| 白令海和西北冰洋表层沉积物磁化率特征初步研究 |
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| 引用本文： | 汪卫国,戴霜,陈莉莉,吴日升,余兴光.白令海和西北冰洋表层沉积物磁化率特征初步研究[J].海洋学报,2014,36(9):121-131. |
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| 作者姓名： | 汪卫国 戴霜 陈莉莉 吴日升 余兴光 |
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| 作者单位： | 1.国家海洋局 第三海洋研究所,福建 厦门 361005 |
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| 基金项目： | 中国第四次北极科考项目(CHINARE-2010);海洋行业公益性项目(201105022-2,201205003);南北极环境综合考察与评估专项(CHINARE2012-03-02,CHINARE2013-04-03-03)。 |
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| 摘 要： | 为了准确解释环境磁学参数记录的极地古气候环境变化信息,本研究对白令海和西北冰洋61个站位的表层沉积物进行了高、低频质量磁化率(χ)、非磁滞磁化率(χARM)和磁化率-温度(k-T)分析,以探明该区沉积物中磁性矿物的种类、来源与搬运路径。结果显示,样品的χ具有明显的地域分布特征。白令海的χ值整体高于楚科奇海,并在育空河口外侧和圣劳伦斯岛南侧较高,向北和向西南方向逐渐减小。楚科奇海中东部陆架上表层沉积χ值高于阿拉斯加沿岸,而西北冰洋深海平原和洋脊区的χ值最低。χARM的变化趋势与质量磁化率相似,但频率磁化率的变化趋势与质量磁化率正好相反。k-T分析结果显示阿留申海盆沉积物中的铁磁性矿物以磁赤铁矿占主导,白令海陆架育空河口外侧和圣劳伦斯岛南北两侧为磁铁矿,白令海陆架西部和楚科奇海陆架中东部为磁赤铁矿和磁铁矿,楚科奇海阿拉斯加沿岸为黄铁矿,而西北冰洋陆坡、深海平原和洋脊区为胶黄铁矿和黄铁矿,但高纬度区沉积物中的胶黄铁矿含量更高。沉积物中磁性矿物的区域性分布受沉积物来源、洋流和底质环境等因素的控制。白令海和楚科奇海陆架磁赤铁矿来源于亚洲大陆,白令海陆架东部的磁铁矿来自育空河流域,阿拉斯加沿岸沉积物中的黄铁矿,应为阿拉斯加西北部陆源侵蚀来源的或早期成岩作用形成的,西北冰洋深海盆区的胶黄铁矿,为自生成因的。
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| 关 键 词： | 白令海 西北冰洋 磁化率 磁性矿物 沉积物来源 |
| 收稿时间： | 2013/11/11 0:00:00 |
| 修稿时间： | 2013/12/26 0:00:00 |
Magnetic susceptibility characteristics of surface sediments in Bering Sea and western Arctic Ocean: preliminary results |
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| Wang Weiguo,Dai Shuang,Chen Lili,Wu Risheng and Yu Xingguang.Magnetic susceptibility characteristics of surface sediments in Bering Sea and western Arctic Ocean: preliminary results[J].Acta Oceanologica Sinica (in Chinese),2014,36(9):121-131. |
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| Authors: | Wang Weiguo Dai Shuang Chen Lili Wu Risheng and Yu Xingguang |
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| Institution: | 1.Third Institute of Oceanography, State Oceanic Adiministration, Xiamen 361005, China2.Key Laboratory of Western China’s Environmental Systems Ministry of Education, Research School of Arid Environment and Climate Change, Lanzhou University, Lan Zhou 730000, China |
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| Abstract: | The mass-dependent magnetic susceptibility (χ) with low and high frequency, anhysteretic susceptibility (χARM) and temperature-dependent susceptibility (k-T) of 61 surface sediment samples obtained from Bering Sea and western Arctic Ocean were measured with an attempt to find the composition, province and transport of magnetic minerals, which is helpful to accurately decipher the paleo-climate and environmental information recorded by the magnetic parameters in Arctic area. The results show that the χ values of surface sediments have an evident regional difference. The χ values are commonly higher in Bering Sea than that in Chukchi Sea, and they are the lowest in the plains and ridges of high western Arctic Ocean. The χ values are the highest off the Yukon River estuary and to the south of St. Lawrence Island in Bering Sea shelf, decreasing northward and south-westward. The χ values are relatively higher in the central-eastern Chukchi Sea shelf than that off the Alaskan coast. The χARM share the common variation trends of χ, however, the frequency-dependent susceptibility changes oppositely to that of χ. The analysis of k-T shows that the magnetic mineral in surface sediments in Aleutian Basin is maghemite, and off the Yukon River estuary and to the south of St. Lawrence Island is magnetite, and both maghemite and magnetite occur in the western shelf of Bering Sea and central-eastern shelf of Chukchi Sea. The magnetic mineral of surface sediment off the Alaskan coast is pyrite, while in the slope, plains and ridges of high western Arctic Ocean, the magnetic minerals are greigite and pyrite, but the content of greigite is higher in high latitude. The regional distribution of magnetic minerals in surface sediments is controlled by the sources of sediments, currents and bottom environments. The maghemite in the shelf of Bering Sea and Chukchi Sea is from the Asian main land, and the magnetite in eastern Bering Sea shelf is from the watershed of Yukon River. Pyrite off the Alaskan coast may be terrigenous or formed during the early diagenesis, while the greigite in high western Arctic Ocean is biogenous. |
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| Keywords: | Bering Sea western Arctic Ocean magnetic susceptibility magnetic minerals sediment sources |
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