A great number of earthquakes occur within thick carbonate sequences in the shallow crust. At the same time, carbonate fault rocks exhumed from a depth < 6 km (i.e., from seismogenic depths) exhibit the coexistence of structures related to brittle (i.e., cataclasis) and ductile deformation processes (i.e., pressure-solution and granular plasticity). We performed friction experiments on water-saturated simulated carbonate-bearing faults for a wide range of normal stresses (from 5 to 120 MPa) and slip velocities (from 0.3 to 100 μm/s). At high normal stresses (σn > 20 MPa) fault gouges undergo strain-weakening, that is more pronounced at slow slip velocities, and causes a significant reduction of frictional strength, from μ = 0.7 to μ = 0.47. Microstructural analysis show that fault gouge weakening is driven by deformation accommodated by cataclasis and pressure- insensitive deformation processes (pressure solution and granular plasticity) that become more efficient at slow slip velocity. The reduction in frictional strength caused by strain weakening behaviour promoted by the acti- vation of pressure-insensitive deformation might play a significant role in carbonate-bearing faults mechanics.

Strength evolution of simulated carbonate-bearing faults. The role of normal stress and slip velocity / Mercuri, Marco; Scuderi, Marco Maria; Tesei, Telemaco; Carminati, Eugenio; Collettini, Cristiano. - In: JOURNAL OF STRUCTURAL GEOLOGY. - ISSN 0191-8141. - STAMPA. - 109:(2018), pp. 1-9. [10.1016/j.jsg.2017.12.017]

Strength evolution of simulated carbonate-bearing faults. The role of normal stress and slip velocity

Mercuri, Marco
;
Scuderi, Marco Maria;Carminati, Eugenio;Collettini, Cristiano
2018

Abstract

A great number of earthquakes occur within thick carbonate sequences in the shallow crust. At the same time, carbonate fault rocks exhumed from a depth < 6 km (i.e., from seismogenic depths) exhibit the coexistence of structures related to brittle (i.e., cataclasis) and ductile deformation processes (i.e., pressure-solution and granular plasticity). We performed friction experiments on water-saturated simulated carbonate-bearing faults for a wide range of normal stresses (from 5 to 120 MPa) and slip velocities (from 0.3 to 100 μm/s). At high normal stresses (σn > 20 MPa) fault gouges undergo strain-weakening, that is more pronounced at slow slip velocities, and causes a significant reduction of frictional strength, from μ = 0.7 to μ = 0.47. Microstructural analysis show that fault gouge weakening is driven by deformation accommodated by cataclasis and pressure- insensitive deformation processes (pressure solution and granular plasticity) that become more efficient at slow slip velocity. The reduction in frictional strength caused by strain weakening behaviour promoted by the acti- vation of pressure-insensitive deformation might play a significant role in carbonate-bearing faults mechanics.
2018
calcite; carbonate-bearing faults; friction; microstructures; geology
01 Pubblicazione su rivista::01a Articolo in rivista
Strength evolution of simulated carbonate-bearing faults. The role of normal stress and slip velocity / Mercuri, Marco; Scuderi, Marco Maria; Tesei, Telemaco; Carminati, Eugenio; Collettini, Cristiano. - In: JOURNAL OF STRUCTURAL GEOLOGY. - ISSN 0191-8141. - STAMPA. - 109:(2018), pp. 1-9. [10.1016/j.jsg.2017.12.017]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1104098
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