Scale dependence of in-situ permeability measurements in the Nankai accretionary prism; the role of fractures

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doi: 10.1029/2012GL051216
Author(s): Boutt, David F.; Saffer, Demian; Doan, Mai-Linh; Lin, Weiren; Ito, Takatoshi; Kano, Yasuyuki; Flemings, Peter; McNeill, Lisa C.; Byrne, Timothy; Hayman, Nicholas W.; Moe, Kyaw Thu
Author Affiliation(s): Primary:
University of Massachusetts-Amherst, Department of Geosciences, Amherst, MA, United States
Pennsylvania State University, United States
Université Joseph Fourier, France
Japan Agency for Marine-Earth Science and Technology, Japan
Tohoku University, Japan
Kyoto University, Japan
University of Texas at Austin, United States
University of Southampton, United Kingdom
University of Connecticut, United States
Volume Title: Geophysical Research Letters
Source: Geophysical Research Letters, 39(7). Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276 CODEN: GPRLAJ
Note: In English. 40 refs.; illus., incl. geol. sketch map
Summary: Modeling studies suggest that fluid permeability is an important control on the maintenance and distribution of pore fluid pressures at subduction zones generated through tectonic loading. Yet, to date, few data are available to constrain permeability of these materials, at appropriate scales. During IODP Expedition 319, downhole measurements of permeability within the uppermost accretionary wedge offshore SW Japan were made using a dual-packer device to isolate 1 m sections of borehole at a depth of 1500 m below sea floor. Analyses of pressure transients using numerical models suggest a range of in-situ fluid permeabilities (5E-15-9E-17 m2). These values are significantly higher than those measured on core samples (2E-19 m2). Borehole imagery and cores suggests the presence of multiple open fractures at this depth of measurement. These observations suggest that open permeable natural fractures at modest fracture densities could be important contributors to overall prism permeability structure at these scales.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Accretionary wedges; Crust; Expedition 319; Fractures; IODP Site C0009; In situ; Integrated Ocean Drilling Program; Lithosphere; Models; Nankai Trough; North Pacific; Northwest Pacific; Oceanic crust; Oceanic lithosphere; Pacific Ocean; Permeability; Plate tectonics; Subduction; Subduction zones; West Pacific
Coordinates: N330000 N350000 E1380000 E1360000
Record ID: 2013017740
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