关中平原全新世土壤与环境研究

Holocene Soil Clay Grouting Characteristics and Enviormental Significance in Guanzhong Plain

根据蓝田田家村、长安四府村、西安吴家坟和岐山雍川村剖面样品的粒度分析、CaCO3含量测定和微结构的鉴定资料得知,关中平原全新世中期形成的土壤S0具有明显的淀积粘化特征和现代沉积间断条件下发育的土壤剖面特点,该层土壤的构成物质至少有一部分是由先前形成的黄土经成壤作用改造而成的。关中平原S0的粘化类型不仅可以指示当地温湿的气候环境和很少有沙尘暴活动,而且它与西北荒漠区全新世千年尺度上的环境变化存在遥相关关系。全新世晚期发育的黄土L0是在相对冷干条件下形成的狭义土壤,它具有明显的残积粘化和残积—淀积粘化特征,它发育在沙尘暴连续堆积的条件下,形成了厚度大发育弱的粘化层和厚度大而均匀分布的CaCO3淀积层。全新世黄土剖面特征显示,在风尘连续堆积条件下发育的土壤可以不具有明显的剖面分层,厚度可以大于2m。关中平原全新世L0发育时的气候与西北荒漠区的气候也存在遥相关关系。

on the basis of materials grain size analysis, CaCO3 content and microstructure determination of the soil sample from Tianjia village profile in Lantian, Sifu village profile in Chang＇an and Yongehuan profile in Qishan, we know that the soil S0 developed in the middle Holocene had obvious illuvial clay grouting characteristics. The S0 has the typical characteristics of soil profile under the recent depositional break hiatus. At least, a part of its parent matter was mainly from L1 which was reconstructed by the soil- forming action. The S0 clay grouting type in Guanzhong Plain not only to be possible to indicate the characteristics of local biological climate environment and little activity of sand-dust storm, but also to indicate the remote correlation of environmental variation in thousand scale between this area and the northwest desert area. But the L0 developed in the later Holocene was soil in narrow sense and had the obvious sedentary grouting characteristics or sedentary-illuvial clay grouting characteristics, it developed in the process of continuous sediment of sand-dust storm, and formed the thick clay grouting layer which developed weakly, the thick CaCO3 illuvial layer which distributed evenly. The profdile characteristics of the Holocene L0 indicate that soils developed under continuous deposit process of sand-dust storm, there are no obvious horizons in the soil profile and soil thickness can be much larger than 2 m. There was the remote correlation of the climate between Guanzhong Plain and the northwest desert area during development of L0.