Estimation of time scale for magma intrusion by multiple dykes

多岩脉岩浆侵入的时间尺度估计

• 批准号: 07804032
• 负责人: UMINO Susumu
• 金额: $ 1.41万
• 依托单位: Shizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07804032/
• 关键词: multiple dyke; sheeted dykes; dyke; intrusion; Fudeshima Volcano; Troodos Ophiolite; Semail Ophiolite; magma chmber

Conclusions : Most significant knowledge obtained through the research is as follows ;(1) Multiply chilled-margin dykes(2) Conditions of multiple dyke formation(3) Multiple dykes are common in arc volcanoes and slow spreading ridges, while they may be rare in fast spreading ridges.Multiply chilled-margin dykes : Field research done on Fudeshima Volcano, Izu Oshima, Older volcanics of northern Yatsugatake Volcano and Troodos Ophiolite, Cyprus, revealed the existence of a sort of multiple dykes, which have multiply chilled margins 1-20 cm thick only in several tens of centimeters from the dyke selvages. Such dykes indicate that pulse of magma intrusions repeated in a short time interval.Conditions of multiple dyke formation : In Troodos Ophiolite, Presence of multiple dykes are confined to near the layred gabbros. On the contrary, sheeted dykes occurring in stratigraphically higher horizons are of simple dykes. This suggests the conditions which favor the formation of multiple dykes to be 1) repetition of magma intrusion, and 2) large ratios of frequency of magma intrusion/solidification time of dykes (F/S ratio).Troodos vs. Semail : All sheeted dykes examined in the Semail Ophiolite are simple. This suggests that in Semail, 1) magma did not intrude as pulse, or 2) F/S ratio was very high. In addition to this, generation of magma pulse may be controlled by the ratio of volume of recharged magma/that of magma chamber.

结论：通过研究获得的最重要的知识如下：（1）多重冷缘堤坝（2）多重堤坝的形成条件（3）多重堤坝在弧火山和缓慢扩张的山脊中常见，而在快速扩张的山脊。多重冷缘堤坝：对笔岛火山、伊豆大岛、八岳北部的古老火山进行的实地研究塞浦路斯的火山和特罗多斯蛇绿岩揭示了一种多重堤坝的存在，这些堤坝具有多个1-20厘米厚的冷边缘，距堤坝边缘仅几十厘米。这种岩脉表明岩浆侵入脉冲在很短的时间间隔内重复出现。多重岩脉的形成条件：在特罗多斯蛇绿岩中，多重岩脉的存在仅限于层状辉长岩附近。相反，出现在地层较高层的片状岩脉是简单岩脉。这表明有利于形成多重岩脉的条件是：1）岩浆侵入的重复，以及2）岩浆侵入频率/岩脉凝固时间的较大比率（F/S比）。Troodos vs. Semail：所有片状岩脉在Semail Ophiolite 中检查很简单。这表明在Semail中，1）岩浆没有以脉冲形式侵入，或者2）F/S比非常高。除此之外，岩浆脉冲的产生可以通过再充填的岩浆的体积/岩浆室的体积的比率来控制。

项目成果

Umino, S.: "Geochemical segmentation of sheeted dykes of the Troodos paleospreading centre" Repts. Fac. Sci., Shizuoka Univ.31. 45-66 (1997)

Umino, S.：“特罗多斯古扩张中心片状堤坝的地球化学分割” Repts。

Umino, S.and Mochizuki, A.: "Geochemical segmentation of sheeted dykes of the Troodos paleospreading center." Repts.Fac.Sci., Shizuoka Univ.31. 45-66 (1997)

Umino, S. 和 Mochizuki, A.：“特罗多斯古扩张中心片状堤坝的地球化学分割。”

Umino,S.: "Geochemical segmentation of sheeted dykes of the Troodos paleospreading centre." Repts.Fac.Sci.,Shizuoka Univ.31. 45-66 (1997)

Umino,S.：“特罗多斯古扩张中心片状堤坝的地球化学分割。”

Umino, S.: "Geology of the Semail Ophiolite, northern Oman mountins (in Japanese)." J.Geogr.104. 321-349 (1995)

Umino, S.：“阿曼北部山脉 Semail 蛇绿岩的地质学（日语）。”

海野 進: "北部オマーン山脈 サマイル・オフィオライトの地質" 地学雑誌. 104. 321-349 (1995)

Susumu Unno：“阿曼北部山区萨迈尔蛇绿岩的地质学”地质杂志 104. 321-349 (1995)。