干旱区地理2011，Vol.34Issue(5)：733-738,6.
青藏高原东北缘拉脊山南坡黄土剖面的土壤发育特征
Soil development characteristics of a loess profile on south slope of Laji Mountain, northeastern Tibetan Plateau
摘要
Abstract
The northeastern margin of the Tibetan Plateau (TP) holds an important location where the Westerly, the East Asian and Indian Monsoon current join, thus it is sensitive to regional and global climates. As a major carbon reservoir, the organic matter of soil in the Tibetan Plateau is of great significance to global carbon fixation with ca. 23.44% of China carbon storage and ca. 2.4% of global. This paper presents a multi-proxy study of a loess -paleosol profile, located on the south slope of the Laji Mountain, northeastern margin of the Tibetan Plateau. Soil development indices of both modern soil and paleosol layers of the profile were obtained through physical and geo-chemical analyses (e.g. Grain-size, organic matter, carbonate contents, element concentrations and clay minerals), in order to distinguish their origin of parent material of loess in the study area and to discuss their environmental implications. The results indicate (1) that the loess on the south slope of the Laji Mountain is characterized by relatively high clays, low silt and CaCO3 contents with relative to its counterparts in the loess profile and adjacent basins around Lake Qinghai and (2) that clayish loess is its parent material of the paleosol layer. In contrary, loess as the partent material for modern soil layer is much coarser. These differences reflect the divergences in origins of parent material of soil layers, namely the paleosol has been developed by loess deposited on subduction zone, while loess for modern soil was deposited on accumulation zone. (3 ) The clay mineral assemblage of the studied profile is basically kaolinite + illite + vermiculite, which is different from the illite + montmorillonite + kaolinite pattern on the Loess Plateau, implying a cooler and drier climate condition. (4) The chemical weathering intensity as presented by ba value, Rb/Sr ratios, CaCO3 contents, illite/kaolinite ratio and crystallinity index of illite shows an increasing tendency upwardly, indicating a gradual transition from cold-dry to relatively warm-humid climate dominance at the Laji Mountain area. (5) For both the palesol and the modern soil layers, the soil development index ( SI) also exhibits an increasing tendency upwardly, indicating that although the cold-dry climate prevailed at the Laji Mountain area, relatively stronger pedogenesis still occurred on the loess. The physical and geo-chemical indices of the studied soil profile on the south slope of the Laji Mountain, northeastern margin of the TP would helpful for better understanding the mechanism of soil formation and the accumulation rate under different climatic conditions, and also helpful for the sustainable development of agriculture in the study area.关键词
土壤/发育特征/黄土/母质来源/拉脊山/青藏高原Key words
soil/Loess/parent material/Laji Mountain/Tibetan Plateau分类
农业科技引用本文复制引用
张琳,李福春,吴枫,罗旭鹏,孙千里,金章东..青藏高原东北缘拉脊山南坡黄土剖面的土壤发育特征[J].干旱区地理,2011,34(5):733-738,6.基金项目
国家科技支撑计划项目(编号:2007BAC30B05) （编号:2007BAC30B05）
