| 摘要: |
| 为寻找有效判别潮滩沉积微相的磁学指标，以便将环境磁学更好地应用于河口古环境演变及海平面重建，本研究在九龙江口浒茂洲东部潮滩4个亚带：高潮滩、中潮滩、低潮滩和潮下带，采集23个次表层沉积物样品，进行粒度和磁性测量。结果显示，磁性参数χ、SIRM由陆向海增大且在低潮滩和潮下带呈现显著高值，反映潮滩亚铁磁性矿物的绝对含量由陆向海增加；参数组合χARM、χARM/χ、χARM/SIRM在高、中潮滩呈现高值，低潮滩和潮下带呈现低值，反映细颗粒SP/SD亚铁磁性矿物富集于高、中潮滩，而粗颗粒PSD/MD铁磁性矿物富集于低潮滩和潮下带，揭示九龙江河口潮滩沉积动力对磁性矿物的分选作用。磁性参数组合χARM/χ、χARM/SIRM可作为九龙江口高潮滩和中潮滩的有效识别指标。 |
| 关键词: 沉积动力 磁性矿物 沉积微相识别 九龙江河口潮滩 |
| DOI：10.11759/hykx20210319004 |
| 分类号:P512.2 |
| 基金项目:福建省中青年教师教育项目（JAT190366）；闽南师范大学博士启动项目（L21710）；福建省大学生创新创业训练计划项目（202010402050） |
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| Mineral magnetic characteristics of tidal flat surficial sediments and their implications for sedimentary environment identification in the Jiulong Estuary |
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PAN Da-dong, LIAO Zi-hui, LIANG Wen-qing, LIU Ya-fei, XIAO Yi-qi, ZHU Chun-jin
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School of History and Geography, Minnan Normal University, Zhangzhou 363000, China
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| Abstract: |
| This study seeks effective magnetic proxies to recognize sedimentary microfacies in the tidal flat in the Jiulong Estuary to confirm if environmental magnetism is better applied to paleo-environmental and sea-level reconstruction. In this study, 23 subsurficial sediment samples were obtained from the tidal flat in the Jiulong Estuary in four sedimentary environments:upper tidal flat, middle tidal flat, lower tidal flat, and subtidal zone, and their grain size and magnetic properties were measured. Results showed that χ and SIRM increase from the upper tidal flat to the subtidal zone and present considerably high values in the lower tidal flat and subtidal zone, indicating the increase of the absolute content of the magnetic mineral from land to sea. The magnetic parameter assemblage of χARM, χARM/χ, and χARM/SIRM exhibit high values in the upper to middle tidal flat, whereas low values are obtained in the lower tidal flat and subtidal zone, reflecting that the SP/SD of fine ferromagnetic minerals are enriched in the upper to middle tidal flat, while the PSD/MD of coarse-grained ferromagnetic minerals are enriched in the lower tidal flat and subtidal zone. This reveals that at the Jiulongjiang river mouth, the distribution of magnetic minerals was controlled by the hydrodynamic sorting in the tidal flat. This work proposed that magnetic properties χARM/χ and χARM/SIRM are effective indicators to identify the upper tidal flat and middle tidal flat in the late quaternary stratigraphy in the Jiulong mouth. |
| Key words: sedimentary dynamics magnetic mineral identification of sedimentary microfacies tidal flat, Jiulong Estuary |
