New packer experiments and borehole logs in upper oceanic crust; evidence for ridge-parallel consistency in crustal hydrogeological properties

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doi: 10.1002/ggge.20201
Author(s): Becker, Keir; Fisher, Andrew T.; Tsuji, Takeshi
Author Affiliation(s): Primary:
University of Miami, Division of Marine Geology and Geophysics, Miami, FL, United States
University of California at Santa Cruz, United States
Kyushu University, Japan
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 14(8), p.2900-2915. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 69 refs.; illus., incl. 1 table
Summary: We report new drillstring packer permeability tests conducted during Integrated Ocean Drilling Program (IODP) Expedition 327 in upper oceanic basement in Hole U1362A on the eastern flank of the Juan de Fuca Ridge. Hole U1362A lies within a closely spaced array (40-2460 m separation) of six holes in well-sedimented 3.5-3.6 m.y. old crust that were drilled, tested, and instrumented with borehole observatories during Ocean Drilling Program Leg 168 and IODP Expeditions 301 and 327. The permeability tests in Hole U1362A complement similar experiments previously conducted in nearby Holes 1026B, 1027C, and U1301B. The new results suggest consistency of upper crustal permeability between Holes U1362A and U1301B, which penetrate 290 and 320 m of basement and are separated by ∼825 m. We obtain similar bulk permeability values of 1-3 × 10-12 m2 for the sections deeper than ∼150 m into basement in both holes. These values are significantly higher than results of packer experiments in the shallowest few tens of meters of basement in nearby Holes 1026B and 1027C, suggesting that the highest basement permeabilities in this area are not found in the shallowest basement layers. Downhole logs of density and penetration rate during drilling and coring in Holes U1362A and U1301B show similar trends within the upper crust, reinforcing the inference that there may be considerable lateral continuity in hydrogeologic properties. This continuity may be associated with the fundamental lithostratigraphy of the crust and/or influenced by ridge-parallel faulting and fracturing associated with the formation of abyssal hill topography. Abstract Copyright (2013), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; 20 Geophysics, Applied; Basement; Boreholes; Cores; Crust; Crystalline rocks; Downhole methods; East Pacific; Expedition 301; Expedition 327; Fracturing; Geophysical methods; Geophysical profiles; Geophysical surveys; Geothermal systems; Hydrogeology; IODP Site U1362; Instruments; Integrated Ocean Drilling Program; Juan de Fuca Ridge; Leg 168; North Pacific; Northeast Pacific; Ocean Drilling Program; Ocean floors; Oceanic crust; Pacific Ocean; Packer tests; Permeability; Physical properties; Porosity; Seismic methods; Seismic profiles; Surveys; Techniques; Upper crust; Well logs
Coordinates: N474530 N474540 W1274540 W1274543
Record ID: 2013095584
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