DOI: 10.5061/dryad.4b8gthtkc
title: Frictional properties of feldspar-chlorite altered gouges and implications for fault reactivation in hydrothermal systems

description: 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&gt;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 pore
 pressures increase. The presence of alteration-sourced chlorite leads to a
 transition from velocity weakening to velocity strengthening in the mixed
 gouge at experimental temperatures and pore pressures. As a ubiquitous
 mineral in reservoir rocks, feldspar is shown to potentially contribute to
 unstable sliding over ranges in temperature and pressure typical in deep
 hydrothermal reservoirs. These findings emphasize that feldspar minerals
 may increase the potential for injection-induced seismicity on
 pre-existing faults if devoid of chlorite alteration.
description: 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 and Mineral Engineering, EMS Energy Institute and G3 Center,
 Pennsylvania State University, University Park, 16802, USA
 Quan Gan School of resources and safety
 engineering, Chongqing university, Chongqing 400044, China
 Huiru Lei State Key Laboratory of Earthquake
 Dynamics, Institute of Geology, China Earthquake Administration, Beijing,
 China Manchao He School of Mechanics and Civil
 Engineering, China University of Mining and Technology, Beijing 100083,
 China Leihua Yao School of Engineering and
 Technology, China University of Geosciences (Beijing), Beijing 100083,
 China ### File lists (files found within
 DataS1.zip) Hu_et_al_2023_CK-01.xlsx Hu_et_al_2023_CK-02.xlsx
 Hu_et_al_2023_CK-03.xlsx Hu_et_al_2023_CK-04.xlsx Hu_et_al_2023_CK-05.xlsx
 Hu_et_al_2023_CK-06.xlsx Hu_et_al_2023_CK-07.xlsx Hu_et_al_2023_CK-08.xlsx
 Hu_et_al_2023_CK-09.xlsx Hu_et_al_2023_CK-10.xlsx Hu_et_al_2023_CK-11.xlsx
 Hu_et_al_2023_CK-12.xlsx Hu_et_al_2023_CK-13.xlsx Hu_et_al_2023_CK-14.xlsx
 ### File description Hu_et_al_2023_CK-01.xlsx: C The shear displacement
 (column 1) and frictional coefficient (column 2) data for Experiment CK-01
 (confining pressure of 95MPa, pore pressure of 35MPa and temperature of
 180°C, mixed gouges). Hu_et_al_2023_CK-02.xlsx: C The shear displacement
 (column 1) and frictional coefficient (column 2) data for Experiment CK-02
 (confining pressure of 95MPa, pore pressure of 90MPa and temperature of
 180°C, mixed gouges). Hu_et_al_2023_CK-03.xlsx: C The shear displacement
 (column 1) and frictional coefficient (column 2) data for Experiment CK-03
 (confining pressure of 95MPa, pore pressure of 35MPa and temperature of
 400°C, mixed gouges). Hu_et_al_2023_CK-04.xlsx: C The shear displacement
 (column 1) and frictional coefficient (column 2) data for Experiment CK-04
 (confining pressure of 95MPa, pore pressure of 35MPa and temperature of
 300°C, mixed gouges). Hu_et_al_2023_CK-05.xlsx: C The shear displacement
 (column 1) and frictional coefficient (column 2) data for Experiment CK-05
 (confining pressure of 95MPa, pore pressure of 35MPa and temperature of
 400°C). Hu_et_al_2023_CK-06.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-06 (confining
 pressure of 95MPa, pore pressure of 35MPa and temperature of 300°C).
 Hu_et_al_2023_CK-07.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-07 (confining
 pressure of 95MPa, pore pressure of 35MPa and temperature of 180°C).
 Hu_et_al_2023_CK-08.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-08 (confining
 pressure of 95MPa, pore pressure of 35MPa and temperature of 120°C).
 Hu_et_al_2023_CK-09.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-09 (confining
 pressure of 95MPa, pore pressure of 35MPa and temperature of 120°C, mixed
 gouges). Hu_et_al_2023_CK-10.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-10 (confining
 pressure of 95MPa, pore pressure of 90MPa and temperature of 180°C).
 Hu_et_al_2023_CK-11.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-11 (confining
 pressure of 95MPa, pore pressure of 50MPa and temperature of 180°C, mixed
 gouges). Hu_et_al_2023_CK-12.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-12 (confining
 pressure of 95MPa, pore pressure of 50MPa and temperature of 180°C).
 Hu_et_al_2023_CK-13.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-13 (confining
 pressure of 95MPa, pore pressure of 70MPa and temperature of 180°C, mixed
 gouges). Hu_et_al_2023_CK-14.xlsx: C The shear displacement (column 1) and
 frictional coefficient (column 2) data for Experiment CK-14 (confining
 pressure of 95MPa, pore pressure of 70MPa and temperature of 180°C).