首页 | 本学科首页   官方微博 | 高级检索  
     检索      

西峰和西安黄土中盐碱化古土壤气候意义的初步探讨
引用本文:郭正堂.西峰和西安黄土中盐碱化古土壤气候意义的初步探讨[J].第四纪研究,1992,12(2):107-117,193.
作者姓名:郭正堂
作者单位:中国科学院地质研究所,法国国立农学院土壤系 中国科学院西安黄土与第四纪地质开放研究实验室
摘    要:对西峰和西安黄土剖面中古土壤的研究揭示出,作为重要气候地层标志的S4和S5古土壤竟有盐化和碱化现象。盐碱化特性直接关系到如何认识这些古土壤的气候意义。土壤化学、微形态及粘土矿物分析表明,上述古土壤以草原土特征为主,并在气候最宜期发育了森林植被。盐碱化特性并非产生于土壤被埋藏以后,而是古土壤发育末期的产物。该时期大气粉尘堆积似乎是可溶盐的来源。

关 键 词:古土壤  盐碱化  微形态  古气候

A STUDY ON THE PALEOCLIMATIC IMPLICATION OF THE SALINE-ALKALI PALEOSOLS IN XIFENG AND XI'AN LOESS SECTIONS
Institution:1. Institute of Geology, Chinese Academy of Sciences;
2. Xi'an Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences;
3. Service des Sciences du Sol, INA-PG France
Abstract:The paleosols S, and S5 in Chinese loess sequence are usually considered as climato-stratigraphic markers. Earlier studies suggested that S5 was formed under typical forest environments, representing the climatic optimum of the Quaternary. However, our pedological investigations on Xifeng and Xi'an section revealed that these soils contain abundant sodium salts. Chemical, micromorphological and clay mineralogical analys,es show that S4 and S5 have at once some characters of steppe soil (Kastanozem), forest soil (Chromic Luvisol) and salinealkali soils (Solonetz and Solonchak), which were resulted from different paleoclimatic stages. During the formation of these paleosols, steppe vegetation was dominant, but it was temporarily replaced by forest during the climatic optimum. The saline-alkali properties are closely associated with morphological features. The original spongy microstructure was considerably collapsed due to the Na+ in soils and some of the textural features in S5 are intercalated in groundmass. These phenomena are considered characteristic for natric horizons, indicating that salinization and alkalization happened when the soils were functional. Meanwhile, the strong biological activity characterized by the original spongy microstructure and the limpidity of the illuvial features indicate that saline-alkali properties were produced during the final soil-forming stage. The aeolian dust seems to be the most possible source of sodium salts. In comparison with other soils, paleosols in loess displayed thus strong particularities and high sensibility to paleoclimatic variations. Great consideration should be given to the interaction between pedogenetic and sedimentary processes. Moreover, one must be aware that (1) a pateosol was most frequently formed under changing climate, and consequently contains incompatible pedofeatures of different soll types; and (2) the passed climates under which a paleosol formed, could be considerably different from the modern climatic types, so it is difficult, even impossible to find the exact position for paleosols in the existing soil classification systems. Therefore, paleoclimatic interpretation based on strained classification of soil is usually inexact. For a ,reliable paleoclimatic interpretation, one has to identify all the single soilforming processes and interpret comprehensively their environmental conditions under which the processes operate.
Keywords:
本文献已被 CNKI 维普 等数据库收录!
点击此处可从《第四纪研究》浏览原始摘要信息
点击此处可从《第四纪研究》下载免费的PDF全文
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号