Constraints on volumes and patterns of asthenospheric melt from the space‐time distribution of seamounts
Constraints on volumes and patterns of asthenospheric melt from the space‐time distribution of seamounts
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DOI：
10.1002/2017gl074098
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发表时间：
2017-07
影响因子：
5.2
通讯作者：
C. Conrad;K. Selway;M. Hirschmann;M. Ballmer;P. Wessel
中科院分区：
文献类型：
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作者：
C. Conrad;K. Selway;M. Hirschmann;M. Ballmer;P. Wessel
尽管软流圈的部分熔融在地球动力学上是重要的，但对其丰度的地球物理限制仍然是模糊的。我们使用卫星测高探测到的海山数据库来限制软流层融化喷发的时间历史。我们发现年轻海底(<；60 Ma)上的板内火山作用相当于横跨海底的~20m厚的一层。如果这些海山在海脊两侧下方约20公里厚的层内形成部分熔融，则表明平均熔融比例为~0.1%。如果它们产生更薄的层或更横向受限的区域，则需要更大的熔体比例。较老岩石圈海山体积的增加表明，白垩纪期间海脊侧翼火山活动更加活跃，或者较老海底最近发生了额外的熔融喷发。太平洋盆地年龄的限制表明，这两个过程都很重要。我们的结果表明，在横跨大洋盆地的软流层上部，可能存在少量的部分熔融。
Although partial melt in the asthenosphere is important geodynamically, geophysical constraints on its abundance remain ambiguous. We use a database of seamounts detected using satellite altimetry to constrain the temporal history of erupted asthenospheric melt. We find that intraplate volcanism on young seafloor (<60 Ma) equates to a ~20 m thick layer spread across the seafloor. If these seamounts tap partial melt within a ~20 km thick layer beneath the ridge flanks, they indicate extraction of an average melt fraction of ~0.1%. If they source thinner layers or more laterally restricted domains, larger melt fractions are required. Increased seamount volumes for older lithosphere suggest either more active ridge flank volcanism during the Cretaceous or additional recent melt eruption on older seafloor. Pacific basin age constraints suggest that both processes are important. Our results indicate that small volumes of partial melt may be prevalent in the upper asthenosphere across ocean basins.