HR: 1340h
AN: OS33A-1460    [Abstracts]
TI: Modeling Hydrothermal Processes at Slow Spreading Ridges
AU: * Lowell, R P
EM: bob.lowell@eas.gatech.edu
AF: Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA 30341 United States
AB: The correlation between magma supply and the site frequency, or plume incidence, of hydrothermal of hydrothermal systems becomes less robust at slower spreading ridges. This suggests other factors such as fault-controlled permeability and alternative heat sources (e.g., heat flux from the mantle and serpentinization) may play a larger role in determining vent site frequency along slow and ultra-slow spreading ridges. Here I consider various factors such as magma supply, deep faulting, serpentinization, and mantle heat flux in the context of a single pass model in order to estimate the likely importance of each. In most cases these factors are difficult to assess in detail because of insufficient information on the individual system parameters such as heat output, heat extraction area (or volume), etc. Despite the limitations, the results show that it is difficult to maintain long-lived hydrothermal system operating at both high heat output and high temperatures from mantle heat flux, deep faulting, or serpentinization alone Magmatic heat supply is likely, even at ultra-slow ridges. For the TAG and Rainbow systems on the Mid-Atlantic Ridge, available temperature and heat flow data can be used to constrain bulk permeability to be ~ 10¹³m², and 10¹² m², respectively. Conductive boundary layers are ~ 40 m and ~ 10 m, respectively. Given the longevity of recent activity at TAG, the system can realistically be driven by magmatic heat supply. Magmatic heat supply cannot realistically maintain the Rainbow field for its presumed long lifetime, however.
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 3035 Midocean ridge processes
DE: 8135 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8424)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005