Crustal Formation on a Spreading Ridge Above a Mantle Plume: Receiver Function Imaging of the Icelandic Crust
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Publication Date
2018Journal Title
Journal of Geophysical Research: Solid Earth
ISSN
2169-9313
Publisher
American Geophysical Union (AGU)
Volume
123
Issue
6
Pages
5190-5208
Type
Article
Metadata
Show full item recordCitation
Jenkins, J., Maclennan, J., Green, R., Cottaar, S., Deuss, A., & White, R. (2018). Crustal Formation on a Spreading Ridge Above a Mantle Plume: Receiver Function Imaging of the Icelandic Crust. Journal of Geophysical Research: Solid Earth, 123 (6), 5190-5208. https://doi.org/10.1029/2017JB015121
Abstract
Iceland sits astride a mid-ocean ridge underlain by a {mantle} hotspot. The interplay of these two geological processes has the potential to generate a complex and laterally variable crustal structure. The thickness of the Icelandic crust is a long running and controversial debate, with estimates ranging from a "thin'' 20 km crust to a "thick'' 40 km crust. We present new images of the first order seismic discontinuity structure of the Icelandic crust based on a joint inversion of receiver function and ambient noise derived surface wave dispersion data. Inversion results are validated through comparison to receiver functions multi-phase common conversion point stacks across the densely instrumented Northern Volcanic Zone. We find a multi-layered crustal structure consisting of a 6-10 km deep upper crust underlain by either one or two discontinuities. The shallower discontinuity is found at depths of ~20 km throughout Iceland. The deeper discontinuity is only present in some regions, defining the base of a lens-like lower layer with maximum depths of 44 km above the center of the mantle plume. Either of these two discontinuities could be interpreted as the seismic Moho, providing an explanation why previous estimates of crustal thickness have diverged. Such structure may form via underplating of a pre-existing oceanic crust as has been hypothesized in other ocean island plume settings. However we demonstrate with a simple petrological model that variability in seismic discontinuity structure can also be understood as a consequence of compositional variation in melts generated with distance from the plume center.
Sponsorship
European Commission (308377)
Natural Environment Research Council (NE/H025006/1)
Identifiers
External DOI: https://doi.org/10.1029/2017JB015121
This record's URL: https://www.repository.cam.ac.uk/handle/1810/279760
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