{"created":"2023-07-25T10:24:50.639290+00:00","id":4910,"links":{},"metadata":{"_buckets":{"deposit":"b602000d-8adc-4966-a5ae-6bd5b500b270"},"_deposit":{"created_by":19,"id":"4910","owners":[19],"pid":{"revision_id":0,"type":"depid","value":"4910"},"status":"published"},"_oai":{"id":"oai:air.repo.nii.ac.jp:00004910","sets":["1194:1195:1196:1220"]},"author_link":["14291"],"item_10006_alternative_title_32":{"attribute_name":"別タイトル","attribute_value_mlt":[{"subitem_alternative_title":"火山噴出物に記録された活火山直下の熱水系の進化過程　北海道十勝岳火山、木曽御嶽火山、福島吾妻　浄土平火山での事例研究"}]},"item_10006_biblio_info_34":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2020-03-24","bibliographicIssueDateType":"Issued"},"bibliographic_titles":[{}]}]},"item_10006_date_granted_41":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2020-03-24"}]},"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（理学）"}]},"item_10006_description_27":{"attribute_name":"内容記述（抄録）","attribute_value_mlt":[{"subitem_description":"This study aims to elucidate the evolutional process of the complex interaction between magma and hydrothermal system, focusing on the ash petrology of non-juvenile eruption products in geologic successions from multiple volcanoes. Petrological observation of individual ash grains was carried out for the following cases: (1) Holocene volcanic products from Tokachidake volcano (4.7ka, 3.3ka , and 1926AD) (Chapter 1); (2) volcanic ash from the 2014 hydrothermal eruption of Ontake volcano (Chapter 2); (3) Holocene volcanic tephra layers around 1331AD from Azuma-Jododaira volcano (Chapter 3). As a result, the conclusive remarks below were obtained.\n(1) Holocene volcanic products from Tokachidake volcano (4.7ka, 3.3ka, and 1926AD) (Chapter 1): Each sample of ash grains underwent alteration to various degrees from unaltered to intensely altered. Alteration was categorized into silica type (only silcia), alunite type (silica+alunite±kaolin group mineral), and kaolin type (silica+kaolin group mineral). All of the altered ash grains are derived from the acidic alteration zone in subvolcanic hydrothermal system of Tokachidake. The hydrothermal alteration was caused by the acid-sulfate-chloride hydrothermal fluid formed by volcanic vapor that separated from the intruded magma. The rock textures of the weakly altered ash grains were formed by acidic hydrothermal fluid-rock interaction at open-flow through-system. The reaction process is explained by that a large amount of acidic hydrothermal fluid passes through and reacts with the rocks. The brief, incomplete, acidic hydrothermal alteration was caused by the Tokachidake subvolcanic hydrothermal system temporally formed with a magma intrusion.\n(2) Volcanic ash from the 2014 hydrothermal eruption of Ontake volcano (Chapter 2): The petrographical and mineralogical study of ash grains from the 2014 Ontake volcano hydrothermal eruption resulted in the discovery of previously undescribed minerals in an active volcano. Aluminum-phosphate-sulfates (APS) minerals (woodhouseite), Zn-sulfide, and monazite were found in this ash grains. The discovery of woodhouseite in the volcanic ash of the Ontake 2014 hydrothermal eruption represents the first reported presence of these minerals within an active volcano. Furthermore, two types of woodhouseite were observed: zoned alunite-woodhouseite-APS and micro-wormy vein woodhouseite-APS. The genetic environment of APS minerals is proposed to be highly acidic hydrothermal fluids existing beneath the volcanic summit, formed by condensation with magmatic volatiles exsolved from the magma chamber underneath Ontake volcano. Under these conditions, an advanced argillic alteration assemblage formed, consisting of silica, pyrophyllite, alunite, and kaolinite/dickite, plus APS, among other minerals. Further detailed studies might prove that the presence of APS at Ontake is not an exception, but likely commonplace among such active volcanoes. These characteristics are an obvious similarity with the epithermal-porphyry environments.