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Frictional properties of exhumed fault gouges in DFDP‐1 cores, Alpine Fault, New Zealand
Author(s) -
Boulton Carolyn,
Moore Diane E.,
Lockner David A.,
Toy Virginia G.,
Townend John,
Sutherland Rupert
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl058236
Subject(s) - fault gouge , geology , chlorite , fault (geology) , slip (aerodynamics) , drilling , mineralogy , crust , mica , seismology , geochemistry , quartz , materials science , thermodynamics , metallurgy , paleontology , physics
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, T , of up to 350°C, effective normal stresses, σ n ′, 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, μ , 0.61–0.76) across all experimental conditions tested ( T = 70–350°C, σ n ′ = 31.2–156 MPa); it undergoes a transition from positive to negative rate dependence as T 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 ( T = 70–210°C, σ n ′ = 31.2–93.6 MPa); the positive to negative rate dependence transition occurs as T 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.