汾渭盆地全新世成壤环境演变比较研究

通过对汾渭盆地全新世土壤的野外考察以及磁化率和高分辨率CaCO3 的分析 ,揭示了该区域土壤成壤过程与气候变化关系。研究表明 ,汾渭盆地全新世的S0 地层形成于全球性的全新世气候最适宜期 ,约从 85 0 0aBP土壤开始发育 ,形成较厚的S0 层。约从 310 0aBP起始 ,气候发生变化 ,干旱和沙尘堆积形成了黄土L0 层和现代表土层。土壤剖面磁化率与CaCO3 指标反映 ,由于地带性因素存在 ,全新世汾河盆地古土壤S0 的成壤强度远远低于渭河盆地。在全新世气候最适宜期 ,两地气候和环境的差异扩大 ,而晚更新世马兰黄土堆积期间和全新世其它主要阶段 ,两地气候和环境的差异相对减小。

Comparative Study of the Holocene Soil-formation Environmental Evolution in the Weihe and Fenhe Basins

The Weihe and Fenhe basins are located in the middle reaches of Yellow River, the period of sediment series of the Quaternary loess-paleosol is long, the sediment is continuous, especially the Holocene sediment series is peculiar, and it is an ideal information carrier for researching global climate change. In this paper, the relationship between the regional soil-formation process and the climate change is revealed based on the field investigation of the Holocene soils and the analysis of the magnetic susceptibility and the content of CaCO 3 in the Weihe and Fenhe basins. The results reveal that the Holocene S 0 stratum of paleosol in the Weihe and Fenhe basins was formed during the Holocene climatic optimum. The soil began to develop from the early Holocene Epoch about 8 500 a B.P., and the thick S 0 stratum was formed. The climate began to deteriorate around 3 100 a B.P., and the loess L 0 stratum and modern topsoil layer are formed under droughts and dust sediment. The magnetic susceptibility and the content of CaCO 3 recorded by the soil profiles reveal that the Holocene soil-formation intensity of the paleosol S 0 in the Fenhe Basin was much lower than that in the Weihe Basin due to the existence of the zonal factors. During the Holocene climatic optimum, the climatic and environmental differences between these two basins were high. The recent loess L 0 and its topsoil were buried by soil S 0. The data of the magnetic susceptibility and the content of CaCO 3 reflect that the Holocene paleosol S 0 in the Weihe basin was much more matured than that in the Fenhe basin.