江西九江红土堆积的粒度特征及成因研究  

AEOLIAN ORIGIN OF THE RED EARTH TORMATION IN JIUJIANG CITY OF JIANGXI PROVINCE,CHINA: EVIDENCE FROM GRAIN-SIZE ANALYSIS

作　　者：李敬卫[1] 乔彦松[1,2] 王燕[1,2] 彭莎莎[1,3] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]国土资源部新构造运动与地质灾害重点实验室,北京100081 [3]中国海洋大学海洋地球科学学院,山东青岛266003

出　　处：《地质力学学报》2009年第1期95-104,共10页Journal of Geomechanics

基　　金：国家自然科学基金资助项目(40472088);中国地质调查局地质调查项目(1212010741403);地质力学研究所基本科研业务费项目(DZLXJK200711)

摘　　要：在南方红土的研究中,区分不同地区红土地层的成因类型是研究区域古环境演化的关键。以江西九江红土剖面为例,通过系统的粒度分析,并与西峰黄土、古土壤样品及代表性河、湖相沉积的粒度特征进行对比,结果表明,九江红土与西峰黄土、古土壤样品具有相似的粒度分布特征,而与河、湖相沉积有较大区别。其中,九江剖面上部的下蜀土与西峰黄土粒度特征相近,而剖面下部的网纹红土与西峰古土壤样品更为相似,表明江西九江红土堆积与中国北方黄土一样属于风尘堆积。研究成果为古环境信息的进一步提取奠定了基础。The Red Earth Formation in the middle-lower Yangtze River is an important pedo- stratigraphical unit in southern China. This formation is among the best geological records of Quaternary environment that bear information of climate changes for the subtropical zone of China. The study on the origin of this formation is the basis for further investigation of the paleoclimatic information. In this study, grain-size was analyzed on the samples from Jiujiang section at Jiujiang city of Jiangxi Province, and the result was compared with that of the typical Quaternary eolian deposit, as well as the lacustrine and fluvial sediments. Grain-size distribution was determined with a Malvern Mastersizer 2000 particle analyzer with a precision less than 1%. The analysis on grain-size indicates that the Xiashu loess and vermiculated red soil （VRS） in Jiujiang section consist of uniform fine particles. The particles display a bimodal distribution, with grain-size fraction of 5 - 50 μm dominantly, and 〉 63μm in a small part. The distribution is essentially similar to that in the Xifeng loess samples, but differ from the multimodal patterns of the lacustrine and fluvial deposits. The Xiashu loess and VRS are also similar to the Xifeng loess samples in grain-size parameter. The mean grain-sizes of the Xiashu loess and VRS are about 6.4 -- 6.8Ф （9.0 - 11.8μm） and 7.1 - 7.2Ф （6.8 - 7.3μm） respectively, somewhat finer than those of the Xifeng loess samples. The Xiashu loess, VRS and Xifeng loess have a smaller mean square deviation value than the fluvial samples, indicating a much better sorting and relatively stable depositional dynamics. The Xiashu loess, VRS and Xifeng loess samples show a positive skewness, but the fluvial samples a negative one. The lacustrine samples also show a positive, but obviously larger skewness. In kurtosis value, the Xiashu loess and VRS samples are close to the Xifeng loess, and the fluvial sediments are obviously smaller than the lacustrine samples. All these indieate that the Red Ear

关 键 词：江西九江 网纹红土 下蜀土 粒度特征 成因 

分 类 号：P534.63[天文地球—第四纪地质学]