Network of off-axis melt bodies at the East Pacific Rise

被引：0
作者：
J. P. Canales
H. Carton
S. M. Carbotte
J. C. Mutter
M. R. Nedimović
M. Xu
O. Aghaei
M. Marjanović
K. Newman
机构：
[1] Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole
[2] Lamont-Doherty Earth Observatory, Columbia University, Palisades
[3] Department of Earth Sciences, Dalhousie University, Halifax
[4] Department of Geology and Geophysics, Massachusetts Institute of Technology, Woods Hole Oceanographic Institution, Woods Hole
来源：
Nature Geoscience | 2012年 / 5卷 / 4期
基金：
美国国家科学基金会;
关键词：
D O I：
10.1038/ngeo1377
中图分类号：
学科分类号：
摘要：
Magmatic accretion of new oceanic crust at intermediate- to fast-spreading mid-ocean ridges occurs along a narrow axial zone. This zone is characterized by molten sills in the crust that are emplaced within about 3 km of the ridge axis 1 and overlie a zone of elevated temperatures and partial melt 2-4. There are disparate indications of off-axis magmatism 5-8 and lavas erupted in the near-axis region are more compositionally variable than in the axial zone 9. Here we present three-dimensional seismic reflection images from the fast-spreading East Pacific Rise that reveal a network of sills 4 to 8 km east of the ridge axis. Our crustal model, constrained using seismic velocity and attenuation data, shows that the sills are located outside of the main axial zone of crustal accretion, and above a region containing partial melt. We infer that the sills represent sites of sustained off-axis magmatism. Pockets of melt extend from the off-axis sills to the axial zone and may represent melt migration pathways. These pathways could promote mixing between enriched off-axis melts and normal on-axis melts, contributing to the compositional variability of the near-axis lavas 9. We suggest that off-axis magmatism occurs preferentially, but not exclusively, where pre-existing fractures inherited from offsets of the spreading axis promote melt transport from the mantle into the crust. © 2012 Macmillan Publishers Limited. All rights reserved.
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页码：279 / 283
页数：4
相关论文
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