Study on Weathering Degree of Holocene Loess-paleosol Sequence in the Zhouyuan Region,Shaanxi Province

In this paper,the chemical weathering intensity and the element migration features of the LC loess-paleosol profile in the Zhouyuan region are studied in detail after analyzing the elements and their variation with XRF.Research results show that CIA value and Rb/Sr and Na/K ratios were obviously different in paleosol and loess layers.The CIA value and Rb/Sr ratio were high in paleosol layer(S0) but low in loess layer(L0),while Na/K ratio was lower in paleosol than in loess,revealing that chemical weathering of paleosol(S0) was more intensive than that of loess(L0).The chemical weathering difference between paleosol(S0) and loess(L0) was mainly caused by the distinction of climate conditions.The stronger chemical weathering in paleosol reflects that the climate was warm and humid with high eluviation during the paleosol formation.A relative enrichment of Si,K and Fe occurred during the loess formation,while Ca,Na,Mg and Ti were migrated and leached during the chemical weathering process.The migration capability of elements was in an order of Ca Na Mg Ti Al Si K Fe.Through the research of the activities of elements in the LC profile,it was found that Holocene loess in the LC profile experienced the primary process of chemical weathering characterized by leaching of Ca and Na,or just reached the secondary process characterized by leaching of K.