Downward continued multichannel seismic refraction analysis of Atlantis Massif oceanic core complex, 30°N, Mid-Atlantic Ridge
Henig, A. S.
Blackman, Donna K.
Harding, Alistair J.
Canales, J. Pablo
Kent, Graham M.
MetadataShow full item record
KeywordMid-Atlantic Ridge; Detachment fault; Gabbro; Oceanic core complex; Seismic structure; Serpentinized peridotite
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.
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.
Suggested CitationArticle: Henig, A. S., Blackman, Donna K., Harding, Alistair J., Canales, J. Pablo, Kent, Graham M., "Downward continued multichannel seismic refraction analysis of Atlantis Massif oceanic core complex, 30°N, Mid-Atlantic Ridge", Geochemistry Geophysics Geosystems 13 (2012): Q0AG07, DOI:10.1029/2012GC004059, https://hdl.handle.net/1912/5232
Showing items related by title, author, creator and subject.
Heterogeneous seismic velocity structure of the upper lithosphere at Kane oceanic core complex, Mid-Atlantic Ridge Xu, Min; Canales, J. Pablo; Tucholke, Brian E.; DuBois, David L. (American Geophysical Union, 2009-10-10)The Kane oceanic core complex (OCC) is a large, corrugated megamullion that was formed by a long-lived detachment fault at the axis of the Mid-Atlantic Ridge adjacent to Kane Fracture Zone between 2.1 and 3.3 Ma. We use ...
Small-scale structure of the Kane oceanic core complex, Mid-Atlantic Ridge 23°30′N, from waveform tomography of multichannel seismic data Canales, J. Pablo (American Geophysical Union, 2010-11-03)Frequency-domain waveform tomography applied to deep-sea multichannel seismic data collected across the Kane oceanic core complex (OCC) reveals the small-scale structure of this section of oceanic lithosphere formed at the ...
Emplacement and high-temperature evolution of gabbros of the 16.5 degrees N oceanic core complexes (Mid-Atlantic Ridge): Insights into the compositional variability of the lower oceanic crust. Sanfilippo, Alessio; Dick, Henry JB; Marschall, Horst R.; Lissenberg, C. Johan; Urann, Ben (American Geophysical Union, 2018-12-05)This study reports the composition of the oceanic crust from the 16.5°N region of the Mid‐Atlantic Ridge, a spreading ridge segment characterized by a complex detachment fault system and three main oceanic core complexes ...