{"created":"2023-07-25T10:25:11.483383+00:00","id":5394,"links":{},"metadata":{"_buckets":{"deposit":"e36bb173-0eb7-4f95-9548-671b5ec3499e"},"_deposit":{"created_by":15,"id":"5394","owners":[15],"pid":{"revision_id":0,"type":"depid","value":"5394"},"status":"published"},"_oai":{"id":"oai:air.repo.nii.ac.jp:00005394","sets":["1194:1195:1196:1385"]},"author_link":["15008"],"item_10006_alternative_title_32":{"attribute_name":"別タイトル","attribute_value_mlt":[{"subitem_alternative_title":"ボツワナ北東部、Matsitama片岩帯、Mowana銅鉱床の多段階Cu鉱化作用"}]},"item_10006_biblio_info_34":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2021-03-22","bibliographicIssueDateType":"Issued"},"bibliographic_titles":[{}]}]},"item_10006_date_granted_41":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2021-03-22"}]},"item_10006_degree_grantor_40":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"秋田大学"}],"subitem_degreegrantor_identifier":[{"subitem_degreegrantor_identifier_name":"11401","subitem_degreegrantor_identifier_scheme":"kakenhi"}]}]},"item_10006_degree_name_39":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（資源学）"}]},"item_10006_description_27":{"attribute_name":"内容記述（抄録）","attribute_value_mlt":[{"subitem_description":"The Mowana hydrothermal Cu deposit is located within the Matsitama-Motloutse 　Complex in the southwestern part of the Zimbabwe Craton in the northeastern part of 　Botswana. The deposit is in the northern-most flank of the Matsitama Schist Belt, 　which makes one of the four granite-greenstone belts of north-eastern Botswana. It is 　poorly understood and has received less documentation since its discovery, by 　comparison to other ore deposits in the same area. Mowana deposit is unique from 　other Archean greenstone belt vein deposits in the sense that instead of Au 　mineralization it is rather dominated by Cu mineralization. There is a large, inferred　time gap between rock formation and mineralization. The deposit is hosted by the 　NNE-striking and nearly vertically dipping (70-80°) Bushman Lineament (shear zone)　within the graphitic schist lenses in the carbonaceous and argillaceous 　metasedimentary rocks of the Neoarchean to Paleoproterozoic Matsitama 　Sedimentary Group. Within the Matsitama Sedimentary Group, the Mowana deposit 　is hosted by rocks belonging to the Bushman Mine group, a sedimentary fining upward 　sequence. The Matsitama Sedimentary Group is enclosed within the foliated 　granitoids of the Matsitama-Motloutse Complex. The ca. 0.2 Ga Phanerozoic Karoo 　Supergroup overlies these units. 　The host metasedimentary rocks: limestone, argillite and graphitic schist, as well 　as the surrounding granites, suffered from hydrothermal alteration. The hydrothermal 　alteration is characterized by silicification, chloritization, epidotization, sericitization, 　hematite, and carbonate alterations. Based on the alteration mineral assemblage, the 　main mineralization stage is attributed to near-neutral pH fluids at temperatures 　between ~200 °C and ~>340 °C. The temperatures obtained from the chlorite II　geothermometry of the Type 1 veins coincides with the above temperature in the range 　340-400 °C and a modal temperature of 370-380 °C.　The base metal mineralization of the Mowana deposit evolved in at least two 　hydrothermal vein types. The first mineralization type, represented by the 　quartz+calcite±K-feldspar veins and breccias, is characterized by the precipitation of 　principal chalcopyrite with pyrite, minor bornite and trace amounts of galena. The Type　2, represented by quartz+calcite±fluorite veins, hosts appreciable amounts of galena. 　The supergene mineralization is widely distributed in the shallow levels (up to 70 m 　below the surface) of the deposit. Supergene enrichment is manifested by the 　significant presence of chalcocite, bornite, covellite and anglesite. Oxidation is 　characterized by Fe-oxides and Cu carbonates: malachite, goethite, and hematite. The 　ore mineral assemblage of pyrite+chalcopyrite+bornite paired with the temperature 　obtained from the chlorite geothermometry from the Type 1 veins was used to 　determine the sulfidation state of the Mowana deposit. The ore mineral assemblage 　of the Type 1 veins lies on the pyrite+chalcopyrite+bornite buffer line at a temperature 　of 340 to 400 °C indicating that the Type 1 veins evolved under a transition between 　intermediate and high sulfidation state.　