Na rations in the periods of loess accumulation process of L 0,in which the intensity of pedogenesis was fainter with increasing accumulation of Aeolian dust.Therefore,the variations of Al/Na ratios in the profile indicated changes of pedogenesis intensity after Aeolian dust deposition and the Al/Na ratio was a good proxy index for reconstructing paleoclimatic change.This could be proved by relativity between Al/Na ratios and Rb/Sr ratios.