The permeability of young oceanic crust east of Juan de Fuca Ridge determined using borehole thermal measurements

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doi: 10.1029/97GL01286
Author(s): Fisher, A. T.; Becker, K.; Davis, E. E.
Author Affiliation(s): Primary:
University of California at Santa Cruz, Santa Cruz, CA, United States
University of Miami, United States
Geological Survey of Canada, Canada
Volume Title: Geophysical Research Letters
Source: Geophysical Research Letters, 24(11), p.1311-1314. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276 CODEN: GPRLAJ
Note: In English. 20 refs.; illus.
Summary: Temperature measurements made in Ocean Drilling Program (ODP) Hole 1026B, drilled into a sediment-buried basement ridge in 3.5 m.y. old crust on the eastern flank of Juan de Fuca Ridge, revealed fluid flow from the formation and into the overlying ocean. This flow indicates that the upper basaltic crust at this site is naturally overpressured relative to hydrostatic. This finding is consistent with output from previously published numerical models of hydrothermal circulation in the upper crust that include appropriate crustal geometry, sediment thickness, and basal heat flow. The fluid flowing into Hole 1026B enters the hole through the upper 10 m of basalt below the sediment-basement contact. The flow rate estimated from the thermal data (80-120 m/hr), in combination with the inferred basement overpressure relative to hydrostatic (about 20-30 kPa), was used to estimate the bulk permeability of the shallowest oceanic crust: 5 to 9 × 10-12 m2. Such high bulk permeability would allow regionally significant hydrothermal circulation, consistent with thermal homogenization of upper basement in this area. Copyright 1997 by the American Geophysical Union.
Year of Publication: 1997
Research Program: ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Basaltic composition; Boreholes; Crust; East Pacific; Fluid dynamics; Hydrothermal conditions; Instruments; Juan de Fuca Ridge; Leg 168; Measurement; North Pacific; Northeast Pacific; ODP Site 1026; Ocean Drilling Program; Oceanic crust; Overpressure; Pacific Ocean; Permeability; Physical properties; Tectonophysics; Thermal analysis
Coordinates: N474500 N480000 W1273000 W1290000
N474556 N474556 W1274526 W1274526
Record ID: 1999032411
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