Influence of temperature on brittle creep in sandstones

International audienceThe characterization of time-dependent brittle creep, promoted by chemically active pore fluids, is fundamental to our understanding of the long-term evolution and dynamics of the Earth's crust. Here we report results from a study of the influence of temperature on both short-term strength and time-dependent brittle creep in three sandstones under triaxial stress conditions. We show that an increase in temperature from 20°to 75°C significantly enhances stress corrosion cracking in all three sandstones, leading to (1) a systematic reduction in strength during constant strain rate experiments and (2) an increase by several orders of magnitude in brittle creep strain rates during stress-stepping creep experiments. We also show that a conventional creep experiment performed at 75°C exhibits a qualitatively similar three-stage brittle creep curve as that observed at ambient temperature. Extrapolation of our results suggests that temperature is likely to be the dominant influence on the evolution of creep strain rate with depth in the shallow crust