| 钱塘江中下游沉积物磁性特征及其对沉积动力环境的指示意义 |
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| 引用本文： | 张敏,时连强,郭俊丽,徐岱璐.钱塘江中下游沉积物磁性特征及其对沉积动力环境的指示意义[J].海洋地质与第四纪地质,2021(2):181-191. |
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| 作者姓名： | 张敏 时连强 郭俊丽 徐岱璐 |
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| 作者单位： | 自然资源部第二海洋研究所国家海岛开发与管理研究中心;华东师范大学河口海岸学国家重点实验室;南京大学地理与海洋科学学院 |
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| 基金项目： | 国家自然科学基金“河口湾潮滩沉积物来源的环境磁学诊断——以杭州湾庵东浅滩为例”(40806038)。 |
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| 摘 要： | 利用2010年1月与2010年8月采集的钱塘江中下游河床沉积物粒度和磁性测量数据以及2010年8月测量的流速数据,分析了沉积物粒度和磁性的时空分布特征,探讨了粒度和磁性参数对沉积动力环境的指示意义。结果表明:(1)冬季河床沉积物以粉砂和黏土为主,夏季以粉砂和砂为主,沉积物粒度呈现从中游到富春江水库逐渐变细、近口段到河口段逐渐变粗的规律,并且冬季粒度总体上细于夏季,指示夏季以及河口段较强的水动力环境。(2)磁性矿物含量从中游到下游呈现逐渐减少的趋势,夏季磁性矿物含量比冬季高。磁性矿物中亚铁磁性矿物占主导地位,夏季亚铁磁性矿物的含量高于冬季。(3)χfd%、χARM、χARM/SIRM和χARM/χ可以作为这个区域冬季<16μm的细颗粒沉积物的代用指标,χfd%和χARM/χ可以作为夏季<32μm细颗粒沉积物的代用指标。(4)沉积物磁性参数χfd%、χARM、χARM/χ和χARM/SIRM同样呈现出从中游到富春江水库逐渐变大、而从近口段到河口段逐渐变小的趋势,这与沉积物磁性矿物晶粒对沉积动力环境的响应是密切相关的,其中参数χfd%与χARM更能有效地反映沉积动力环境。
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| 关 键 词： | 环境磁学 源汇过程 沉积动力环境 钱塘江中下游 |
Magnetic properties of sediments and their implications for sedimentary dynamic environment in the middle and lower reaches of the Qiantang River |
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| ZHANG Min,SHI Lianqiang,GUO Junli,XU Dailu.Magnetic properties of sediments and their implications for sedimentary dynamic environment in the middle and lower reaches of the Qiantang River[J].Marine Geology & Quaternary Geology,2021(2):181-191. |
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| Authors: | ZHANG Min SHI Lianqiang GUO Junli XU Dailu |
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| Institution: | (State research center for island exploitation and management,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China;State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200241,China;School of Geography and Ocean Sciences,Nan Jing University,Nanjing 210023,China) |
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| Abstract: | Based on the particle size and magnetic characteristics of the sediments collected in the middle and lower reaches of the Qiantang River in January 2010 and August 2010,as well as the flow velocity data measured in August 2010,the temporal and spatial distribution of particle size and magnetism of the sediments are analyzed,and their indication significance to the sedimentary dynamic environment dicussed.Results show that the river bottom sediments are mainly composed of silt and clay in winter,but dominated by silt and sand in summer.The grain size of the sediments gradually gets fining from middle reaches to the Fuchunjiang Reservoir and becomes coarse from near-mouth section to estuary;the particle size is smaller in winter in general,indicating a stronger hydrodynamic environment in the estuary in summer.The content of magnetic minerals gradually decreases from the middle reaches to the lower reaches.The content of magnetic minerals in summer is higher than that in winter.Ferrimagnetic minerals dominate magnetic minerals,and there are more ferrimagnetic minerals in summer.χfd%,χARM,χARM/SIRM andχARM/χcan be used as proxies for the sediments finer than 16μm in the study area in winter,whileχfd%andχARM/χbe used as indicators for sediments finer than 32μm in summer.χfd%,χARM,χARM/χandχARM/SIRM also show an increasing trend from middle reaches to the Fuchunjiang Reservoir,while show a decreasing trend from near-mouth section to estuary.This is closely related to the response of the sediment magnetic crystals to the sedimentary dynamic environment.χfd%andχARMcan reflect the sedimentary dynamic environment more effectively. |
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| Keywords: | environmental magnetism source to sink sedimentary dynamic environment middle and lower reaches of the Qiantang River |
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