Systematic characterization of cosmic symplectites in the Acfer 094 carbonaceous chondrite

• 資料種別: 博士論文
• タイトル: Systematic characterization of cosmic symplectites in the Acfer 094 carbonaceous chondrite
• 著者・編者: 阿部, 憲一
• 著者標目: 阿部, 憲一
• 出版事項: Hokkaido University
• 出版年月日等: 2017-03-23
• 出版年（W3CDTF）: 2017-03-23
• 並列タイトル等: 炭素質コンドライトAcfer 094隕石における宇宙シンプレクタイトの系統的な特徴付け
• 寄与者: 圦本, 尚義; 永井, 隆哉; 橘, 省吾; 坂本, 直哉
• 授与機関名: 北海道大学
• 授与年月日: 2017-03-23
• 授与年月日（W3CDTF）: 2017-03-23
• 報告番号: 甲第12690号
• 学位: 博士(理学)
• 博論授与番号: 甲第12690号
• 本文の言語コード: eng
• NDC: 400
• 対象利用者: 一般
• 一般注記: We describe the petrographic occurrences, abundances, and compositional variations of symplectically intergrown Fe,Ni-sulfides and 17,18O-rich magnetite (Δ17O ~90‰), named cosmic symplectites (COS; Sakamoto et al., 2007), from the Acfer 094 (C3.0) ungrouped carbonaceous chondrite. A total of 314 COS studied in two polished sections of this meteorite are uniformly distributed in its matrix with ~600 ppm surface area abundance. No COS have been identified in the Acfer 094 dark inclusions (chondritic lithic clasts) which appear to have experienced extensive aqueous alteration prior to incorporation into the host meteorite. The structure of COS can be arranged in a hierarchy of four categories (from finer to coarser): (1) symplectite structure composed of nanocrystalline magnetite and Fe,Ni-sulfides, (2) submicron -sized wormy structure composed of nanocrystalline symplectites, (3) micrometer -sized irregular rope-like structure composed of wormy structure, and (4) aggregates of the rope-like structure. COS typically associate with fractured Fe,Ni-sulfides and lack Fe,Ni- metal. Most COS studied have smooth surfaces; four grains contain abundant pores. In a single COS, the pore- rich regions are depleted in sulfur and nickel relative to the pore-free regions, indicat ing that the former are depleted in Fe,Ni-sulfides. Most COS studied contain similar abundances of Fe,Ni-sulfides and magnetite, whereas Ni/(Fe+Ni) atomic ratio in Fe,Ni-sulfides ranges from 0 to 0.4. The lack of Fe,Ni-metal associated with COS supports the formation process proposed by Seto et al. (2008), i.e. oxidation of Fe,Ni-metal and sulfides by 17,18 O-rich water vapor in the outer part of the protoplanetary disk. The similar abundance ratio for Fe,Ni-sulfide and magnetite cannot be simply explained by oxidation processes of Fe,Ni-sulfide precursors after sulfurization of Fe,Ni-metal precursors for COS formation as proposed by Seto et al. (2008).; (主査) 教授 圦本 尚義, 教授 永井 隆哉, 准教授 橘 省吾, 助教 坂本 直哉; 理学院（自然史科学専攻）
• DOI: 10.14943/doctoral.k12690; https://doi.org/10.14943/doctoral.k12690
• 国立国会図書館永続的識別子: info:ndljp/pid/10370884; https://dl.ndl.go.jp/pid/10370884
• コレクション（共通）: 障害者向け資料
• コレクション（障害者向け資料：レベル1）: テキストデータ
• コレクション（個別）: 国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文; https://dl.ndl.go.jp/collections/A00014
• 収集根拠: 博士論文（自動収集）
• 受理日（W3CDTF）: 2017-07-03T04:10:06+09:00
• 作成日（W3CDTF）: 2017-03
• 記録形式（IMT）: PDF
• オンライン閲覧公開範囲: 国立国会図書館内限定公開
• デジタル化資料送信: 図書館・個人送信対象外
• 遠隔複写可否（NDL）: 可
• 掲載誌（URI）: http://dx.doi.org/10.14943/doctoral.k12690; http://hdl.handle.net/2115/65400
• 参照（URI）: http://hdl.handle.net/2115/65401
• 連携機関・データベース: 国立国会図書館 : 国立国会図書館デジタルコレクション; https://dl.ndl.go.jp

• 要約等: We describe the petrographic occurrences, abundances, and compositional variations of symplectically intergrown Fe,Ni-sulfides and 17,18O-rich ...