Increased rates of large-magnitude explosive eruptions in Japan in the late Neogene and Quaternary.
Increased rates of large-magnitude explosive eruptions in Japan in the late Neogene and Quaternary.
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DOI：
10.1002/2016gc006362
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发表时间：
2016-07
影响因子：
3.5
通讯作者：
Brown, S. K.
中科院分区：
文献类型：
--
作者：
Mahony, S. H.;Sparks, R. S. J.;Wallace, L. M.;Engwell, S. L.;Scourse, E. M.;Barnard, N. H.;Kandlbauer, J.;Brown, S. K.
科学海洋钻探的海洋沉积物岩心中的Tephra层在很大程度上记录了日本弧在过去2000万年中发生的高震级硅爆炸喷发。从一个全球数据集中对180个天火层的厚度随距离的变化进行分析，表明本研究中使用的大多数可见天火层都是(M) bbbb6级火山口形成喷发的产物，考虑到它们在各自钻探地点与可能的火山源的距离。岩心中可见温层的频率表明，在~ 8 Ma、6-4 Ma时，大震级爆发率显著增加，在~ 2 Ma后进一步增加。这些变化归因于构造板块相互作用的重大变化。中新世大震级爆发性火山活动的发生率较低，与菲律宾海板块和日本西南部之间的走滑主导边界（以及俯冲的暂时停止或减速）有关，再加上日本北部的大部分弧被淹没在海平面以下的可能性，部分原因是之前与日本海形成有关的本州北部的构造伸展。从~ 8 Ma到现在，板块运动和俯冲动力学的变化导致了(1)日本西南部弧正俯冲的增加（和弧火山活动的恢复）和(2)日本东北部上板块从伸展到压缩的转变，导致了隆起、地壳增厚，为爆炸性破火山口形成喷发所需的大量硅岩浆的积累创造了有利条件。日本远端沉积物岩心中~ 8、4-6和~ 2 Ma Tephra层火山活动的增加代表了6级或更大的喷发构造变化驱动了日本爆发火山活动的速率
Tephra layers in marine sediment cores from scientific ocean drilling largely record high‐magnitude silicic explosive eruptions in the Japan arc for up to the last 20 million years. Analysis of the thickness variation with distance of 180 tephra layers from a global data set suggests that the majority of the visible tephra layers used in this study are the products of caldera‐forming eruptions with magnitude (M) > 6, considering their distances at the respective drilling sites to their likely volcanic sources. Frequency of visible tephra layers in cores indicates a marked increase in rates of large magnitude explosive eruptions at ∼8 Ma, 6–4 Ma, and further increase after ∼2 Ma. These changes are attributed to major changes in tectonic plate interactions. Lower rates of large magnitude explosive volcanism in the Miocene are related to a strike‐slip‐dominated boundary (and temporary cessation or deceleration of subduction) between the Philippine Sea Plate and southwest Japan, combined with the possibility that much of the arc in northern Japan was submerged beneath sea level partly due to previous tectonic extension of northern Honshu related to formation of the Sea of Japan. Changes in plate motions and subduction dynamics during the ∼8 Ma to present period led to (1) increased arc‐normal subduction in southwest Japan (and resumption of arc volcanism) and (2) shift from extension to compression of the upper plate in northeast Japan, leading to uplift, crustal thickening and favorable conditions for accumulation of the large volumes of silicic magma needed for explosive caldera‐forming eruptions. Increase in volcanic activity in Japan at ∼8, 4–6, and ∼2 Ma Tephra layers in distal sediment cores represent magnitude 6 or greater eruptions Tectonic changes driving rates of explosive volcanism in Japan