HR: 0800h
AN: OS41C-0496    [Abstracts]
TI: Methane Hydrates and Fluid Flow Along the Chilean Margin
AU: * Gardner, J M
EM: joan.gardner@nrl.navy.mil
AF: Naval Research Laboratory, Marine Geosciences Division, Marine Physics Branch, 4555 Overlook Avenue S.W., Washington, DC 23075
AU: Diaz-Naveas, J
EM: jdiaz@ucv.cl
AF: Pontificia Universidad Catolica de Valparaiso, Av. Altamirano, Valparaiso, 1480 Chile
AU: Pohlman, J W
EM: johnp@ccs.nrl.navy.mil
AF: Institute of Marine Science, College of William and Mary, Virginia, P.O. Box 1346, Gloucester Point, VA 23062
AU: Hagen, R A
EM: rhagen@qur.nrl.navy.mil
AF: Naval Research Laboratory, Marine Geosciences Division, Marine Physics Branch, 4555 Overlook Avenue S.W., Washington, DC 23075
AU: Coffin, R B
EM: rcoffin@ccs.nrl.navy.mil
AF: Naval Research Laboratory, Marine Biogeochemistry Section, 4555 Overlook Avenue S.W., Washington, DC 20375
AU: Wood, W T
EM: wwood@earthquake.nrlssc.navy.mil
AF: Naval Research Laboratory, Marine Geosciences Division, Seafloor Sciences Branch, 1005 Balch Boulevard, Stennis Space Center, MS 39529
AB: An international collaboration between the Naval Research Laboratory and Pontificia Universidad Catolica de Valparaiso (Chile) was developed to investigate methane hydrate distribution along sections of the Chilean margin. Preliminary data collected along the Chilean margin in 2003 by researchers from Chile and the Universities of Bremen and Kiel (GEOMAR) found a clear discrepancy between estimated heat flow inferred from the depth of the bottom simulating reflector (BSR) and direct measurement using a heatflow probe. The data indicated that fluid migration enhanced heat flow in the upper section of the sedimentary column. We conducted a more extensive and higher resolution survey in October 2004 to evaluate this discrepancy and determine if the phenomenon is a local or regional phenomenon. Multichannel seismic data collected in the region, suggest the BSR is shallower than expected. It is possible that tectonic movements present that shifted the BSR upward but did not immediately destabilize the hydrates. This investigation will address possible "in situ" destabilization kinematics. Complimentary pore water geochemical profiles from piston cores and thermal data collected with a heatflow probe instrument, will help reconcile the discrepancies observed between the seismic and heat flow observations. Preliminary sulfate profiles collected in April 2003 indicate downward fluid advection but no heatflow or thermal information was collected to support this observation. Data collected in October 2004 will provide a more thorough analysis of this relationship. Previous DTAGS data is coupled with the heat flow data to interpret the variation observed in the geochemical profiles Also, heatflow data collected during Fall 2003 and Spring 2004 will be compared to determine if seasonal variations in bottom water temperature affect near surface sediment heat flow.
DE: 4805 Biogeochemical cycles (1615)
DE: 4820 Gases
DE: 3015 Heat flow (benthic) and hydrothermal processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting