张晓,
朱丽东^,,
黄颖,
李凤全,
熊文婷,
贾佳,
王天阳,
叶玮
浙江师范大学地理与环境科学学院, 浙江 金华 321004

基金项目: 国家自然基金科学项目（批准号：41572345和41971111）资助


详细信息

作者简介: 张晓, 女, 25岁, 硕士研究生, 自然地理学专业, E-mail:xiao_zjnu@163.com

通讯作者: 朱丽东, E-mail:zhulidong@zjnu.cn

中图分类号: P595;S151

收稿日期:2019-09-30
修回日期:2019-11-21
刊出日期:2020-01-30

The reticulated mechanism and its climatic implication of aggradation red earth

Zhang Xiao,
Zhu Lidong^,,
Huang Ying,
Li Fengquan,
Xiong Wenting,
Jia Jia,
Wang Tianyang,
Ye Wei
College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, Zhejiang



More Information

Corresponding author: Zhu Lidong,E-mail:zhulidong@zjnu.cn

MSC: P595;S151

--> Received Date: 30 September 2019
Revised Date: 21 November 2019
Publish Date: 30 January 2020


摘要
摘要:选取九江地区JL剖面网纹层段典型样品，针对红基质与白网纹的物质组成及理化性质展开异同分析，在此基础上探讨网纹红土形成环境。初步得到以下结论：1）红基质与白网纹的粒度组成、元素组成、风化特征基本一致，但铁元素有显著差异，"网纹"并非原生构造，不是岩性差异及差异风化的产物，而是同源物质经历化学风化过程中元素分馏的结果。2）地球化学分析、磁学分析和粘粒级矿物组成分析一致表明，白网纹与红基质在铁含量、铁氧化物形态、铁矿物类型方面存在明显差异。白网纹与红基质相比，全铁含量（4.30%）低于红基质（8.63%）；Fe³⁺/Fe²⁺比值（40.66）低于红基质（90.95）；游离铁量及游离度（7.01 g/kg，32.96%）低于红基质（76.21 g/kg，77.52%）；铁活化度和晶胶率（25.31%，37.77%）高于红基质（8.77%，9.69%）；赤铁矿和针铁矿含量极少，这充分表明白网纹局部存在明显的铁淋失。3）白网纹局部脱色机制主要受控于赤铁矿及其转化，红基质主导矿物为赤铁矿，并含有一定的磁赤铁矿和针铁矿，而白网纹则不含磁赤铁矿，赤铁矿含量也极少。此外高岭石含量也是影响色浅的因素之一，白网纹蛭石、高岭石含量（20.24%和45.08%）均略高于红基质（11.45%和41.82%）。4）赤铁矿的富集、局部铁迁移的特点，整体上指示高温、中强程度化学风化和季节性多水的环境。这在一定程度上暗示网纹红土形成时期气候高温多雨，且季节性反差增强。
关键词: 加积型红土/
网纹红土/
网纹化机制/
第四纪

Abstract:In South China, the land is mainly covered by red soil. In turn, the area is so called "red earth". The red clay develops from multi-type parent materials, including:granite, basalt, fluvial deposits, lake sediments, aeolian deposits, and so on. Among them, aeolian deposit, commonly called by aggradation red earth, is a good geological recorder due to which can record the quasi-continuous Pleistocene climate evolution history by soil sequences, similarly with the famous Chinese loess. The standard stratigraphy of aggradation red earth includes three typical soil units which are yellowish brown soil unit, homogeneous red soil unit, and reticular red soil unit. The reticular red soil unit is characterized by reticular structure, with red clay spotted by white clay. It is clearly to understand the climatic implication of reticular structure is very important for Quaternary climate reconstruct in the area. However, the question is still in debate. In this study, we collected a representative profile of aggradation red earth to systemically investigate the mechanism of reticular structure formation. The profile is labelled by JL (29°42'N, 116°02'E), and locating in the north slope of Lushan Mountains in Jiangxi Province, China. It is 18.46 m in thickness, including 4.46 m yellowish brown soil in the top and 14 m reticular red soil in the bottom. The physical and chemical characteristics had been compared between white clay and red clay, separating from the selected reticular red soil samples. Conclusions are as follow:(1) According to the analysis of grain size and element composition, the main difference between the red clay and the white clay lies in the enrichment of element Fe rather than their compositions or lithologic characters, result from element fractionization of homologous substance throughout the weathering process. (2) The content and valence state of element Fe existing in red clay obviously differ from those in white clay in accordance with geochemical analysis, magnetic analysis and clay mineral analysis. In contrast, the white clay is characterized by high leaching state, evidenced by lower Fe content, lower ratio of Fe³⁺/Fe²⁺, lower content of dissociative iron oxide, lower freeness, high activation grade Fe, and high ratio between Feo and Fed-Feo. (3) The partial decolourization of white clay is mainly controlled by the content of hematite. The predominant minerals of red clay are hematite, goethite and maghemite, however, white clay are not, except very little hematite. Besides, the content of kaolinite, to some extent, exerts an effect on decolourization of white clay in terms of higher vermiculite (20.24%) and kaolinite (45.08%) in white clay than those in red clay (11.45% and 41.82%). (4) The characteristics of enrichment of hematite and partial migration of Fe indicate high temperature, moderate chemical weathering and seasonal change of wetness, which goes to a further step and illustrate that it be high temperature and rainy, together with more distinct seasonal change.
Key words:aggradation red earth/
reticular red soil/
reticulated mechanism/
Quaternary



PDF全文下载地址:

http://www.dsjyj.com.cn/data/article/export-pdf?id=dsjyj_11731