日本地球惑星科学連合2018年大会

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[EJ] Eveningポスター発表

セッション記号 A (大気水圏科学) » A-CG 大気水圏科学複合領域・一般

[A-CG38] 北極域の科学

2018年5月24日(木) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:津滝 俊(東京大学)、漢那 直也(北海道大学 北極域研究センター)、鄭 峻介(北海道大学 北極域研究センター、共同)、中村 哲(北海道大学大学院地球環境科学研究院)

[ACG38-P22] 走査型電子顕微鏡を使ったグリーンランド氷床北西部SIGMA-Dアイスコア中の鉱物組成変動の解明

*永塚 尚子1東 久美子1,2本山 秀明1,2的場 澄人3藤田 耕史4山崎 哲秀5大沼 友貴彦6箕輪 昌紘3青木 輝夫7平林 幹啓1Dallmayr Remi8 (1.国立極地研究所、2.総合研究大学院大学 、3.北海道大学低温科学研究所、4.名古屋大学大学院環境学研究科、5.アバンナット、6.東京大学生産技術研究所 、7.岡山大学自然科学研究科、8.AWI)

キーワード:アイスコア、グリーンランド、走査型電子顕微鏡、鉱物組成

Snow and ice on glaciers and the ice sheet in the Arctic contain windblown mineral dust derived from local sediments as well as distant deserts. Dust deposited on the ice sheet in the past can be obtained by ice core drilling, and the variations in its sources and transportation processes can be reconstructed by particle analysis of ice cores. In this study, we analyzed morphology and surface chemistry of mineral dust particles in an ice core drilled in Northwest Greenland with Scanning Electron Microscope (SEM, QUANTA FEG 450) and Energy Dispersive X-ray Spectrometer (EDS).

The ice core was drilled at the SIGMA-D site (N77°64’, W59°12’) of 2100 m a.s.l. in 2014. The length is 222.72 m and the estimated age at 113 m depth is 350 years before present . The ice samples were collected every five years in plastic bottles and freeze dried on a polycarbonate filter to concentrate micro-particles. Then, the filter was coated with platinum (Pt) for SEM analysis.

The SEM observation revealed that the mean size of mineral dust in the SIGMA-D ice core ranged from 1-3μm, which is similar to that of the other Greenland ice core dust that seems to be derived from distant deserts. This suggests that the SIGMA-D ice core contained mainly long–range transported wind-blown mineral dust. The EDS alalysis also revealed the ice core contained mainly silicate minerals, especially clay minerals, that showed compositional variation among the samples. For example, Quartz and Feldspar contents were three times higher in 1935-1950 compared with the other periods. Furthermore, the variation trend also differed among the minerals. The trend of micas/illite, chlorite, and feldspar were similar to each other, but different from kaolinite. The two type of minerals were formed by different weathering processes. These results indicate that the ice core dust was likely derived from different sources in different period.