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Geology, mineralogy, and sulfur isotopic studies of proximal volcanic products at the Tangkuban Parahu Volcano, Indonesia.
https://doi.org/10.20569/00004199
https://doi.org/10.20569/000041998e604fd2-a429-4e12-816c-f5aedcfd75e0
| 名前 / ファイル | ライセンス | アクション |
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内容要旨及び審査結果要旨 (247.6 kB)
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本文 (2.0 MB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||||
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| 公開日 | 2019-11-18 | |||||||
| タイトル | ||||||||
| タイトル | Geology, mineralogy, and sulfur isotopic studies of proximal volcanic products at the Tangkuban Parahu Volcano, Indonesia. | |||||||
| 言語 | ||||||||
| 言語 | eng | |||||||
| 資源タイプ | ||||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_db06 | |||||||
| 資源タイプ | doctoral thesis | |||||||
| ID登録 | ||||||||
| ID登録 | 10.20569/00004199 | |||||||
| ID登録タイプ | JaLC | |||||||
| アクセス権 | ||||||||
| アクセス権 | open access | |||||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||||
| 別タイトル | ||||||||
| その他のタイトル | インドネシア，タンクバンパラフ火山噴出物近傍相の地質学、鉱物学、および硫黄同位体化学的研究 | |||||||
| 作成者 |
SYAHREZA, SAIDINA ANGKASA
× SYAHREZA, SAIDINA ANGKASA
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| 内容記述（抄録） | ||||||||
| 内容記述タイプ | Other | |||||||
| 内容記述 | Tangkuban Parahu volcano is one of the most active volcanoes in West Java, Indonesia, although most of the recent eruptions were relatively mild (e.g., 2013 eruption). However, there is still little information from the volcanic products in the proximal area. Here, we provide new documentation from the proximal volcanic succession, including tephra-stratigraphy, componentry analysis, and petrography of volcanic products. Detailed mapping of the proximal area shows that the volcanic products are predominantly composed of an alternation fine-clay and coarse ash, lapilli tuff, and pyroclastic breccia within 10 tephra units. Componentry of ash particles revealed the presence of five components, which associated with hydrothermally altered lithics, oxidized lithics, coherent crystalline lithics, magmatic juvenile and free crystal in entire eruptive products. These indicate that the subvolcanic hydrothermal system has been developed since the Holocene and associated with a continual introduction of magmatic intrusion. Petrographic observation shows the hydrothermal minerals of quartz or silica accompanied by alunite and kaolinite, which represents acidic alteration within the crater-conduit. The presence of the silicified zone indicates that the subvolcanic hydrothermal system plays an essential role as a cap-rock of pressurized gas and steam at depth (200-500m), whereas magmatic injection caused the vapor plume expansion. Our observation concluded that the proximal volcanic succession captured the evidence of coupled phreatic and phreatomagmatic activities during the latest development of Mt.Tangkuban Parahu. In order to understand the subvolcanic hydrothermal system condition, we carried out the mineralogy and sulfur isotopic signature of volcanic products from the proximal area of Tangkuban Parahu volcano. X-ray diffraction analysis reveals the majority of the hydrothermal mineral constituent. Silica polymorph (quartz, cristobalite, and tridymite) and alunite are dominant, whereas kaolinite randomly presents in some stratigraphic sections. Jarosite and goethite are abundant in the upper section of composite stratigraphy. The temporal mineralogical changing could reflect the depth of explosion or hydrothermal alteration development below the active craters, where some jarosite and possibly represent highly oxidized conditions after the emplacement process. From petrographic observation, hydrothermally altered lithics consist of two primary ash particle types; 1) partly altered magmatic glass and 2) selectively to pervasively altered ash fraction. The later ash particles comprise four types hydrothermal mineral assemblages along with two evidence of hydrothermal veinlet feeders. Hydrothermal mineral assemblages are opal, opal + cristobalite + alunite ± kaolinite, quartz + alunite ± kaolinite, and oxidation of alunite + jarosite, whereas the veinlets are silica+alunite-kaolinite-goethite±APS and quartz-pyrite. The accessory minerals (pyrite, chalcopyrite, and enargite) also present in many ash particles. These alteration assemblages are classified as acid-sulfate alteration and argillic alteration, which mostly present at near-surface of geothermal field in calcalkaline stratovolcanoes. Their presence also possibly rooted in high-temperature magmatic-vapor zone underneath the volcano. |
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| 著者版フラグ | ||||||||
| 出版タイプ | VoR | |||||||
| 出版タイプResource | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |||||||
| 書誌情報 | 発行日 2019-09-26 | |||||||
| 出版者 | ||||||||
| 出版者 | 秋田大学 | |||||||
| 学位名 | ||||||||
| 学位名 | 博士（理学） | |||||||
| 学位授与機関 | ||||||||
| 学位授与機関識別子Scheme | kakenhi | |||||||
| 学位授与機関識別子 | 11401 | |||||||
| 学位授与機関名 | 秋田大学 | |||||||
| 学位授与年月日 | ||||||||
| 学位授与年月日 | 2019-09-26 | |||||||
| 学位授与番号 | ||||||||
| 学位授与番号 | 甲第1312号 | |||||||
