著者
生田 正文 丹羽 正和 檀原 徹 山下 透 丸山 誠史 鎌滝 孝信 小林 哲夫 黒澤 英樹 國分(齋藤) 陽子 平田 岳史
出版者
一般社団法人 日本地質学会
雑誌
地質学雑誌 (ISSN:00167630)
巻号頁・発行日
vol.122, no.3, pp.89-107, 2016-03-15 (Released:2016-06-21)
参考文献数
67
被引用文献数
11

既往文献の火山ガラス屈折率データからは識別が困難であった桜島の歴史時代の噴火(文明,安永,大正)軽石について,本研究では火山ガラスの水和部と未水和部とを区別して屈折率測定を行い,斜方輝石の屈折率も含めてそれぞれの軽石に違いがあることを見出した.一方,宮崎平野南部で掘削したコアに含まれる軽石濃集層に対して鉱物組成分析,火山ガラスの形態分類や屈折率測定,斜方輝石の屈折率測定,および炭質物の放射性炭素年代測定を行い,本研究による歴史時代の桜島噴火起源の軽石の分析と比較した.また,それぞれの火山ガラスについてレーザーアブレーション誘導結合プラズマ質量分析法による主成分・微量元素同時分析を行った.その結果,軽石濃集層は桜島文明テフラに対比されることが判明した.桜島文明テフラは,軽石の状態で宮崎平野南部まで到達していた可能性が高い.
著者
横瀬 久芳 小林 哲夫 長岡 信治
出版者
熊本大学
雑誌
基盤研究(B)
巻号頁・発行日
2007

琉球弧北部のトカラ列島における火山活動の実態解明を目的に,ドレッジを用いた海底調査を実施した。海底より回収された火山岩類は,海面下にも第四紀火山活動が広く分布していることを示す。特に,海底カルデラ地形の近傍では,現地性流紋岩質軽石が確認でき,トカラ列島における巨大海底カルデラの存在を強く示唆する。火山岩類の地球化学的特徴から,北部琉球弧の火山活動や鉱床形成過程は,沈み込むフィリピン海プレートの形状によって支配されている事が判明した。
著者
小林 哲夫
出版者
特定非営利活動法人日本火山学会
雑誌
火山. 第2集 (ISSN:04534360)
巻号頁・発行日
vol.27, no.4, pp.277-292, 1982-12-28
被引用文献数
12

Sakurajima Volcano consists of two main stratovolcanoes, Kitadake and Minamidake, which are composed of pyroclastic rocks and lava flows of pyroxene andesites and dacites. The basement rocks are composed of sedimentary rocks such as shale, sandstone, and acidic tuff, welded tuff, and granitic rocks. Geomorphology, large-scale historic eruptions, and the classification of surface textures of andesitic lava flows are briefly summarized. Volcanic history on the basis of the correlation between tephrochronology and the welded pyroclastic deposits is also presented. Taisho and An-ei lavas extruded at the later stage of the eruptions contain microphenocrysts of olivine. Orthopyroxenes of Bunmei pumice of later stage are rich in En content than those of early stage. These facts suggest that the volcanic products of the large eruptions were derived from zoned magma chambers.
著者
長谷川 健 柴田 翔平 小林 哲夫 望月 伸竜 中川 光弘 岸本 博志
出版者
特定非営利活動法人 日本火山学会
雑誌
火山 (ISSN:04534360)
巻号頁・発行日
vol.66, no.3, pp.187-210, 2021-09-30 (Released:2021-10-29)
参考文献数
57

