Pacific offshore record of plinian arc volcanism in Central America: 2. Tephra volumes and erupted masses
Pacific offshore record of plinian arc volcanism in Central America: 2. Tephra volumes and erupted masses
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中美洲太平洋近海普林尼弧火山活动记录：2. 火山灰体积和喷发物
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发表时间：
2008
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影响因子：
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通讯作者：
W. Pérez
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作者：
S. Kutterolf;A. Freundt;W. Pérez
从中美洲近海的太平洋海底收集的沉积物重力岩心包含许多来自中美洲火山弧的plinian型喷发的远端灰层，可追溯到200 ka以上。在本文的第一部分中，我们将地核之间的许多火山灰层与陆地上的26个火山灰层进行了关联。海洋火山灰层覆盖了太平洋106平方公里的区域，占火山灰喷发量的主要部分（60-90%），因为太平洋海岸位于火山弧顺风几十公里的范围内。结合我们自己在陆地上的测绘工作和公布的测绘结果与我们的海洋数据产生的所有主要火山岩喷发卷沿着弧，范围从101至420立方公里。重新计算喷发的岩浆质量，广泛分布的火山岩占弧总岩浆输出量的65%。补充我们的火山灰数据与已发表的弧火山机构和火山年龄的卷，我们计算出每个火山的长期平均岩浆喷发率。此外，我们使用不相容元素的变化来计算累积的质量，在不同程度的分化分馏。这产生了每个火山长期平均岩浆产生速率的最小估计值，因为没有地表表达的侵入体和侵蚀损失没有考虑在内。从哥斯达黎加到危地马拉，岩浆的峰值生产率不断增加，但每个地区都有相当大的分散性，甚至在相邻的火山之间也有很大的差异。
Sediment gravity cores collected from the Pacific seafloor offshore Central America contain numerous distal ash layers from plinian‐type eruptions at the Central American Volcanic Arc dating back to more than 200 ka. In part 1 of this contribution we have correlated many of those ash layers between cores and with 26 tephras on land. The marine ash layers cover areas of up to 106 km2 in the Pacific Ocean and represent a major fraction (60–90%) of the erupted tephra volumes because the Pacific coast lies within a few tens of kilometers downwind from the volcanic arc. Combining our own mapping efforts on land and published mapping results with our marine data yields erupted volumes of all major tephras along the arc that range from ∼1 to 420 km3. Recalculated to erupted magma mass, the widespread tephras account for 65% of the total magma output at the arc. Complementing our tephra data with published volumes of the arc volcanic edifices and volcano ages, we calculate the long‐term average magma eruption rates for each volcano. Moreover, we use incompatible element variations to calculate the cumulate masses that were fractionated during variable degrees of differentiation. This yields a minimum estimate of long‐term average magma production rate at each volcano, because intrusives without surface expression and losses by erosion are not accounted for. Peak magma production rates increase from Costa Rica to Guatemala, but there is considerable scatter within each region and large differences even between neighboring volcanoes.