Frictional properties of exhumed fault gouges in DFDP‐1 cores, Alpine Fault, New Zealand. Issue 2 (27th January 2014)

• Record Type: Journal Article
• Authors: Boulton, Carolyn; Moore, Diane E.; Lockner, David A.; Toy, Virginia G.; Townend, John; Sutherland, Rupert
• Is Part Of: Geophysical research letters. Volume 41:Issue 2(2014:Jan.)
• Page Start: 356
• Page End: 362
• Publication Date: 2014-01-27
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2013GL058236
• Languages: English
• ISSNs: 0094-8276

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Principal slip zone gouges recovered during the Deep Fault Drilling Project (DFDP‐1), Alpine Fault, New Zealand, were deformed in triaxial friction experiments at temperatures, <italic>T</italic>, of up to 350°C, effective normal stresses, <italic>σ_n</italic>′, of up to 156 MPa, and velocities between 0.01 and 3 µm/s. Chlorite/white mica‐bearing DFDP‐1A blue gouge, 90.62 m sample depth, is frictionally strong (friction coefficient, <italic>μ</italic>, 0.61–0.76) across all experimental conditions tested (<italic>T</italic> = 70–350°C, <italic>σ_n</italic>′ = 31.2–156 MPa); it undergoes a transition from positive to negative rate dependence as <italic>T</italic> increases past 210°C. The friction coefficient of smectite‐bearing DFDP‐1B brown gouge, 128.42 m sample depth, increases from 0.49 to 0.74 with increasing temperature and pressure (<italic>T</italic> = 70–210°C, <italic>σ_n</italic>′ = 31.2–93.6 MPa); the positive to negative rate dependence transition occurs as <italic>T</italic> increases past 140°C. These measurements indicate that, in the absence of elevated pore fluid pressures, DFDP‐1 gouges are frictionally strong under conditions representative of the seismogenic crust.</p> </abstract>