{"created":"2021-03-01T06:34:10.697874+00:00","id":26267,"links":{},"metadata":{"_buckets":{"deposit":"733e0b36-d02a-4521-b7d8-aa45aab35ca3"},"_deposit":{"id":"26267","owners":[],"pid":{"revision_id":0,"type":"depid","value":"26267"},"status":"published"},"_oai":{"id":"oai:nagoya.repo.nii.ac.jp:00026267","sets":["879:1183:2103:2104"]},"author_link":["78860","78861","78862","78863"],"item_1615768549627":{"attribute_name":"出版タイプ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_970fb48d4fbd8a85","subitem_version_type":"VoR"}]},"item_9_alternative_title_19":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"CHIME dating of monazite in graphitic schist, Isua Supracrustal Belt, Greenland","subitem_alternative_title_language":"en"}]},"item_9_biblio_info_6":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2017-03-31","bibliographicIssueDateType":"Issued"},"bibliographicPageEnd":"65","bibliographicPageStart":"63","bibliographicVolumeNumber":"1","bibliographic_titles":[{"bibliographic_title":"名古屋大学年代測定研究","bibliographic_titleLang":"ja"}]}]},"item_9_description_4":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Biogenic graphite in > 3.7 Ga metasediments, Isua Supracrustal Belt (ISB), West Greenland, has been reported as the oldest remnant of life. Little is yet understood, however, about the ecosystem distributed throughout the >3.7 Ga ocean. Our group performed a geological survey of the west side of the ISB and investigated the petrographic and geochemical characteristics of metasediments to reconstruct the depositional environment. The chemical Th-U-total Pb isochron method (CHIME) was conducted on monazite associated with biogenic graphite to determine the age. Samples collected in the studied area were roughly divided into the magnetite-rich type, distributed in the northeast to south, and the silicate-rich type, distributed mostly in the northwest, based on the dominant minerals. Bulk, amphibole, and chlorite chemical compositions of the samples showed that the silicate-rich type is rich in Mg, whereas the magnetite-rich type is abundant in Fe, suggesting that the Mg-rich characteristics of the metasediments in the northwest are a primary signature. The Ti and Al concentrations of the banded iron formations (BIFs) and graphite-rich metasediments were positively correlated, indicating that detrital components contributed to both. The monazite in the graphite-rich sample had a CHIME age of 3630±91Ma, within the age range determined for prograde metamorphism and detrital zircon in a previous report. The occurrence of monazite suggests that the monazite was syngenetic with the host rocks and probably derived from detritus, and that its age was either modified during metamorphism or crystalized during diagenesis to early metamorphism. Our results indicate that the metasediments in the northwest of the area studied probably deposited where clastic components such as Mg, Ti and Al were supplemented at a relatively high rate. If this is so, photosynthetic microorganisms might have flourished in the shallow ocean of >3.7Ga.","subitem_description_language":"en","subitem_description_type":"Abstract"},{"subitem_description":"西グリーンランド・イスア表成岩帯 (約38億年前)では生物由来グラファイトが発見されている。しかしながら、グラファイトの前駆物質である微生物の棲息環境や微生物種について詳細は明らかになっていない。本研究では生物由来グラファイトの報告があったイスア表成岩帯の西部において、黒色片岩及び縞状鉄鉱層 (Banded iron formation: BIF)の地質学的・地球化学的特徴及び希土類元素含有鉱物の産状とChemical Th-U-total Pb Isochron Method(CHIME)年代測定から堆積環境を復元することにより、当時の微生物の棲息環境に制約を与えることを目的とした。イスア表成岩帯西部ではBIFの層が複数南北に渡り分布しており、黒色片岩層は西部北端に位置するBIFの層間に分布している。露頭では黒色片岩及びその周辺のBIFはシリケイトに富むのに対して、南側のBIFはマグネタイトに富む様子が観察された。誘導結合プラズマ質量分析計による全岩化学組成分析結果では、黒色片岩及びその周辺のBIFのFe2O3/MgO比は低くMgに富む傾向を示すのに対して、南側のBIFはFe2O3/MgO比が高くFeに富むことがわかった。緑泥石及び角閃石の化学組成においても同様に、北側はMgに富み、南側はFeに富む傾向がみられた。黒色片岩及びBIF試料中のAl2O3及びTiO2量(wt%)は正相関を示しており、黒色片岩及びその周辺のBIFがAl、Tiに富むのに対して、南側のBIFはAl、Tiに乏しい傾向が見られた。また、グラファイトに富む黒色片岩試料中の希土類鉱物を走査型電子顕微鏡で観察したところ、モナザイトがグラファイトに富む層のみに葉理に調和的な産状で卓越していることがわかった。モナザイトのCHIME年代測定結果は3630±91Maであり、過去の研究で報告された砕屑性ジルコンの年代とプログレード変成作用の年代を範囲に含むことがわかった。モナザイトの産状から考えると、モナザイトはもともと砕屑物として混入した後、変成中に年代のリセットを受けた可能性、初期続成作用から変成作用の間に岩石中で結晶化した可能性の両方が考えられる。以上の結果は、黒色片岩及びその周辺のBIFがMg、Al、Ti、希土類元素を含む地殻砕屑物が多く混入するような浅海域で堆積したことを示しており、当時繁茂していた微生物は浅海で繁茂していた光合成細菌であった可能性を示唆するものと考えられる。","subitem_description_language":"ja","subitem_description_type":"Abstract"}]},"item_9_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.18999/nagubc.1.63","subitem_identifier_reg_type":"JaLC"}]},"item_9_publisher_32":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"名古屋大学宇宙地球環境研究所年代測定研究部","subitem_publisher_language":"ja"}]},"item_9_select_15":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_select_item":"publisher"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"open access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_abf2"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"大友, 陽子","creatorNameLang":"ja"}],"nameIdentifiers":[{"nameIdentifier":"78860","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"加藤, 丈典","creatorNameLang":"ja"}],"nameIdentifiers":[{"nameIdentifier":"78861","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Ohtomo, Yoko","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"78862","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Kato, Takenori","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"78863","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2018-08-17"}],"displaytype":"detail","filename":"063-065_2016.pdf","filesize":[{"value":"1.3 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"063-065_2016.pdf","objectType":"fulltext","url":"https://nagoya.repo.nii.ac.jp/record/26267/files/063-065_2016.pdf"},"version_id":"0b561c5c-e1b5-4494-847c-05e8619adc2a"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"Isua Supracrustal Belt","subitem_subject_scheme":"Other"},{"subitem_subject":"biogenic graphite","subitem_subject_scheme":"Other"},{"subitem_subject":"rare earth elements","subitem_subject_scheme":"Other"},{"subitem_subject":"monazite","subitem_subject_scheme":"Other"},{"subitem_subject":"CHIME","subitem_subject_scheme":"Other"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"グリーンランド・イスア表成岩帯の石墨片岩中に含まれるモナザイトのCHIME年代測定","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"グリーンランド・イスア表成岩帯の石墨片岩中に含まれるモナザイトのCHIME年代測定","subitem_title_language":"ja"}]},"item_type_id":"9","owner":"1","path":["2104"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2018-08-17"},"publish_date":"2018-08-17","publish_status":"0","recid":"26267","relation_version_is_last":true,"title":["グリーンランド・イスア表成岩帯の石墨片岩中に含まれるモナザイトのCHIME年代測定"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-01-16T04:13:19.143108+00:00"}