Measurements of transience and downward fluid flow near episodic methane gas vents, Hydrate Ridge, Cascadia

Aqueous flux measurements within cold seep regions on northern Hydrate Ridge, Cascadia, indicate a high degree of variability, with extended periods of downflow and reversals of flow direction over periods of weeks to months. Local episodic venting of free methane gas was also observed. The instrume...

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Bibliographic Details
Published in:Geology (Boulder) 1999-12, Vol.27 (12), p.1075-1078
Main Authors: Tryon, Michael D, Brown, Kevin M, Torres, Marta E, Trehu, Anne M, McManus, James, Collier, Robert W
Format: Article
Language:English
Subjects:
accretionary wedges
aliphatic hydrocarbons
alkanes
Cascadia subduction zone
Changes
cold seeps
discharge
East Pacific
gas hydrates
gas vents
gases
Geology
Hydrate Ridge
hydrocarbons
Lava
Methane
mid-ocean ridges
North Pacific
Northeast Pacific
ocean floors
Oceanography
Oceans
Oregon
organic compounds
Pacific Ocean
periodicity
sea water
Studies
transient phenomena
United States
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Summary:Aqueous flux measurements within cold seep regions on northern Hydrate Ridge, Cascadia, indicate a high degree of variability, with extended periods of downflow and reversals of flow direction over periods of weeks to months. Local episodic venting of free methane gas was also observed. The instruments recorded similar changes in hydrologic flow patterns both on and off clam fields, the magnitude of the flow rates decreasing away from the clam field. The coincidence of episodic gas venting with nearby highly variable aqueous fluid flow suggests that they may be coupled. We propose that these observations are consistent with the action of a gas-driven pump that operates somewhat like a geyser. The hypothesis of gas-driven pumping of seawater through northern Hydrate Ridge has important ramifications for the mass fluxes through this region.
ISSN:0091-7613
1943-2682
DOI:10.1130/0091-7613(1999)027<1075:MOTADF>2.3.CO;2