HR: 1340h
AN: T33A-0513    [Abstracts]
TI: Crustal Structure Along the Southeast Indian Ridge From Seismic Refraction Data
AU: * Holmes, R
EM: cholmes@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AU: Tolstoy, M
EM: tolstoy@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AU: Cochran, J R
EM: jrc@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AU: Floyd, J S
EM: jsfloyd@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AB: Segments of the Southeast Indian Ridge (SEIR) in the region between 100-116°E and 47-51°S exhibit a systematic eastward shift in morphology from a smooth axial high to a well-developed axial valley despite a nearly constant spreading rate (~72-76 mm/yr). With the concurrent lack of significant variation in mantle geochemistry, this section of the SEIR is ideal for investigating the interplay between melt supply, mantle temperature variations, and mid-ocean ridge morphology. Seismic refraction/wide-angle reflection data were collected along the SEIR as part of the R/V Maurice Ewing leg EW0114 from December 2001 and January 2002 using ocean bottom hydrophones (OBHs). Six ridge-parallel active-source lines both on-axis and approximately 20 km off-axis along four segments of the mid-ocean ridge system were designed to constrain long-wavelength variations in crustal thickness. Each seismic line consisted of four OBHs spaced to maximize segment coverage, with line lengths varying between 102 and 124 km. This study will present the 2-D crustal thickness models of the four ridge segments calculated from observed P-wave traveltimes using the tomo2D raytracing and tomographic inversion package [ Korenaga et al., 2000]. The use of inverse modeling will allow us to present quantitative constraints on model resolution and any observable trends in segment-to-segment crustal thickness variability.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3025 Marine seismics (0935, 7294)
DE: 3035 Midocean ridge processes
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
SC: Tectonophysics [T]
MN: Fall Meeting 2005