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Distribution and height of methane bubble plumes on the Cascadia Margin characterized by acoustic imaging
Author(s) -
Heeschen Katja U.,
Tréhu Anne M.,
Collier Robert W.,
Suess Erwin,
Rehder Gregor
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl016974
Subject(s) - geology , seafloor spreading , methane , clathrate hydrate , bubble , plume , water column , ridge , accretionary wedge , panache , petrology , submarine pipeline , oceanography , geomorphology , mineralogy , hydrate , seismology , subduction , paleontology , mechanics , tectonics , meteorology , ecology , chemistry , physics , organic chemistry , biology
Submersible investigations of the Cascadia accretionary complex have identified localized venting of methane gas bubbles in association with gas hydrate occurrence. Acoustic profiles of these bubble plumes in the water column in the vicinity of Hydrate Ridge offshore Oregon provide new constraints on the spatial distribution of these gas vents and the fate of the gas in the water column. The gas vent sites remained active over the span of two years, but varied dramatically on time scales of a few hours. All plumes emanated from local topographic highs near the summit of ridge structures. The acoustic images of the bubble plumes in the water column disappear at water depths between 500 to 460 m, independent of the seafloor depth. This coincides with the predicted depth of the gas hydrate stability boundary of 510 to 490 m, suggesting that the presence of a hydrate skin on the bubble surface prevents them from rapid dissolution. The upper limit of the acoustic bubble plumes at 460 m suggests that dissolution of the residual bubbles is relatively rapid above the hydrate stability zone.