\n(3) Holocene volcanic tephra layers around 1331AD from Azuma-Jododaira volcano (Chapter 3): This study found eight tephra layers below, L1-1, L1-2, L2, L3, L4, L5, L6 and L7 from bottom to top. L1-1 and L1-2 were corelated with Az-OA unit (1331AD eruption), and L3 and L4 are corresponded layers from 1711AD eruption. For all samples from the eight layers, XRD and microscopic observation (binocular-stereoscopic microscope and SEM-EDS) had clarified the tendency of componentry change. L1-1, L1-2, L5, L7 are characterized by the X-ray peak of both 14Å-smectite and 7Å-kaolin or either of them, and by abundance of ash grains categorized into partly altered volcanic rock (PAVR), massive altered rock (MAR), and dense volcanic rock (DVR). While, L2, L3, L4, L6 are characterized by the X-ray peak of intense igneous minerals (plagioclase and pyroxene) with the disappearance (or decrease) of 14Å-smectite and 7Å-kaolin, and by abundance of unaltered ash grains as dense volcanic rock (DVR) and vesicular volcanic rock (VVR). Alterations in all samples are classified into acidic to neutral hydrothermal alterations, which are silica type (silica+titanium oxide±pyrite), pyrophyllite type (silica+pyrophyllite±alunite), kaolin type (silica+kaolin mineral±alunite), alunite type (silica+alunite), mica-chlorite type (silica+illite+sericite±chlorite±biotite), chlorite type (silica+chlorite±epidote) and mica-K-feldspar type (silica+chlorite+bioite+K-feldspar). Only L1-1 and L1-2 samples contain altered ash grains of all sets of the above alterations. Other samples than L1-1 and L1-2 indicated alterations of silica, alunite, kaolin, and pyrophyllite types with minor mica-chlorite type. Furthermore, some samples richly contain VVR-andesitic scoria or scoriaceous fragment (especially in L2), DVR-blocky highly crystalline andesitic lava and DVR-blocky holocrystalline andesitic rock (L4, L5, and L6). These ash grains (VVR-scoria) are possible to be an essential juvenile material. From these componentry trends, Jododaira volcano of Azuma volcano group seems to repeat the hydrothermal eruption derived from a well-developed subvolcanic hydrothermal system (L1-1, L3, L5, and L7) or the magmatic hydrothermal eruption with fragmentation of the hydrothermal alteration zone and an intruded magma (L1-2, L2, and L6).\nFrom these observations, this study defines three types of subvolcanic hydrothermal systems within active volcanoes: Tokachidake-type, Ontake-type, and Azuma-Jododaira-Type. Tokachidake type of subvolcanic hydrothermal system are directly driven by a magma intrusion, which accompanies the chemical and physical modification of the hydrothermal system. Ontake type is a well-developed and mature subvolcanic hydrothermal system similar to the epithermal-porphyry system. Finally, Azuma-Jododaira type is a subvolcanic hydrothermal system with repetitions of magmatic and non-juvenile eruptions. The above three types could be considered as the evolutional series of a subvolcanic hydrothermal system, corresponding to the very-early stage of the epithermal-porphyry system. Through initial (Tokachidake-type) and middle (Azuma-Jododaira type) stages, with various degrees of magma intrusion or eruption, the subvolcanic hydrothermal system evolves into the stable stage defined as Ontake-type during the ore-forming process in volcano.","subitem_description_type":"Other"}]},"item_10006_dissertation_number_42":{"attribute_name":"学位授与番号","attribute_value_mlt":[{"subitem_dissertationnumber":"甲第1324号"}]},"item_10006_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.20569/00005243","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":"井村, 匠"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2020-11-30"}],"displaytype":"detail","filename":"rihakuyoushikou1324.pdf","filesize":[{"value":"200.0 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/4910/files/rihakuyoushikou1324.pdf"},"version_id":"31953f93-db36-4a59-9485-ef3f4f2836e8"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2020-11-30"}],"displaytype":"detail","filename":"shihakukou1324.pdf","filesize":[{"value":"17.2 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"本文","url":"https://air.repo.nii.ac.jp/record/4910/files/shihakukou1324.pdf"},"version_id":"c9add58b-7060-4b9b-97ab-e5f5910e6ae2"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"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":"Evolutional process of subvolcanic hydrothermal system recorded in volcanic products　―Case studies on Tokachidake, Ontake, Azuma-Jododaira volcanoes in Japan―","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Evolutional process of subvolcanic hydrothermal system recorded in volcanic products　―Case studies on Tokachidake, Ontake, Azuma-Jododaira volcanoes in Japan―"}]},"item_type_id":"10006","owner":"19","path":["1220"],"pubdate":{"attribute_name":"公開日","attribute_value":"2020-11-30"},"publish_date":"2020-11-30","publish_status":"0","recid":"4910","relation_version_is_last":true,"title":["Evolutional process of subvolcanic hydrothermal system recorded in volcanic products　―Case studies on Tokachidake, Ontake, Azuma-Jododaira volcanoes in Japan―"],"weko_creator_id":"19","weko_shared_id":-1},"updated":"2023-07-25T10:59:46.096090+00:00"}