Back to list of UTIG abstract submissions, Fall Agu 2003

G.L. Christeson and K.D. McIntosh (Univ. TX Institute for Geophysics, 4412 Spicewood Springs Rd, Bldg 600, Austin, TX, 78759; gail@ig.utexas.edu)

In July 2003 we conducted a seismic survey over fast-spreading crust adjacent to the Hess Deep rift. The program acquired 16 MCS profiles parallel to the scarp edge adjacent to the region where the lithologic boundary between the dikes and overlying extrusive section had been mapped by submersible dives. 2 of these profiles extended across the East Pacific Rise so that the shallow seismic structure could be continouously mapped from zero-age crust to the tectonic window where the shallow stratigraphy is exposed. The program also acquired 7 scarp-perpendicular MCS profiles, one of which extended across the Hess Deep rift onto the plateau adjacent to the south wall of the rift.

Initial processing indicates that the layer 2A reflector is imaged on all profiles; additional processing will allow us to map the layer 2A/2B boundary across a 15 km x 25 km region. For all profiles travel times of refractions were picked on every 10th shot gather (every 375 m) and were also used to map the layer 2A/2B boundary along each profile. Patterns in layer 2A thickness are very consistent between adjacent profiles which are located 0.5-2.0 km apart. In at least part of the study region there is a good correlation between depth to the layer 2A/2B boundary and the observed lithologic boundary between dikes and the overlying extrusives; additional analysis will be required to determine if this correlation exists over the entire survey area.