Based on detailed fieldwork, petrological and paleomagnetic investigations, we present a revised stratigraphy of deposits from the 7.6 ka eruption at Mashu volcano and the formation process of its summit caldera, eastern Hokkaido, Japan. As previously described, the eruption products consist of an initial phreatomagmatic unit (Ma-j) and the overlying three pumice-fall layers (Ma-i, -h, and -g), which are in turn overlain by pyroclastic-flow deposits (Ma-f). In the present study, we divide Ma-f into 4 subunits: Ma-f1/2, Ma-fAc, Ma-f3a and Ma-f3b in descending order. Ma-f3b is a valley-ponding, pumice-flow deposit with limited distribution. Ma-f3a comprises clast-supported facies (fines-depleted ignimbrite: FDI) and matrix-supported (normal ignimbrite) facies, the two changing across topography. The FDI is characterized by a gray, fines-depleted, lithic-breccia-rich layer with materials incorporated from the substrate. Impact sag structures from large (>50 cm) dacite ballistic blocks were recognized at the base of the Ma-f3a within 10 km from the source. Ma-fAc is a minor eruption unit consisting of accretionary lapilli. Ma-f1/2 is a most voluminous (8.8 km3), widely distributed and weakly stratified ignimbrite. Both Ma-f3a and Ma-f1/2 can be classified as “low aspect ratio ignimbrite (LARI)”. Dacite lithic fragments are ubiquitously observed throughout the sequence and are not considered to be juvenile; they have distinctly different chemical compositions from the pumice fragments in the early pumice-fall (Ma-g~Ma-i) and pyroclastic-flow (Ma-f3b) deposits, but those of pumice clasts in the late pyroclastic-flow units (Ma-f3a and Ma-f2) lie between the two on a FeO*/MgO vs. SiO2 diagram. The 7.6 ka caldera-forming eruption of the Mashu volcano was initiated by Plinian fall (Ma-j~-g), and then, a small-volume high aspect ratio ignimbrite (Ma-f3b) was deposited by a valley-confined pyroclastic flow that was generated by partial column collapse. After that, a violent pyroclastic flow was generated probably during a strong explosion of a dacite lava edifice on the summit of Mashu volcano. This flow emplaced Ma-f3a. The caldera collapse that followed the explosion generated a climactic pyroclastic flow that emplaced Ma-f1/2. Ma-f3a flow was extremely fast. Ma-f1/2 flow was related to sustained flow due to low settling velocity and high discharge volume. These are supported by field observations and numerical simulation that shows the ability of the flow to surmount high topographic obstacles and spread widely. The 7.6 ka caldera-forming process of Mashu volcano was driven not only by subsidence of roof block but also by violent explosions.
著者
藤野 直樹 小林 哲夫
出版者
特定非営利活動法人 日本火山学会
雑誌
火山 (ISSN:04534360)
巻号頁・発行日
vol.42, no.3, pp.195-211, 1997-06-30 (Released:2017-03-20)
参考文献数
26
被引用文献数
3

Kaimondake Volcano, situated in the Ibusuki Volcanic Region of southern Kyushu, is an undissected volcano which consists of a basal stratovolcano and a small central volcano. We established the eruptive history of this volcano by tephrochronology. Kaimondake Volcano started its eruption ca. 4 ka, and the latest eruption occurred in A. D. 885 (ca. 1.1ka). For about 2,900 years during this period, the volcano had been active, and 12 major eruption deposits (Km 1-Km 12) were recognized. The repose periods between these eruptions were estimated to range from 100 to 400 years. The mode of eruption of this volcano was mainly scoriaceous sub-plinian type, and was frequently associated with phreatomagmatic eruptions because the volcano originated from the shallow sea or near-shore environment. Lava flows were often associated with the scoria eruptions. Submarine lava flows which flowed southeastward are topographically divided into three; among them the lowest one is the most voluminous and is thought to have flowed out in the early stage, probably before Km6 eruption period. Among the 12 major eruption deposits, Km1, Km9 (ca. 2 ka), Km11 (ca. 1.5 ka), and Km12 (ca. 1.1 ka) were voluminous, and largely contributed to the formation of the volcanic edifice. During the latest eruption (Km 12), a central volcano was formed in the summit crater. This central volcano is not a simple lava dome, but a mound of complex volcanic materials with a composite structure. It consists of a basal scoria cone associated with fluid lava flows, which is later capped by viscous lava dome, and then subsequently penetrated by volcanic plug around the summit. The summit crater, which is named Hachikubo, had been thought to be a collapse crater, but it was geologically proved to be a large explosion crater which was successively enlarged during the eruption of Km12a. The total amount of volcanic products was calculated to be 3.1 km3 and 2.3 km3 for tephra and lava flows, respectively. Although there are no systematic relations between eruption volumes and the preceding repose period, the eruption materials containing tephra were more voluminous in the later stage than in the early stage, while those of lava flows were exceptionally large in the early stage of volcanic history.
著者
早川 由紀夫 荒牧 重雄 白尾 元理 小林 哲夫 徳田 安伸 津久井 雅志 加藤 隆 高田 亮 小屋口 剛博 小山 真人 藤井 敏嗣 大島 治 曽屋 龍典 宇都 浩三
出版者
特定非営利活動法人日本火山学会
雑誌
火山. 第2集 (ISSN:04534360)
巻号頁・発行日
vol.29, pp.S208-S220, 1984-12-28

