陕西扶风黄土台塬全新世成壤环境变化研究

通过对陕西扶风全新世黄土剖面的土壤学和地层学研究、磁化率、酸碱度和粒度测定分析, 揭示了周原地区全新世成壤环境演变过程。黄土剖面中的埋藏古土壤S₀形成于全新世大暖期的温湿环境中, 古土壤S₀中黄土夹层(L_x)的存在, 表明6000aBP前后季风气候发生转折, 在6000~5000aBP出现一个干旱阶段, 并使得全新世大暖期分裂成为两个主要的温湿阶段。大约从3100aBP开始, 受全球降温过程的影响, 季风气候朝向干旱化方向发展, 全新世大暖期的成壤作用被黄土堆积所取代。现代表土大约从1500aBP开始发育。

Holocene Pedogensis and Environmental Change on the Loess Tableland in Fufeng County, Shaanxi Province

The integrative pedological and sedimentary study was carried out in a Holocene loess profiles on the Zhouyuan loess tableland in Fufeng County, Shaanxi Province. The field investigation and the measurement of magnetic susceptibility, pH values and grain-size distribution has reveled the variations of the pedological environment during the last 11 500 years. Corresponding to the Holocene climatic optimum (8 500~3 100 a BP), Paleosol S₀ was developed. The analytical results indicate that this soil is a soil complex. There was an arid phase (6 000~5 000 a BP) represented in the middle of the Holocene climatic optimum, during which a loess bed (L_x) was deposited. Therefore, the Holocene palaeosol S₀ becomes two separated soils (S₀² and S₀²)in this profile. It also shows that the period between 8 500 a BP and 6 000 a BP was the maxmum of the Holocene climatic optimum. From 3 100 a BP when the pre-dynastic Zhou people lived and built their Capital city "Qiyi" on the Zhouyuan loess tableland, the Holocene climatic optimum was ended and the monsoon climatic became colder-drier. The recent loess (L₀) was accumulated. This is a widespread phenomenon over the Loess Plateau. The modern soil (MS) has been developed since about 1 500 a BP due to the disturbance of cultivation, the modern soil has been well developed in this profile.