Frictional properties of feldspar-chlorite altered gouges and implications for fault reactivation in hydrothermal systems

As particularly common minerals in granites, the presence of feldspar and altered feldspar-chlorite gouges at hydrothermal conditions have important implications in fault strength and reactivation. We present laboratory observations of frictional strength and stability of feldspar (K-feldspar and albite) and altered feldspar-chlorite gouges under conditions representative of deep geothermal reservoirs to evaluate the impact on fault stability. Velocity-stepping experiments are performed at a confining stress of 95 MPa, pore pressures of 35–90 MPa and temperatures of 120–400°C representative of in situ conditions for such reservoirs. Our experiment results show that the feldspar gouge is frictionally strong (μ~0.71) at all experimental temperatures (~120–400℃) but transitions from velocity-strengthening to velocity-weakening at T>120°C. Increasing the pore pressure increases the friction coefficient (~0.70-0.87) and the gouge remains velocity weakening, but this weakening decreases as..., , , Zijuan Hu, Chongyuan Zhang, Lei Zhang, Derek Elsworth, Quan Gan, Huiru Lei, Manchao He, Leihua Yao. Frictional Properties of Feldspar-chlorite Altered Gouges and Implications for Fault Reactivation in Hydrothermal Systems. Journal of Geophysical Research: Solid Earth.

Data S1

The shear displacement and frictional coefficient data for all friction experiments on simulated feldspar and feldspar/chlorite mixed gouges.

Authors

Zijuan Hu
School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China
Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China

Chongyuan Zhang
Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing, 100081, China
School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, China

Lei Zhang
State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing, China

Derek Elsworth
Energy a...