Stratigraphy and thickness distribution of the pyroclastic fall deposits formed during the eruption of Miyakejima volcano on October 3-4, 1983, were studied immediately after the deposition. Of the total mass of 20 million tons erupted, 8.5 million tons were ejected as basaltic scoria to form a complex set of air-fall deposits east of the fissure vents. One million tons of the latter were ejected from the upper fissures as fire-fountain products. The rest was the product of phreatomagmatic explosions which occurred in the lower fissures where ground water chilled the magma to form dense scoria blocks which devastated villages. Explosion craters and a tuff ring were formed along the N-S trending lower fissures. Account of the general distribution of the deposits, nature of the constituents, mutual stratigraphic correlation and correlation with observed sequence are given.
著者
國武 絵美 小林 哲夫
出版者
公益社団法人 日本農芸化学会
雑誌
化学と生物 (ISSN:0453073X)
巻号頁・発行日
vol.57, no.9, pp.532-540, 2019-09-01 (Released:2020-09-01)
参考文献数
45

糸状菌(いわゆるカビ)は生育環境中に存在するさまざまな多糖を分解してエネルギー源として利用する.近年,それぞれの多糖の分解酵素遺伝子に特異的な転写活性化因子が次々と同定され,その転写誘導メカニズムの全容も明らかになりつつある.一方でグルコースのような資化しやすい糖存在下で起こるカタボライト抑制では従来の転写抑制因子がかかわる経路とは別の新奇経路が見いだされ,この経路の関与の程度が多糖分解酵素の種類によって異なることが判明した.本稿ではこれらの転写制御機構を介して糸状菌がどのように利用する糖質の優先順位を決定づけているのかについて考察する.
著者
成尾 英仁 小林 哲夫
出版者
日本第四紀学会
雑誌
第四紀研究 (ISSN:04182642)
巻号頁・発行日
vol.41, no.4, pp.287-299, 2002-08-01
参考文献数
37
被引用文献数
5 11

薩摩・大隅半島南半部と南方海域に位置する種子島・屋久島において,6.5ka BPに鬼界カルデラで発生したアカホヤ噴火に伴った地震の痕跡が多数見つかった.地震の痕跡は,薩摩・大隅半島南半部では砂や軽石・シルトが噴き出す噴砂脈であるが,種子島・屋久島では礫が噴き出した噴礫脈である.噴砂脈は薩摩半島中南部と大隅半島中部のシラス台地上に集中しており,シラス(入戸火砕流堆積物:A-Ito)の二次堆積物から発生するものが主体である.一方,噴礫脈は種子島・屋久島の海岸段丘面上に存在しており,礫に富む段丘堆積物から派生したものと,基盤をつくる熊毛層群の風化・破砕された礫から発生したものとがある.<br>これら噴砂・噴礫脈の発生時期であるが,種子島・屋久島地域での噴礫の発生は火砕流噴火の直前~同時期の1度だけであったが,薩摩・大隅半島南半部での噴砂は噴礫の発生と同時期だけでなく,鬼界アカホヤ火山灰(K-Ah)の降下中にも発生した.<br>すなわち,最初の巨大地震は,種子島・屋久島地域から薩摩・大隅半島南半部にわたる広い範囲で噴礫・噴砂を発生させたが,2度目の地震は数時間ほど後に発生し,震源はより北部に移動した可能性が大きい.