Downward continued multichannel seismic refraction analysis of Atlantis Massif oceanic core complex, 30°N, Mid-Atlantic Ridge


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dc.contributor.author Henig, A. S.
dc.contributor.author Blackman, Donna K.
dc.contributor.author Harding, Alistair J.
dc.contributor.author Canales, J. Pablo
dc.contributor.author Kent, Graham M.
dc.date.accessioned 2012-06-20T16:18:27Z
dc.date.available 2012-11-19T09:41:07Z
dc.date.issued 2012-05-19
dc.identifier.citation Geochemistry Geophysics Geosystems 13 (2012): Q0AG07 en_US
dc.identifier.uri http://hdl.handle.net/1912/5232
dc.description Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 13 (2012): Q0AG07, doi:10.1029/2012GC004059. en_US
dc.description.abstract Detailed seismic refraction results show striking lateral and vertical variability of velocity structure within the Atlantis Massif oceanic core complex (OCC), contrasting notably with its conjugate ridge flank. Multichannel seismic (MCS) data are downward continued using the Synthetic On Bottom Experiment (SOBE) method, providing unprecedented detail in tomographic models of the P-wave velocity structure to subseafloor depths of up to 1.5 km. Velocities can vary up to 3 km/s over several hundred meters and unusually high velocities (~5 km/s) are found immediately beneath the seafloor in key regions. Correlation with in situ and dredged rock samples, video and records from submersible dives, and a 1.415 km drill core, allow us to infer dominant lithologies. A high velocity body(ies) found to shoal near to the seafloor in multiple locations is interpreted as gabbro and is displaced along isochrons within the OCC, indicating a propagating magmatic source as the origin for this pluton(s). The western two-thirds of the Southern Ridge is capped in serpentinite that may extend nearly to the base of our ray coverage. The distribution of inferred serpentinite indicates that the gabbroic pluton(s) was emplaced into a dominantly peridotitic host rock. Presumably the mantle host rock was later altered via seawater penetration along the detachment zone, which controlled development of the OCC. The asymmetric distribution of seismic velocities and morphology of Atlantis Massif are consistent with a detachment fault with a component of dip to the southeast. The lowest velocities observed atop the eastern Central Dome and conjugate crust are most likely volcanics. Here, an updated model of the magmatic and extensional faulting processes at Atlantis Massif is deduced from the seismic results, contributing more generally to understanding the processes controlling the formation of heterogeneous lithosphere at slow-rate spreading centers. en_US
dc.description.sponsorship NSF support was provided via grant OCE-0927442. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.uri http://dx.doi.org/10.1029/2012GC004059
dc.subject Mid-Atlantic Ridge en_US
dc.subject Detachment fault en_US
dc.subject Gabbro en_US
dc.subject Oceanic core complex en_US
dc.subject Seismic structure en_US
dc.subject Serpentinized peridotite en_US
dc.title Downward continued multichannel seismic refraction analysis of Atlantis Massif oceanic core complex, 30°N, Mid-Atlantic Ridge en_US
dc.type Article en_US
dc.description.embargo 2012-11-19 en_US
dc.identifier.doi 10.1029/2012GC004059

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