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TitleEvidence for asymmetric accretion and low-angle, planar faults in slow-spreading oceanic crust
AuthorCollier, J S; Dañobeitia, J J; Canales, J -P; Dalwood, R; Gadd, S; Hayward, N; Henstock, T; Krastel, S; Peirce, C; Watts, A
SourceGeology vol. 25, no. 12, 1997 p. 1075-1078,<1075:efaaal>;2
Alt SeriesEarth Sciences Sector, Contribution Series 20090296
PublisherGeological Society of America
Mediapaper; on-line; digital
File formatpdf
AreaAtlantic Ocean
Lat/Long WENS-25.0000 -18.0000 31.0000 25.0000
Subjectsgeophysics; oceanic crust; oceanic lithosphere; seismic surveys, marine; seismic reflection surveys; seismic interpretations; geophysical surveys; seafloor topography; seabottom topography; sea floor spreading; Mesozoic
Illustrationslocation maps; block diagrams; profiles
AbstractNew seismic reflection data in the eastern Atlantic have enabled two large-scale dipping reflectors imaged within Mesozoic ocean crust to be mapped in three dimensions and placed in their sea-floor-spreading context. One of the reflectors dips to the west and extends from a step in the igneous basement to the Moho. The other reflector dips to the east and extends between 4 and 10 km below basement. Both reflectors are oriented approximately parallel to isochrons, lie just north of a 5-km-offset, third-order discontinuity, are planar in cross section, and dip at ~30°. We interpret both these reflectors as lithospheric-scale faults formed within the median valley at the axis. We suggest that the lower part of the eastward-dipping fault was "captured" from the North American plate, possibly by rapid propagation of an active volcanic rift across the discontinuity.