Nonvolcanic seafloor spreading and corner-flow rotation accommodated by extensional faulting at 15°N on the Mid-Atlantic Ridge : a structural synthesis of ODP Leg 209

View/ Open
Date
2007-06-28Author
Schroeder, Timothy
Concept link
Cheadle, Michael J.
Concept link
Dick, Henry J. B.
Concept link
Faul, Ulrich
Concept link
Casey, John F.
Concept link
Kelemen, Peter B.
Concept link
Metadata
Show full item recordCitable URI
https://hdl.handle.net/1912/1791As published
https://doi.org/10.1029/2006GC001567Keyword
Seafloor spreading; Ocean Drilling Program; Nonvolcanic mid-ocean ridges; Extensional faultingAbstract
Drilling during ODP Leg 209, dredging, and submersible dives have delineated an anomalous stretch of the Mid-Atlantic Ridge north and south of the 15°20′N Fracture Zone. The seafloor here consists dominantly of mantle peridotite with gabbroic intrusions that in places is covered by a thin, discontinuous extrusive volcanic layer. Thick lithosphere (10–20 km) in this region inhibits magma from reaching shallow levels beneath the ridge axis, thereby causing plate accretion to be accommodated by extensional faulting rather than magmatism. The bathymetry and complex fault relations in the drill-core suggest that mantle denudation and spreading are accommodated by a combination of high-displacement, rolling-hinge normal faults and secondary lower-displacement normal faults. These extensional faults must also accommodate corner flow rotation (up to 90°) of the upwelling mantle within the shallow lithosphere, consistent with remnant magnetic inclinations in denuded peridotite and gabbro from Leg 209 core that indicate up to 90° of sub-Curie-temperature rotation.
Description
Author Posting. © American Geophysical Union, 2007. 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 8 (2007): Q06015, doi:10.1029/2006GC001567.
Collections
Suggested Citation
Geochemistry Geophysics Geosystems 8 (2007): Q06015Related items
Showing items related by title, author, creator and subject.
-
Fault rotation and core complex formation : significant processes in seafloor formation at slow-spreading mid-ocean ridges (Mid-Atlantic Ridge, 13°–15°N)
Smith, Deborah K.; Escartin, Javier E.; Schouten, Hans A.; Cann, Johnson R. (American Geophysical Union, 2008-03-05)The region of the Mid-Atlantic Ridge (MAR) between the Fifteen-Twenty and Marathon fracture zones displays the topographic characteristics of prevalent and vigorous tectonic extension. Normal faults show large amounts of ... -
Nonvolcanic tectonic islands in ancient and modern oceans
Palmiotto, Camilla; Corda, Laura; Ligi, Marco; Cipriani, Anna; Dick, Henry J. B.; Douville, Eric; Gasperini, Luca; Montagna, Paolo; Thil, Francois; Borsetti, Anna Maria; Balestra, Barbara; Bonatti, Enrico (John Wiley & Sons, 2013-10-24)Most oceanic islands are due to excess volcanism caused by thermal and/or compositional mantle melting anomalies. We call attention here to another class of oceanic islands, due not to volcanism but to vertical motions of ... -
ONR seafloor natural laboratories on slow- and fast-spreading mid-ocean ridges
Tucholke, Brian E.; Macdonald, Ken C.; Fox, Paul J. (American Geophysical Union, 1991-06-18)Long-term Natural Laboratories for in-depth studies of the seafloor at both a slowspreading (<30 mm/yr) and a fast-spreading (>60 mm/yr) mid-ocean ridge are being established by the Office of Naval Research. The two Natural ...