渭河上游地区樊家城黄土-古土壤剖面Rb、Sr、Ba存留特征及意义

选择渭河上游樊家城全新世黄土-古土壤剖面为研究对象，对该剖面元素Rb、Sr、Ba含量和磁化率、粒度、CaCO₃进行了测定。结果表明：Rb、Sr、Ba含量及Rb/Sr、Ba/Sr比值与磁化率、粒度、CaCO₃含量显著相关，能够指示渭河上游地区全新世的气候变化。剖面中古土壤层的磁化率、黏粒、Rb/Sr、Ba/Sr以及元素Rb、Ba含量高于黄土层，CaCO₃、Sr含量小于黄土层，指示渭河上游地区古土壤层（S₀）形成时期主要受夏季风影响，气候温暖湿润，淋溶作用强，风化成壤作用强；而黄土层形成时期主要受冬季风影响，气候相对冷干，淋溶作用弱，风化成壤作用弱。在全新世中期，古土壤层S₀¹与S₀²之间的黄土夹层，反映了渭河上游地区在全新世大暖期的6 000~5 000 a BP期间气候显著恶化。

Composition Characteristics and Significance of Rb,Sr and Ba of Fanjiacheng Loess-paleosol Profile in the Upper Reaches of the Weihe River

The Holocene loess-paleosol profile of Fanjiacheng in the upper Weihe River was selected as the research object, and the contents of Rb, Sr, Ba, magnetic susceptibility, grain size and CaCO₃ in the profile were measured. The results show that Rb, Sr, Ba and Rb/Sr ratio, Ba/Sr ratio are significantly correlated with magnetic susceptibility, particle size and CaCO₃, which can indicate the Holocene climate change in the upper Weihe River. The magnetic susceptibility, clay, Rb/Sr, Ba/Sr ratio and elements Rb and Ba in the paleosol layer in the profile are higher than those in the loess layer, while the contents of CaCO₃ and Sr are lower than those in the loess layer, suggesting that the paleosol layer (S₀) in the upper Weihe River was mainly affected by summer monsoon, with a warm and humid climate, and it further indicated the leaching degree, weathering and pedogenesis were strong. The formation period of loess layer was mainly affected by winter monsoon, with a relatively cold and dry climate, and it further indicated the leaching degree, weathering and pedogenesis were weak. The loess interlayer between the paleosol layers S₀¹ and S₀² reflected the significant deterioration of climate in the upper Weihe River during the period of 6 000-5 000 a BP in the mid-Holocene.