Barbados Ridge hydrogeologic tests; implications for fluid migration along an active decollement

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doi: 10.1130/0091-7613(1997)025<0239:BRHTIF>2.3.CO;2
Author(s): Screaton, Elizabeth J.; Fisher, Andrew T.; Carson, Bobb; Becker, Keir
Author Affiliation(s): Primary:
University of Colorado, Department of Geological Sciences, Boulder, CO, United States
University of California at Santa Cruz, Santa Cruz, CA, United States
Lehigh University, Bethlehem, PA, United States
Rosenstiel School of Marine and Atmospheric Science, Miami, FL, United States
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 25(3), p.239-242. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. 27 refs.; illus., incl. 1 table, sketch map
Summary: Hydrogeologic tests were conducted at a sealed borehole penetrating the decollement of the Barbados Ridge accretionary complex. At low excess pore pressures [λ* = (Pp-Ph)/(Pl-Ph) = 0.0 to 0.36, where Pp = pore pressure, Ph = hydrostatic pressure, and Pl = lithostatic pressure], estimated permeabilities were comparable to those of similar, unfractured sediment. These tests complement shipboard packer tests completed at higher fluid pressures (λ* = 0.5 to 1.0) during Ocean Drilling Program (ODP) Leg 156. Together, the test results suggest a 4- to 5-order-of-magnitude permeability increase as fluid pressure varied from hydrostatic (λ* = 0) to lithostatic (λ* = 1). However, unlike the results of the shipboard packer tests, the test results presented here exhibit no evidence of a relationship between permeability and pore pressure. The combined findings from the two sets of hydrogeologic tests indicate that significant permeability increases can occur within the decollement at pore pressures below lithostatic pressure.
Year of Publication: 1997
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; Accretionary wedges; Atlantic Ocean; Barbados Ridge; Boreholes; Decollement; Experimental studies; Fluid dynamics; Fluid pressure; Hydrostatic pressure; Leg 156; Lithostatic pressure; Marine sediments; Mid-ocean ridges; North Atlantic; ODP Site 949; Ocean Drilling Program; Ocean floors; Permeability; Plate tectonics; Pore pressure; Pressure; Sediments; Subduction
Coordinates: N153000 N153000 W0580000 W0590000
Record ID: 1997030367
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States