HR: 1340h
AN: T33B-1373    [Abstracts]
TI: Quantitative Analysis of a Hydrographic Transient Above Salty Dawg Hydrothermal Field, Juan de Fuca Ridge in Summer 2005
AU: * Kellogg, J P
EM: kellogj@u.washington.edu
AF: University of Washington Oceanography, Box 357940, Seattle, WA 98107, United States
AU: McDuff, R E
EM: mcduff@ocean.washington.edu
AF: University of Washington Oceanography, Box 357940, Seattle, WA 98107, United States
AB: During systematic repeat hydrography cruises to the Endeavour segment of the Juan de Fuca Ridge in the summers of 2004, 2005 and 2006, we encountered a transient increase in the water column heat content above the Salty Dawg hydrothermal field. First observed in July 2005 and mapped in greater detail in August 2005, this feature was not a typical event or megaplume as potential temperature anomalies were elevated from the plume top to the seafloor. An order of magnitude increase to the volume flux from Salty Dawg would be required to generate a neutrally buoyant plume of this size based on scaling analyses. The mode of geological forcing is unknown, making this observation unique in that no earthquakes have been detected in the time frame of this increased heat flux, though unanalyzed seismic data are available. The transient was sustained over a time period longer than is expected with a typical dike intrusion. Possible forcing mechanisms for this transient include: an increase of heat in an underlying magma chamber or advancement of a cracking front, a small scale dike intrusion or aseismic crustal movement. The transient disappeared before our return in August 2006, likely due to thermal expansion of shallow host rock decreasing the permeability. Results from simple models help constrain the contribution of each hypothesized mechanism.
DE: 0545 Modeling (4255)
DE: 3015 Heat flow (benthic)
DE: 4536 Hydrography and tracers
DE: 8130 Heat generation and transport
DE: 8135 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8424)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting