龚亚玲^1,2,,
胡忠行^1,,,
李文³,
周云鹏¹,
朱丽东¹
1. 浙江师范大学地理与环境科学学院, 浙江 金华 321004
2. 重庆市荣昌中学校, 重庆 402460
3. 东华理工大学地球科学学院, 江西 南昌 330013

基金项目: 国家自然科学基金项目（批准号：41572345）资助


详细信息

作者简介: 龚亚玲, 女, 27岁, 硕士研究生, 自然地理学专业, E-mail:gongyaling0201@qq.com

通讯作者: 胡忠行, E-mail:znuhzx@zjnu.cn

中图分类号: P318;P534.63

收稿日期:2019-12-28
修回日期:2020-05-22
刊出日期:2021-01-30

Magnetic properties of weathering laterite derived from basalt, Zhejiang, and its responses to soil-forming processes

GONG Yaling^1,2,,
HU Zhongxing^1,,,
LI Wen³,
ZHOU Yunpeng¹,
ZHU Lidong¹
1. College of Geography and Environmental Science, Zhejiang Normal University, Jinhua 321004, Zhejiang
2. Chongqing Rongchang Middle School, Chongqing 402460
3. College of Geosciences, East China Institute of Technology, Nanchang 330013, Jiangxi


More Information

Corresponding author: HU Zhongxing,E-mail:znuhzx@zjnu.cn

MSC: P318;P534.63

--> Received Date: 28 December 2019
Revised Date: 22 May 2020
Publish Date: 30 January 2021


摘要
摘要:以位于浙江磐安县的玄武岩风化壳红土（XZ剖面）为研究对象，对其进行系统环境磁学分析，结合常量元素、漫反射光谱、有机质等分析手段，研究玄武岩风化壳红土的磁性特征，并探讨磁性特征与风化成土过程之间的关系。结果表明：在风化成土初期，玄武岩风化壳红土磁性较强，具有较高的磁化率（χ）和饱和等温剩磁（SIRM），磁性矿物主要为原生多畴（MD）颗粒亚铁磁性矿物（磁铁矿、钛磁铁矿），磁性特征继承了母岩特性；随着风化成土作用的增强，土壤中的原生亚铁磁性矿物逐渐转化为次生不完全反铁磁性矿物（赤铁矿、针铁矿等），导致土壤磁性降低，但细颗粒磁性矿物逐渐增加；强风化成土阶段，原生亚铁磁性矿物进一步减少，反铁磁性矿物仍表现出一定高值，同时大量成土成因的细颗粒次生强磁性矿物（SP颗粒磁铁矿、磁赤铁矿）逐渐生成，导致土壤χ持续升高。本研究显示玄武岩风化壳红土的磁学特征与风化成土过程具有紧密的关系，磁性参数χ_fd%可作为亚热带地区玄武岩风化壳红土成土过程和成土强度的指示指标。
关键词: 玄武岩/
风化壳红土/
磁性特征/
成土过程

Abstract:Magnetic properties of red earth have been widely applied to establish paleo-climatic change. However, the influence factors of magnetic properties of red earth which developed on basalt have not been fully understood, which complicates the environmental interpretation. The profile of Xinzhai (XZ:29°13'07″N, 120°44'15″E; 516 m) located in the Dapan mountain area in central Zhejiang Province, the outlying strata are mainly volcanic rocks, most of which are extrusive rocks, belonging to the Xinchang Cenozoic basalt series in Shengxian, Zhejiang. It has a subtropical monsoon climate. The depth of XZ profile is 390 cm in thickness. Samples were collected at 5 cm intervals. A total of 78 samples are obtained. According to the particle size of residual parent rock and the content of plant roots, the profile can be divided into three layers: first layer, 390~270 cm; second layer, 270~90 cm; third layer, 90~0 cm. In this paper, we present the results of environmental magnetic, geochemical, granulometric, diffuse reflectance spectroscopy and organic matter analyses of sediments of XZ profile. The aim of the study was to assess the influence factor of magnetic properties and its environmental significance, as well as the relation between magnetic properties and weathering and pedogenesis processes.
The results reveal that during the early stage of weathering and pedogenesis processes, sedimentary magnetic properties are dominated by multidomain (MD) ferrimagnetic minerals (i.e. magnetite, titanomagnetite) and characterized by higher χ and SIRM. In this stage, the magnetic properties of red earth mainly inherit the characteristic of parent rock. Then with the weathering and pedogenesis intensity increasing, the ferromagnetic mineral transformed into the sub-antiferromagnetic mineral (i.e. hematite, goethite), the χ and SIRM show an overall upwards-decreasing trend. However, the χ_fd% and χ_ARM/SIRM show an overall upwards-increasing trend, demonstrated that the concentration of proportion of finer-grained magnetic minerals are increased. In the stage of intense weathering and pedogenesis, the main characteristic of magnetic properties characterized by the abundant postnatal magnetic minerals (SP particle) formed and lead to the highest χ_fd%, χ_ARM/SIRM, χ, while the original magnetic minerals were decreased. It demonstrates that the weathering and pedogenesis has a significant effect on magnetic properties, exhibited by with the weathering and pedogenesis intensity of red earth which developed on basalt increasing, the pedogenesis postnatal finer-grained magnetic minerals increasing. This study revealed that the magnetic particle related parameters (e.g. χ_fd%) can be regarded as an indicator of the weathering and pedogenesis intensity in subtropical regions.
Key words:basalt/
weathering crust/
magnetic property/
soil-forming process



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