Nowacki, A orcid.org/0000-0001-7669-7383, Kendall, J-M and Wookey, J (2012) Mantle anisotropy beneath the Earth’s mid-ocean ridges. Earth and Planetary Science Letters, 317–318. pp. 56-67. ISSN 0012-821X
Abstract
Observations of seismic anisotropy at oceanic spreading centres offer insights into mid-ocean ridge processes and the formation of new plates. Here, remote observations of seismic anisotropy beneath mid-ocean ridges are made using measurements of source-side shear wave splitting. Over 100 high-quality measurements are made using earthquakes that occur near mid-ocean ridges and transform faults, but are observed at teleseismic distances. In general, for off-axis ridge events, the polarisation of fast shear waves, φ , is approximately parallel to the spreading direction. Nearer the ridge ( 50 km), φ becomes more scattered and is often ridge-parallel. Delay times, δt, tend to increase from <1 s near the ridge axis to ∼3 s further away. Slow-spreading regions (Gakkel and Southwest Indian Ridges) show smaller amounts of splitting than faster spreading centres. At transform zones, the pattern is more complex. Coverage beneath the East Pacific Rise is especially good, and we ob- serve a systematic increase in delay times in S wave splitting measurements compared to previous SKS splitting observations made at ocean-bottom seismometers. One compatible explanation is the presence of horizontally-aligned, connected layers of melt at depth; this is also compatible with other observations of the ‘LAB’ discontinuity and surface-wave derived measurements of radial anisotropy.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2011 Elsevier. This is an author produced version of a paper published in Earth and Planetary Science Letters. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | mid-ocean ridges; seismic anisotropy; LAB; mantle dynamics; LPO |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 09 May 2019 15:18 |
Last Modified: | 09 May 2019 15:18 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.epsl.2011.11.044 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:91919 |