Seismic structure of an oceanic core complex at the Mid-Atlantic Ridge, 22°19′N

Dannowski, Anke, Grevemeyer, Ingo, Ranero, Cesar R., Ceuleneer, Georges, Maia, Marcia, Morgan, Jason Phipps and Gente, Pascal (2010) Seismic structure of an oceanic core complex at the Mid-Atlantic Ridge, 22°19′N Journal of Geophysical Research - Solid Earth, 115 (B7). B07106. DOI 10.1029/2009JB006943.

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We present results from a seismic refraction and wide-angle experiment surveying an oceanic core complex on the Mid-Atlantic Ridge at 22°19′N. Oceanic core complexes are settings where petrological sampling found exposed lower crustal and upper mantle rocks, exhumed by asymmetric crustal accretion involving detachment faulting at magmatically starved ridge sections. Tomographic inversion of our seismic data yielded lateral variations of P wave velocity within the upper 3 to 4 km of the lithosphere across the median valley. A joint modeling procedure of seismic P wave travel times and marine gravity field data was used to constrain crustal thickness variations and the structure of the uppermost mantle. A gradual increase of seismic velocities from the median valley to the east is connected to aging of the oceanic crust, while a rapid change of seismic velocities at the western ridge flank indicates profound differences in lithology between conjugated ridge flanks, caused by un-roofing lower crust rocks. Under the core complex crust is approximately 40% thinner than in the median valley and under the conjugated eastern flank. Clear PmP reflections turning under the western ridge flank suggest the creation of a Moho boundary and hence continuous magmatic accretion during core complex formation.

Document Type: Article
Keywords: Meeresgeologie; Oceanic core complex; mid-ocean ridge; seismic tomography
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
DOI etc.: 10.1029/2009JB006943
ISSN: 0148-0227
Projects: Future Ocean
Date Deposited: 26 Aug 2010 08:30
Last Modified: 01 Feb 2017 09:08

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