K-Ar ages determined for post-caldera volcanic products from Aso volcano, central Kyushu, Japan
K-Ar ages determined for post-caldera volcanic products from Aso volcano, central Kyushu, Japan
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DOI：
10.1016/j.jvolgeores.2012.04.003
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发表时间：
2012-06-01
影响因子：
2.9
通讯作者：
Nagao, Keisuke
中科院分区：
文献类型：
--
作者：
Miyoshi, Masaya;Sumino, Hirochika;Nagao, Keisuke
本文采用无尖刺灵敏度法测定了日本九州中部阿索火山破火山口后熔岩的K-Ar年龄。在破火山口后阶段，可识别出70-50 ka、40-20 ka和10 ka以后的三个高频率火山活动高峰。70-50 ka和40-20 ka两个峰的岩浆活动特征为玄武岩-流纹岩组成多样。这些峰的硅质岩浆体积明显大于玄武岩岩浆体积。另一方面，10 ka以后的峰以玄武岩喷发为主，没有硅质岩浆活动。硅质岩浆的活动中心（=注入玄武岩的地壳同化）可能在70-50 ka和40-20 ka之间从火山口西南部向东北方向迁移。10 ka以后的玄武岩活动高峰表明硅质岩浆的生产速率下降，并不表明近期阿索火山口下有大量硅质岩浆的聚集。(C) 2012 Elsevier B.V.版权所有
We determined the K-Ar ages for post-caldera lavas from Aso volcano in central Kyushu, Japan using the unspiked sensitivity method. The following three peaks of highly-frequent volcanism are recognized in the post-caldera stage: 70-50 ka, 40-20 ka and later than 10 ka. The two peaks of 70-50 ka and 40-20 ka are characterized by activities of compositionally diverse magmas from basalt to rhyolite. The volumes of silicic magmas are significantly larger than those of basalt magmas in these peaks. On the other hand, the peak later than 10 ka is characterized by predominantly basaltic eruptions without silicic magma activities. The active center of the silicic magma production (=crustal assimilation of injected basalt) had presumably migrated northeastward from the southwestern part of the caldera between the peaks of 70-50 ka and 40-20 ka. The predominant basaltic activity in the peak later than 10 ka represents that the production rate of silicic magma decreased, and does not indicate the accumulation of voluminous silicic magma beneath the recent Aso caldera. (C) 2012 Elsevier B.V. All rights reserved.