HR: 12:05h
AN: T12A-08    [Abstracts]
TI: Reconstruction of the Flanks of the Mid-Atlantic Ridge, $28\deg$ to $29\deg$ N: Implications for Evolution of Young Oceanic Lithosphere at Slow-Spreading Centers
AU: * Sloan, H
EM: heather.sloan@lehman.cuny.edu
AF: Lehman College City Univesity of New York, 250 Bedford Park Blvd West, Bronx, NY 10468 United States
AU: Patriat, P
EM: ppa@ipgp.jussieu.fr
AF: Institut de Physique du Globe, Bo\^{i}te 89 4 Place Jussieu, 75252 Paris, C\'{e}dex France
AB: We reconstruct the flanks of the Mid-Atlantic Ridge between $28\deg$ and $29\deg$ N from 1 to 10 Ma at intervals of 1 Myr for the purpose of investigating evolution of young oceanic lithosphere morphology and its variation through time using an innovative method that combines seafloor subsidence correction with interpolated isochrons and rotation poles. Reconstruction results are consistent with formation of abyssal hills every 1 to 2 Myr in 2-3 Myr old lithosphere at the outer edge of the ridge mountains as a result of transition from dynamic regime near the axis to isostatic regime of the flanks. The oblique passage of structures formed at the axial valley walls through this transition zone may play a role in the development of inside corner high bathymetry. Asymmetric juxtaposition of abyssal hill morphology in reconstruction is indicative of independent formation and evolution of the morphotectonic fabric on opposing flanks. The two major factors affecting asymmetric ridge flank morphology are found to be sense of axial offset and fluctuation of magmatic activity at the segment scale. Sense of axial offset determines the relative distribution of inside and outside corner bathymetry on the flanks. Enhanced magma supply and associated segment propagation may contribute to half-spreading rate asymmetry, accretion of thicker crust, and formation of larger abyssal hills on the faster-spreading flank. Consistent alignment in reconstruction of the base of the steep walls bounding inside corner bathymetry confirms that they mark the boundaries between segments on the flanks and that the deep sediment filled basins, typically identified as discordant zones, are attributable to outside corner bathymetry.
DE: 8100 TECTONOPHYSICS
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8150 Plate boundary--general (3040)
DE: 8158 Plate motions--present and recent (3040)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting