蔡倩^1,,
付伟^1,2,,,
伍健莹¹,
赵芹¹,
玉永珊¹,
邵亚¹,
罗鹏^1,3
1. 桂林理工大学地球科学学院, 广西 桂林 541004
2. 广西有色金属隐伏矿床勘查及材料开发协同创新中心, 桂林理工大学, 广西 桂林 541004
3. 广西壮族自治区自然资源厅, 广西 南宁 530028

基金项目: 国家自然科学基金重大研究计划培育项目(批准号: 91962107)和广西自然科学基金项目(批准号: 2019JJA150083和2020GXNSFGA297003)共同资助


详细信息

作者简介: 蔡倩, 女, 25岁, 硕士研究生, 土壤地球化学研究, E-mail: caiqian7788@163.com

通讯作者: 付伟, E-mail: fuwei@glut.edu.cn

中图分类号: P595;S153.6⁺1

收稿日期:2020-11-30
修回日期:2021-02-21
刊出日期:2021-09-30

Spatial distribution heterogeneity of rare earth element geochemistry in island soil under the joint constraints of volcanic rock and topography—A case study of Weizhou Island, Guangxi, China

CAI Qian^1,,
FU Wei^1,2,,,
WU Jianying¹,
ZHAO Qin¹,
YU Yongshan¹,
SHAO Ya¹,
LUO Peng^1,3
1. School of Earth Science, Guilin University of Technology, Guilin 541004, Guangxi
2. Collaborative Innovation Center for Exploration and Material Development of Guangxi Hidden Metal Deposits, Guilin University of Technology, Guilin 541004, Guangxi
3. Guangxi Zhuang Autonomous Region Department of Natural Resources, Nanning 530028, Guangxi


More Information

Corresponding author: FU Wei,E-mail:fuwei@glut.edu.cn

MSC: P595;S153.6⁺1

--> Received Date: 30 November 2020
Revised Date: 21 February 2021
Publish Date: 30 September 2021


摘要
摘要:海岛土壤地球化学特征的研究对于认识海岛表生地质环境有重要意义。本研究以我国最大的第四纪火山海岛——涠洲岛为案例，重点研究亚热带海岛环境下火山岩风化土壤的稀土元素（REE）地球化学特征，并探讨影响其空间分布的关键因素。结果表明，涠洲岛土壤REE总量（ΣREE）自然变化范围较大，介于59.07~575.30 mg/kg，平均值为285.53 mg/kg，高于中国大陆土壤背景值（163.86 mg/kg），指示火山岩风化海岛具有较高的土壤REE丰度。反距离权重插值法（IDW）分析指示，岛内土壤的REE含量高低变化呈现出以带状和斑块状为主体形态的空间分布不均一性，推断其成因与母质岩石类型和地形位置等因素密切相关。3种不同岩性的成土母岩的ΣREE含量变化序列为：玄武岩（236.66 mg/kg）>火山碎屑岩（215.58 mg/kg）>含生物碎屑海滩沉积物（18.99 mg/kg），对应的土壤ΣREE含量具有类似变化规律，即玄武岩土壤（307.20 mg/kg）>火山碎屑岩土壤（297.46 mg/kg）>含生物碎屑海滩沉积物土壤（89.73 mg/kg）。该证据指示母岩是控制岛内土壤REE含量变化的首位因素，玄武岩整体上易形成具有较高REE丰度的土壤，火山碎屑岩次之，而含生物碎屑海滩沉积物反之。此外，本研究还发现火山碎屑岩单一岩性区内，发育的土壤REE含量也会随地形地貌差异而出现显著变化，其原因是地形地貌制约了土壤矿物和化学风化程度，海蚀丘陵比海积平原更利于海岛土壤中REE次生富集作用的发生。
关键词: 海岛/
土壤地球化学/
稀土元素/
火山岩风化

Abstract:The study of soil geochemistry is of great significance for understanding the surface geological environment of islands. Weizhou Island(20°54'~21°10'N, 109°00'~109°15'E), located in Beibu Gulf of Guangxi Zhuang Autonomous Region, is the largest Quaternary volcanic island in China. It was taken as an example to study the geochemical characteristics of rare earth elements(REE) in weathered volcanic soils under subtropical island environment, and the key factors affecting REE spatial distribution are also investigated. The soil sampling range covers the entire 25.5 km² island with 500 m×500 m grid. A total of 87 surface soil samples(0~20 cm depth) were collected, and additionally 20 parent rocks samples including basalt, pyroclastic rocks and bioclastic beach sediments were obtained.
The results show that the island soil samples have a wide range of variability in REE content(59.07~575.30 mg/kg), with a mean contents at 285.53 mg/kg, which is relatively higher compared to Chinese mainland soils background value(163.86 mg/kg) and world soil background value(153.80 mg/kg). Inversely distance-weighted interpolation(IDW) analysis indicated that the soil REE content within the island presented a spatial heterogeneity with strip-like and patch-like patterns associated with parent rock lithology and topography. The parent rock is the primary factor controlling the spatial distribution pattern of soil REE content in the island. The variation sequence of REE contents in three different lithologies is as follows: basalt(236.66 mg/kg) >pyroclastic rock(215.58 mg/kg) >bioclastic beach sediments(18.99 mg/kg), and their corresponding soil appear similar REE variation rules, i.e., basalt weathered soil(307.20 mg/kg) >pyroclastic weathered soil(297.46 mg/kg) >bioclastic beach sediment weathered soil(89.73 mg/kg). Basalt is prone to form soils with high REE abundance, followed by pyroclastic rocks, and bioclastic beach sediments are the opposite. In addition, significant REE contents variations were found even within the same volcano-stratigraphic unit. There is a positive correlation between soil REE contents and altitude. The possiable reason is that topography affected the degree of chemical weathering. The marine erosion hilly area with high altitude has suffered stronger chemical weathering than the marine plain area the low altitude, which is more conducive to the occurrence of REE secondary enrichment in the island soil.
Key words:Weizhou Island/
soil geochemistry/
rare earth elements/
weathering of volcanic rocks



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