HR: 14:40h
AN: T43D-05    [Abstracts]
TI: Transform Faults, Gravity Lineaments, and Seamounts
AU: * Sandwell, D T
EM: dsandwell@ucsd.edu
AF: Scripps Inst. of Oceanography, University of California San Diego 9500 Gilman Drive, La Jolla, CA 92093-0225 United States
AU: Smith, W H
EM: walter@raptor.grdl.noaa.gov
AF: NOAA Laboratory for Satellite Altimetry, 1335 East-West Highway, Silver Spring, MD 20910-3282 United States
AB: Age offsets along transform faults control the thermal structure and integrated strength of oceanic lithosphere. Preliminary analyses of marine gravity data from satellite altimetry suggests that seamount population density is systematically higher in younger lithospheric corridors than it is in order lithospheric corridors [Craig and Sandwell, Global Distribution of Seamounts from Seasat Profiles, J. Geophys. Res., 93, 10408-10420, 1988]. Moreover, the 150-km wavelength gravity lineaments in the central Pacific are most intense in corridors of younger lithosphere and volcanic ridges are preferentially located in troughs of gravity lineatments. These preliminary observations suggest that lithospheric thermal structure and strength have a primary control on seamount abundance. We developed a new global marine gravity anomaly model, with errors 30% lower than our previous global models, to map small seamounts and volcanic ridges in relation to the major Pacific fracture zones. The improvement in gravity precision is achieved by re-tracking the raw echoes of the Geosat and ERS-1 radar altimeters using an algorithm that is optimized for recovery of along-track sea surface slope by assuming the significant wave height varies smoothly along track [Smith and Sandwell, this meeting]. Repeat ERS-1 cycles across the South Pacific (area of high sea state) show improvement in along-track slope error from 6.45 microradian to 4.01 microradian and there is a corresponding improvement in resolution from 40 km to 33 km. We will also use the improved gravity resolution to identify plate reorganizations that are sometimes associated with higher seamount abundance.
UR: http://topex.ucsd.edu
DE: 8158 Plate motions--present and recent (3040)
DE: 3045 Seafloor morphology and bottom photography
DE: 1219 Local gravity anomalies and crustal structure
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting