Why Does the Higashi-Izu Monogenetic Volcano Group Exist in the Izu Peninsula?
Why Does the Higashi-Izu Monogenetic Volcano Group Exist in the Izu Peninsula?
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伊豆半岛为何存在东伊豆单生火山群？
DOI：
10.4294/jpe1952.39.391
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
S. Umino
中科院分区：
文献类型：
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作者：
M. Koyama;S. Umino
综合现有的地质、岩石学和地球物理数据，建立了一个模型，用于解释晚第四纪火山活动（东伊豆单成因火山群，HIMVG）与日本伊豆半岛及其周围构造之间的关系。伊豆半岛及其邻近地区可划分为三个构造块体：西伊豆（W-伊豆）、东伊豆（E-伊豆）和大岛-善洲块体。HIMVG的喷口或侵入体形成为与E-Izu块体区域应力水平最大压缩的近NW-SE方位对齐的开放裂缝。该应力场主要受伊豆-小笠原弧与日本弧的强耦合作用所引起的北西-南东向挤压控制。尽管有这种挤压，但伊豆地块的上地壳在向东北伸展的侧向约束下很弱。无论是涉及板内断裂的板块几何形状，西相模湾断裂，并在北方伊豆块块体的块体旋转的存在可能使东北向上地壳伸展伊豆块体，并使一个单一的火山场，在那里一个新的岩墙形成在上地壳中的每一个喷发或侵入事件。
A synthesis of available geological, petrological, and geophysical data was made to construct a model for explaining the relationships between the late Quaternary volcanism (the Higashi-Izu monogenetic volcano group, HIMVG) and tectonics in and around the Izu Peninsula, Japan. The Izu Peninsula and adjacent areas can be divided into three tectonic blocks: the western Izu (W-Izu), eastern Izu (E-Izu), and Oshima-Zenisu blocks. The vents or intrusions of the HIMVG are formed as open cracks aligning with the nearly NW-SE azimuth of horizontal maximum compression of regional stress in the E-Izu block. This stress field is mainly controlled by the NW-SE compression caused by the strong mechanical coupling of the buoyant Izu-Bonin arc with the Japan arc. In spite of this compression, the upper crust of the E-Izu block is under weak lateral constraint on northeastward extension. Both the plate geometry involving an intra-plate fracture, the West Sagami Bay Fracture, and the existence of block rotations in the northern E-Izu block probably enable the northeastward upper crust extension in the E-Izu block, and make a monogenetic volcano field, where a new dike is formed in the upper crust at each eruptive or intrusive event.