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Heterogeneous seismic velocity structure of the upper lithosphere at Kane oceanic core complex, Mid-Atlantic Ridge

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dc.contributor.author Xu, Min
dc.contributor.author Canales, J. Pablo
dc.contributor.author Tucholke, Brian E.
dc.contributor.author DuBois, David L.
dc.date.accessioned 2010-04-21T19:17:02Z
dc.date.available 2010-04-21T19:17:02Z
dc.date.issued 2009-10-10
dc.identifier.citation Geochemistry Geophysics Geosystems 10 (2009): Q10001 en_US
dc.identifier.uri http://hdl.handle.net/1912/3297
dc.description Author Posting. © American Geophysical Union, 2009. 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 10 (2009): Q10001, doi:10.1029/2009GC002586. en_US
dc.description.abstract 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 refracted arrivals recorded along a 6-km-long hydrophone streamer during a multichannel seismic survey to constrain the shallow seismic velocity structure of the OCC. Results are presented in high-resolution traveltime seismic tomographic models along six lines that cover all of the main morphological features of the megamullion. The models show large lateral variability in P wave velocity within the upper ∼0.5–2.0 km of the lithosphere, and these variations correlate to first order with observed variations in lithology, documented by in situ basement samples and seafloor morphology. Lithological interpretation of the velocity models indicates that there is marked lateral variability in distribution of gabbroic intrusions, serpentinized peridotites, and basalts at scales of a few kilometers to ∼10 km. Serpentinized peridotites appear to dominate the central and older parts of the OCC. High-velocity gabbros are consistently (but not exclusively) present closer to the termination of the Kane detachment fault and toward the ends of the OCC. The structure of the lithosphere exhumed by the Kane detachment fault is far from the standard ophiolite-based Penrose model, and it does not show segment-centered magmatism that is commonly interpreted at slow spreading ridges. If the gabbros exhumed toward the termination of the OCC were emplaced deep (∼10 km) beneath the spreading axis, they may have constituted a weak zone that focused initiation of the Kane detachment fault. Alternately, as the OCC footwall was being exhumed the gabbros may have been emplaced because of dynamic changes in melt supply, changes in mantle fertility, or decompression melting. Late stage volcanism is clearly associated with a major high-angle normal fault that cuts the detachment surface; this volcanism may have been stimulated or enhanced by bending stresses in the bending footwall. The shape of the large-scale corrugated morphology of the OCC is nearly invariant in the dip direction across major changes in basement lithology, indicating that once established, the form of the Kane detachment fault was highly resistant to modification. en_US
dc.description.sponsorship This research was supported by NSF grants OCE-9987004 and OCE-0621660. 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/10.1029/2009GC002586
dc.subject Kane oceanic core complex en_US
dc.subject Ocean crustal structure en_US
dc.subject Detachment faulting en_US
dc.subject Mid-Atlantic Ridge en_US
dc.subject Seismic tomography en_US
dc.subject Lithology en_US
dc.title Heterogeneous seismic velocity structure of the upper lithosphere at Kane oceanic core complex, Mid-Atlantic Ridge en_US
dc.type Article en_US
dc.identifier.doi 10.1029/2009GC002586


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