Chalcopyrite is the principal Cu-bearing mineral, which also contains an average 　67.4 ppm of Ag which may be due to incorporation of Ag in the Cu site. Galena from 　the Type 2 veins has high contents of Se with an average of 1231 ppm, possibly 　incorporated as PbSe. The average Ag content in galena from the Type 2 veins is 58.9 　ppm. The average Co, Ni, and As contents in pyrite are 143 ppm, 33.6 ppm, and 107 　ppm, respectively.III　Fluid Inclusion analysis was also conducted. Two-phase (liquid and gas) fluid 　inclusions were observed in the mineralized quartz veins. However, the fluid inclusions 　were too small to perform microthermometry. 　The carbon isotopic composition of graphite from graphitic schist are from -21.0 　to -29.8 ‰ (average 26 ‰) indicating a biogenic origin, possibly from cyanobacteria 　living in shallow water. The 　13C values of the metacarbonates range from 6.05 to 6.89 　‰ which is higher than the global trend at the time of deposition and rarely observed 　in Archean carbonates. These heavier values may be explained by diagenetic 　carbonate precipitation during which dissolved inorganic C is enriched in 13C by 　methanogenic processes, or alternatively by burial of reduced carbon in an isolated 　basin at that time, with the residual dissolved carbon being enriched in 13C. The carbon 　isotopic compositions of the calcite of Type 1 veins ranging from 0.46 to 0.53 ‰ could　indicate derivation from a mixed source including C from both host rock types. The 　　18O of the quartz is in the range 9.25 to 10.30 ‰ relative to Standard Mean Water 　Ocean Water (SMOW). The 　18O values of calcite range from -12.42 to -22.34 ‰ with 　respect to Vienna Pee Dee Belemnite (VPDB). The calculated temperature from the 　co-existing mineral pairs of quartz and calcite in equilibrium range between 250 to 360 　°C.　Sulfur isotopic ratios determined on the sulfides from Type 1, Type 2 and 　diagenetic pyrite help to understand the evolution of the hydrothermal system. The 　sulfides, chalcopyrite, chalcocite and galena from Type 1 and Type 2 veins, recorded 　isotopic compositions 　34S in the range -5 ‰ to +4 ‰. These values may indicate a 　magmatic sulfur source of S and/or leaching of the host metasedimentary rocks. 　However, 　34S of diagenetic pyrite disseminated in silicified limestone and pyrite from IV　a quartz+calcite±K-feldspar vein recorded sulfur isotopic values of +15.4 ‰ and +18.0　‰. The values can be explained by closed system reduction of seawater sulfate,　followed by remobilization of the 　34S rich diagenetic pyrite during brecciation as the 　possible sources of S. ","subitem_description_type":"Other"}]},"item_10006_dissertation_number_42":{"attribute_name":"学位授与番号","attribute_value_mlt":[{"subitem_dissertationnumber":"甲第1368号"}]},"item_10006_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.20569/00005716","subitem_identifier_reg_type":"JaLC"}]},"item_10006_publisher_28":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"秋田大学"}]},"item_10006_version_type_35":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_970fb48d4fbd8a85","subitem_version_type":"VoR"}]},"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":"KOOGANNE, AMOGELANG"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2021-06-03"}],"displaytype":"detail","filename":"shihakuyoushikou1368.pdf","filesize":[{"value":"168.6 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"内容要旨及び審査結果要旨","url":"https://air.repo.nii.ac.jp/record/5394/files/shihakuyoushikou1368.pdf"},"version_id":"e9014d71-7f7c-4e69-bc71-843fd1c60b1a"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2022-03-30"}],"displaytype":"detail","filename":"shihakukou1368.pdf","filesize":[{"value":"5.5 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"本文","url":"https://air.repo.nii.ac.jp/record/5394/files/shihakukou1368.pdf"},"version_id":"6553b2fa-b6e6-45e8-af1e-6933999013a4"}]},"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":"doctoral thesis","resourceuri":"http://purl.org/coar/resource_type/c_db06"}]},"item_title":"Multi-stage Cu Mineralization of the Mowana Copper Deposit, Matsitama Schist Belt, NE Botswana","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Multi-stage Cu Mineralization of the Mowana Copper Deposit, Matsitama Schist Belt, NE Botswana"}]},"item_type_id":"10006","owner":"15","path":["1385"],"pubdate":{"attribute_name":"公開日","attribute_value":"2021-06-03"},"publish_date":"2021-06-03","publish_status":"0","recid":"5394","relation_version_is_last":true,"title":["Multi-stage Cu Mineralization of the Mowana Copper Deposit, Matsitama Schist Belt, NE Botswana"],"weko_creator_id":"15","weko_shared_id":-1},"updated":"2023-07-25T10:44:18.065854+00:00"}