HR: 1330h
AN: B12A-0735    [PDF]
TI: High-Frequency Seismic Tomography of the EPR 9-50N Hydrothermal System
AU: * Reves-Sohn, R A
EM: rsohn@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Rd, MS 24, Woods Hole, MA 02540 United States
AU: Webb, S C
EM: scw@ldeo.columbia.edu
AF: Lamont Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AB: The sub-surface nature of fluid flow that fuels deep-sea hydrothermal systems is of fundamental importance to our understanding of how heat transfer from the Earth's interior at mid-ocean ridges supports unique biological communities, but it is difficult to constrain owing both to the complexity of the crustal accretion system and the difficulties associated with making relevant observations in the deep ocean. Here we present the results from a unique seismic tomography study of the shallow crust on the East Pacific Rise 9$\deg$50'N. We have imaged a high-velocity anomaly at the base of the extrusive layer on the rise axis, which may represent a mineral deposit formed as high-temperature fluids encounter cold pore fluids for the first time on their ascent to the seafloor. We use elastic models to relate the size of the seismic velocity anomaly to the size of the mineral deposit, and use first-order mass balance methods to constrain the feasibility of the mineral deposit interpretation with respect to accepted values for heat and mass flux at the 9$\deg$50'N vent fields. We consider our tomographic models in the context of high-resolution magnetic, gravity, and crack distribution surveys conducted at the site, and synthesize these results with convection/heat-transfer models to provide new constraints on the nature of sub-surface circulation at the EPR IS site.
DE: 1020 Composition of the crust
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3035 Midocean ridge processes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting