Frictional properties of basalt experimental faults and implications for volcano-tectonic settings and geo-energy sites
| Autor: | Marco M. Scuderi, Cristiano Collettini, Giulio Di Toro, Piercarlo Giacomel, Roberta Ruggieri, Elena Spagnuolo |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Shearing (physics)
Fault slip modes 010504 meteorology & atmospheric sciences Slip (materials science) Cataclastic rock 010502 geochemistry & geophysics 01 natural sciences Fault slip modes Frictional stability analysis Heterogeneous fault microstructure Strong faults Unaltered basalts earthquakes Geophysics Shear (geology) 13. Climate action Fault gouge Heterogeneous fault microstructure Shear velocity Shear zone Unaltered basalts Petrology Joint (geology) Frictional stability analysis Strong faults earthquakes Geology 0105 earth and related environmental sciences Earth-Surface Processes |
| Popis: | We performed a suite of experiments aimed at examining the frictional properties of unaltered basalts at conditions considered to be representative of slip at shallow depths in volcano-tectonic environments and in-situ geo-energy basaltic sites. Scientific drilling and field studies on exhumed subsurface faults and fractures analogues suggest that, frictional sliding in basalts can occur in shear zones within a volume of wear debris or along localized joint surfaces. To illuminate how microstructural heterogeneities affect the nucleation of slip instabilities in basalts, we sheared simulated fault gouge and bare rock surfaces at low normal stresses (4–30 MPa) at ambient temperature, under room-dry and wet conditions. We performed velocity steps (0.1–300 μm/s) and slide-hold-slides (30–3000 s holds) to determine the frictional stability and healing properties of basalts. In all the tests, we observed high friction coefficient associated with important frictional restrengthening. Overall, our results show that microstructural heterogeneities strongly affect the friction velocity dependence of basalts: while for normal stresses ≥10 MPa, shear localization accompanied by cataclasis and grain size reduction favors the transition to velocity weakening behavior of powdered samples, on bare surfaces gouge production during shearing promotes a transition to a velocity strengthening behavior. Our results imply that at the tested conditions, friction instabilities may promptly nucleate in shear zones where deformation within (unaltered) basaltic gouge layers is localized, such as those located along volcanic flanks, while joint surfaces characterized by rough rock-on-rock contacts are less prone to unstable slip, which is suppressed at velocities ≥10 μm/s. |
| Databáze: | OpenAIRE |
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