Inderbitzen, K. E. et al. (2011): Seafloor uplift in middle valley, Juan de Fuca Ridge; new high-resolution pressure data

Leg/Site/Hole:
ODP 139
ODP 139 857
ODP 169 857
Identifier:
2012-039963
georefid

Creator:
Inderbitzen, K. E.
Rosenstiel School of Marine and Atmospheric Science, Department of Marine Geology & Geophysics, Miami, FL, United States
author

Becker, K.
Pacific Geoscience Centre, Canada
author

Davis, E. E.
author

Identification:
Seafloor uplift in middle valley, Juan de Fuca Ridge; new high-resolution pressure data
2011
In: Anonymous, AGU 2011 fall meeting
American Geophysical Union, Washington, DC, United States
2011
Currently, in-situ seafloor and basement pressures are continuously monitored and recorded by an ODP subseafloor hydrogeological observatory (CORK) located in Middle Valley, Juan de Fuca Ridge. Hole 857D was drilled in 1991 in thickly sedimented crust to a depth of 936 mbsf and instrumented with an original CORK that was replaced in 1996. A large hydrothermal field (Dead Dog) lies roughly 1.7 km north of the hole, and two isolated chimneys and several diffuse flow sites are located approximately 800 meters northeast. The borehole and the vent fields have been visited periodically by submersible/ROV since 1999. Recent results from the CORK at 857D have shown apparent seafloor uplift, supported by depth records from the submersible Alvin. A constant rate of pressure change of approximately 6 kPa/yr, from its initiation in 2005 to the visit in 2010, has reduced mean seafloor pressure by approximately 28 kPa, equivalent to nearly 3 meters of head. This uplift rate is several times the typical pre-eruption inflation rates observed at Axial Seamount further south along the Juan de Fuca Ridge. Initially, the apparent uplift at 857D did not seem to have any effect on local high-temperature hydrothermal venting, however recent operations in Middle Valley revealed distinct changes at not only the hydrothermal field to the northeast, but also a shutdown of high-temperature venting to the north of 857D. We will present new data from Middle Valley, including the first year of data collected by a high-resolution pressure data logger deployed at 857D in June, 2010.
English
Coverage:Geographic coordinates:
North:48.2631
West:-128.4248East: -128.4239
South:48.2628

Structural geology; Axial Seamount; basement; crust; East Pacific; high-resolution methods; hydrothermal vents; Juan de Fuca Ridge; Leg 139; lithosphere; mid-ocean ridges; North Pacific; Northeast Pacific; Ocean Drilling Program; oceanic crust; oceanic lithosphere; ODP Site 857; Pacific Ocean; pressure; seamounts; uplifts;

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