Spatial distribution and temporal evolution of crustal melt distribution beneath the East Pacific Rise at 9°–10°N inferred from 3‐D seafloor compliance modeling
Spatial distribution and temporal evolution of crustal melt distribution beneath the East Pacific Rise at 9°–10°N inferred from 3‐D seafloor compliance modeling
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根据 3D 海底柔度模型推断东太平洋海隆下方 9°–10°N 地壳熔体分布的空间分布和时间演化
DOI：
10.1002/2014jb011131
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
W. Crawford
中科院分区：
文献类型：
--
作者：
Y. Zha;S. Webb;S. Nooner;W. Crawford
确定洋中脊洋壳中的熔体分布对于了解岩浆如何在地壳中输送和安置至关重要。海底柔度（海浪强迫下的变形）主要对地壳中低剪切速度的区域敏感，使其成为探测熔体分布的有用工具。通过 3D 数值模型对在北纬 9° 至 10° 之间的东太平洋海隆收集的顺应性数据进行分析，揭示了下地壳剪切速度的强烈沿轴变化，以及 8 年测量之间北纬 9°48′附近地壳剪切速度的时间变化。在 9°48′N 和 9°33′N 处的上升轴上测量的柔度表明，脊轴下方存在深层地壳低速区，其低 Vs/Vp 比与低纵横比裂缝或基台中的熔体一致。 1999 年至 2007 年期间在北纬 9°48′处测得的顺应性变化表明，轴向地壳中的熔体分数在此期间有所下降，可能是在 2005 年至 2006 年海底喷发之后。这种时间变化为快速扩张的山脊处岩浆系统的短期变化提供了直接证据。
Determining the melt distribution in oceanic crust at mid‐ocean ridges is critical to understanding how magma is transported and emplaced in the crust. Seafloor compliance—deformation under ocean wave forcing—is primarily sensitive to regions of low shear velocity in the crust, making it a useful tool to probe melt distribution. Analysis of compliance data collected at East Pacific Rise between 9° and 10°N through 3‐D numerical modeling reveals strong along‐axis variations in the lower crustal shear velocities, as well as temporal variation of crustal shear velocity near 9°48′N between measurements spanning 8 years. Compliance measured across the rise axis at 9°48′N and 9°33′N suggest a deep crustal low‐velocity zone beneath the ridge axis, with a low Vs/Vp ratio consistent with melt in low aspect ratio cracks or sills. Changes in compliance measured at 9°48′N between years 1999 and 2007 suggest that the melt fraction in the axial crust decreased during this interval, perhaps following the 2005–2006 seafloor eruption. This temporal variability provides direct evidence for short‐term variations of the magmatic system at a fast spreading ridge.