Tephrostratigraphy and Provenance From IODP Expedition 352, Izu‐Bonin Arc: Tracing Tephra Sources and Volumes From the Oligocene to Recent
Tephrostratigraphy and Provenance From IODP Expedition 352, Izu‐Bonin Arc: Tracing Tephra Sources and Volumes From the Oligocene to Recent
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DOI：
10.1002/2017gc007100
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发表时间：
2017-12
期刊：
影响因子：
3.7
通讯作者：
S. Kutterolf;J. Schindlbeck;A. Robertson;A. Avery;A. Baxter;K. Petronotis;K.‐L. Wang
中科院分区：
文献类型：
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作者：
S. Kutterolf;J. Schindlbeck;A. Robertson;A. Avery;A. Baxter;K. Petronotis;K.‐L. Wang
对广泛分布的火山灰进行物源研究，并将其整合在一个明确的时间框架内，对于推断区域火山爆发的源头、规模、分布以及变化的系统性规律非常重要。在此，我们为综合大洋钻探计划352航次期间采集的总共157层海洋火山灰建立了一个可靠的火山灰年代地层学。我们推断在渐新世到更新世期间至少有三个主要的强烈火山爆发阶段。基于玻璃成分的物源分析将56层火山灰归为日本来源，包括与九州、日本中部和日本北部在11.5万年到350万年之间的个别火山爆发所产生的12层主要且广泛分布的火山灰层的关联。其余101层火山灰被归为沿着伊豆 - 小笠原弧的四个源区。其中一个源区仅对应渐新世，靠近小笠原群岛；两个源区反映了伊豆 - 小笠原弧中部火山前沿和弧后的火山爆发，第四个源区对应伊豆 - 小笠原弧北部源区。一级体积估算表明，与日本相关的火山爆发的喷发量级在6.3到7.6之间，伊豆 - 小笠原弧（IBM）火山爆发的喷发量级在5.5到6.5之间。我们的研究结果表明，3000万年到2200万年之间的火山灰与近期的伊豆 - 小笠原弧相比，具有略微不同的化学特征。在大约900万年的火山喷发间隔之后，从1500万年到500万年，伊豆 - 小笠原弧的火山灰供应占主导地位，最后在大约过去的500万年里，来自（古）本州和伊豆 - 小笠原弧的火山灰源大致等量混合。
Provenance studies of widely distributed tephras, integrated within a well‐defined temporal framework, are important to deduce systematic changes in the source, scale, distribution, and changes in regional explosive volcanism. Here, we establish a robust tephrochronostratigraphy for a total of 157 marine tephra layers collected during IODP Expedition 352. We infer at least three major phases of highly explosive volcanism during Oligocene to Pleistocene time. Provenance analysis based on glass composition assigns 56 of the tephras to a Japan source, including correlations with 12 major and widespread tephra layers resulting from individual eruptions in Kyushu, Central Japan, and North Japan between 115 ka and 3.5 Ma. The remaining 101 tephras are assigned to four source regions along the Izu‐Bonin arc. One, exclusively assigned to the Oligocene age, is proximal to the Bonin Ridge islands; two reflect eruptions within the volcanic front and back‐arc of the central Izu‐Bonin arc, and a fourth region corresponds to the Northern Izu‐Bonin arc source. First‐order volume estimates imply eruptive magnitudes ranging from 6.3 to 7.6 for Japan‐related eruptions and between 5.5 and 6.5 for IBM eruptions. Our results suggest tephras between 30 and 22 Ma reflect a subtly different Izu‐Bonin chemical signature compared to the recent arc. After a ∼9 Ma gap in eruption, tephra supply from the Izu‐Bonin arc predominated from 15 to 5 Ma, and finally a subequal mixture of tephra sources from the (palaeo)Honshu and Izu‐Bonin arcs occured within the last ∼5 Ma.