Riedel, Michael et al. (2010): Characterizing the thermal regime of cold vents at the northern Cascadia margin from bottom-simulating reflector distributions, heat-probe measurements and borehole temperature data
Leg/Site/Hole:
Related Expeditions:
IODP 311
Identifier:
ID:
2011-041918
Type:
georefid
ID:
10.1007/s11001-010-9080-2
Type:
doi
Creator:
Name:
Riedel, Michael
Affiliation:
Geological Survey of Canada, Natural Resources Canada, Sidney, BC, Canada
Role:
author
Name:
Trehu, A. M.
Affiliation:
Oregon State University, United States
Role:
author
Name:
Spence, G. D.
Affiliation:
University of Victoria, Canada
Role:
author
Identification:
Title:
Characterizing the thermal regime of cold vents at the northern Cascadia margin from bottom-simulating reflector distributions, heat-probe measurements and borehole temperature data
Year:
2010
Source:
In: Wang, Tan K. (editor), Cheng, Win-Ben (editor), Application of geophysical methods on gas-hydrate exploration
Publisher:
Springer, Dordrecht, Netherlands
Volume:
31
Issue:
1-2
Pages:
1-16
Abstract:
Several cold vents are observed at the northern Cascadia margin offshore Vancouver Island in a 10 km (super 2) region around Integrated Ocean Drilling Program Expedition 311 Site U1328. All vents are linked to fault systems that provide pathways for upward migrating fluids and at three vents methane plumes were detected acoustically in the water column. Downhole temperature measurements at Site U1328 revealed a geothermal gradient of 0.056 + or - 0.004 degrees C/m. With the measured in situ pore-water salinities the base of methane hydrate stability is predicted at 218-245 meters below seafloor. Heat-probe measurements conducted across Site U1328 and other nearby vents showed an average thermal gradient of 0.054 + or - 0.004 degrees C/m. Assuming that the bottom-simulating reflector (BSR) marks the base of the gas hydrate stability zone variations in BSR depths were used to investigate the linkages between the base of the gas hydrate stability zone and fluid migration. Variations in BSR depth can be attributed to lithology-related velocity changes or variations of in situ pore-fluid compositions. Prominent BSR depressions and reduced heat flow are seen below topographic highs, but only a portion of the heat flow reduction can be due to topography-linked cooling. More than half of the reduction may be due to thrust faulting or to pore-water freshening. Distinct changes in BSR depth below seafloor are observed at all cold vents studied and some portion of the observed decrease in the BSR depth was attributed to fault-related upwelling of warmer fluids. The observed decrease in BSR depth below seafloor underneath the vents ranges between 7 and 24 m (equivalent to temperature shifts of 0.07-0.15 degrees C). Copyright 2010 Springer Science+Business Media B.V.
Language:
English
Genre:
Serial
Rights:
URL:
Coverage: Geographic coordinates: North:48.4200 West:-126.5700 East:
-126.4700 South:48.3700
Keywords: Economic geology, geology of energy sources; Applied geophysics; bathymetry; bottom-simulating reflectors; British Columbia; bubbles; Bullseye Vent; Canada; Cascadia subduction zone; continental margin; downhole methods; East Pacific; Expedition 311; fluid dynamics; gas hydrates; geophysical methods; geophysical profiles; geophysical surveys; heat flow; Integrated Ocean Drilling Program; IODP Site U1328; lithofacies; measurement; North Pacific; Northeast Pacific; Pacific Ocean; petroleum; petroleum exploration; seismic methods; seismic profiles; surveys; temperature; thermal regime; Vancouver Island; vents; Western Canada;
.