The Miocene Galápagos ash layer record of integrated ocean drilling program legs 334 and 344: ocean-island explosive volcanism during plume-ridge interaction
The Miocene Galápagos ash layer record of integrated ocean drilling program legs 334 and 344: ocean-island explosive volcanism during plume-ridge interaction
复制标题
DOI：
10.1130/g36645.1
复制
发表时间：
2015-07
期刊：
影响因子：
5.8
通讯作者：
J. Schindlbeck;S. Kutterolf;A. Freundt;S. Straub;Kuo‐Lung Wang;M. Jegen;S. Hemming;A. Baxter;M. I. Sandoval
中科院分区：
文献类型：
--
作者：
J. Schindlbeck;S. Kutterolf;A. Freundt;S. Straub;Kuo‐Lung Wang;M. Jegen;S. Hemming;A. Baxter;M. I. Sandoval
在哥斯达黎加近海Cocos Ridge的综合海洋钻探计划站点U1381进行钻探，恢复了67个初级中新世（约8 Ma至约16.5 Ma）海洋沉降灰层。地球化学、火山学和地质标准将这些火山灰与普林尼火山喷发联系起来，这些火山喷发将火山灰带到离加拉帕戈斯热点至少50-450公里的地方。这些火山灰层是高爆炸性中新世加拉帕戈斯群岛热点火山活动的第一个记录。这种火山作用是双峰的，三分之二的火山层由玄武岩岩浆（玻璃成分SiO2 <57 wt%）产生，三分之一由流纹岩岩浆产生。根据40Ar/39Ar和生物地层年龄校准的沉积速率推断，tephra层的时间分布表明，在14ma之后，喷发频率明显增加，因此加拉帕戈斯热点的火山活动增加，我们在加拉帕戈斯羽流和扩张脊之间的动态相互作用背景下解释了这一点。
Drilling at Integrated Ocean Drilling Program Site U1381 on the Cocos Ridge offshore Costa Rica recovered 67 primary Miocene (ca. 8 Ma to ca. 16.5 Ma) marine fallout ash layers. Geochemical, volcanological, and geological criteria link these ashes to Plinian eruptions that carried ash to at least 50–450 km from the Galapagos hotspot. These ash layers are the first documentation of highly explosive Miocene Galapagos hotspot volcanism. This volcanism is bimodal with two-thirds of the tephra layers generated by basaltic magmas (glass compositions <57 wt% SiO2) and one-third by rhyolitic magmas. The temporal distribution of the tephra layers, inferred from sediment accumulation rates calibrated by 40Ar/39Ar and biostratigraphic ages, reveals a distinct increase in eruption frequency and hence increased volcanic activity of the Galapagos hotspot after 14 Ma which we interpret in the context of dynamic interaction between the Galapagos plume and spreading ridge.