Mendeley出力
＜紀要論文＞
本邦の火山について
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| 概要 | 1. The Tertiary volcanic rocks as well as the Quaternary volcanic rocks in the inner side of the Japan Islands Arc generally have lower alkali-lime index than those of the outer side (Figs. 1 and 2) 2.... The Quaternary volcanic rocks are more calcic (higher in the alkali-lime index) than the Tertiary volcanic rocks, in the average chemical compositions. The lavas of historic times are most calcic (highest in A. L. 1.) of the Quaternary volcanics (Tables 10 and 12) 3. The Quaternary volcanic rocks are poorer in H心andFe20s (compared with FeO) than the Tertiary volcanic rocks. Of the Quaternary volcanics, the lavas of historic times are poorest in HゆandFe20s (Table 10 and Figs. 3-8). 4. The frequency curves are asymmetric and appear to be a combination of several symmetric frequency curves. It is to be noted that (1) the curves are characterized by three principal peaks (basaltic, andesitic and rhyolitic peaks), (2) the basaltic peak is most basic for the Tertiary volcanic rocks and most acidic for the lavas of historic times, while the rhyolitic peak is most acidic for the Tertiary volcanic rocks and most basic for the lavas of historic tirp.es (Table 11 and Fig. 10) and (3) the basaltic peak is most distinctive for the lavas of historic times (Table 12, Figs. 11 and 15). Such a convergence of magma in the chemical compostions as mentioned above, should be noticed on geological and petrological view points. 5. The frequency distribution of volcanoes based on the silica percentages of their products is well corresponding to the frequency distribution of their products (lavas), though the frequency peaks for the latter are more distinct than those for the former (Table 13 and Figs. 13 and 14). It seems to be true that the more active magma erupts more frequently and at more number of volcanoes than the less active magma. 6. It may be properly concluded that the comparatively less-alkalic (tholeiitic, calc-alkalic) agma have retained its activity through historic times in the middle and outer zones of the arcuate Japan Islands, a part of the Cainozoic orogenic zone. 7. The variation trend of the frequency distribution of the products should be available for estimating the fluctuation trend of magma activity. It may be presumed that basaltic lavas and slightly acid andesitic lavas should hold more steady activity than rhyolitic and comparatively basic andestitic lavas 8. If the fluctuation trend of magma activity throughout geologic times, as well as recent times, is clarified in details, it will be available for presuming or predicting the future volcanism (and possible eruption also on a certain good condition).続きを見る |
| 目次 | 1. まえがき 2. 研究の経過 3. 研究の主テーマ 4. 新生代火山岩類の分類 5. 各集団の平均化学組成（相互の比較・変移 傾向の検討） 6. 熔岩類の頻度分布 7. 火山（活動）の頻度分布 8. アルカリ・石灰指数の変異傾向の検討 9. 頻度分布の変異傾向の検討 10. T. FeO-MgO-AlK関係に見られる傾向 11.結び続きを見る |
詳細
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| 登録日 | 2021.12.14 |
| 更新日 | 2022.06.20 |