摘要
安徽宣城向阳剖面高分辨率粒度分析结果表明 :1)网纹红土含有较高的胶结性很强的次生氧化铁 ,样品前处理时单颗粒的分散效果将会显著地影响粒度测试结果。向阳剖面不含 >2mm的砾石 ,砂粒 ( >6 3μm)的含量也很低 ,粘粒 ( <2 μm)和粗粉砂 ( 10～ 5 0 μm)明显富集 ;2 )除底部外 ,向阳剖面粒度组成特征反映了明显的风成特性 ,但不能因此忽视其强风化特征的存在 ,尤其是剖面中、下部的网纹红土。应肯定向阳网纹红土的风成特性 ,但不能简单地称其为风积成因 ;3)向阳剖面磁化率值与粘粒和细颗粒含量无显著正相关性 ,说明磁化率值不能指示网纹红土的风化强度 ;4 )向阳剖面粒度分布特征无法提供该剖面存在多个“沉积—成土”过程旋回的证据。向阳网纹红土更多地体现了其具有原始风成沉积和后期强烈风化的双重特性。
Grain size distribution of the reticulate red clay of the Xiangyang section in Xuancheng, Anhui Province was measured in high resolution. The results are as follows: (1) The effect of grain dispersion during the pre treatment would significantly affect the result of measurement as the reticulate red clay contains high content of secondary iron oxides with strong cementation. The reticulate red clay of the section contains no gravel (>2mm); low content of sand (>63μm); and high content of both clay (<2μm) and coarse silt fraction (10～50μm). (2) Except for the bottom layer, the grain size distribution of the reticulate red clay in the Xiangyang section indicates its aeolian characteristics. However, its strong weathering degree should never be neglected, especially in the reticulate layer of the section. Here, we could only determine some aeolian characteristics of the reticulate clay, rather than the typical wind blown formation of it. (3) There is no significant positive correlation between magnetic susceptibility (MS) values and clay fraction contents, indicating the MS values are not controlled by the weathering degree of the reticulate red clay. (4) The grain size distribution could not prove the existence of multiple cycles of depositional alternating with pedogenic proeesses in the section. The section mostly reflects its double features of both aeolian characteristics and strong weathering.
出处
《第四纪研究》
CAS
CSCD
北大核心
2004年第2期160-166,共7页
Quaternary Sciences
基金
国家自然科学基金项目 (批准号 :40 10 10 13 )资助
