Frictional properties and microstructural evolution of dry and wet calcite–dolomite gouges
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Published:2021-03-05
Issue:3
Volume:12
Page:595-612
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ISSN:1869-9529
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Container-title:Solid Earth
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language:en
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Short-container-title:Solid Earth
Author:
Demurtas MatteoORCID, Smith Steven A.F.ORCID, Spagnuolo ElenaORCID, Di Toro GiulioORCID
Abstract
Abstract. Calcite and dolomite are the two most common minerals in carbonate-bearing faults and shear zones. Motivated by observations of exhumed seismogenic faults in the Italian Central Apennines, we used a rotary-shear apparatus to investigate the frictional and microstructural evolution of ca. 3 mm thick gouge layers consisting of 50 wt % calcite and 50 wt % dolomite. The gouges were sheared at a range of slip rates (30 µm s−1–1 m s−1), displacements (0.05–0.4 m), and a normal load of 17.5 MPa under both room-humidity and water-dampened conditions. The frictional behaviour and microstructural evolution of the gouges were strongly influenced by the presence of water. At room humidity, slip strengthening was observed up to slip rates of 0.01 m s−1, which was associated with gouge dilation and the development of a 500–900 µm wide slip zone cut by Y-, R-, and R1-shear bands. Above a slip rate of 0.1 m s−1, dynamic weakening accompanied the development of a localised < 100 µm thick principal slip zone preserving microstructural evidence for calcite recrystallisation and dolomite decarbonation, while the bulk gouges developed a well-defined foliation consisting of organised domains of heavily fractured calcite and dolomite. In water-dampened conditions, evidence of gouge fluidisation within a fine-grained principal slip zone was observed at a range of slip rates from 30 µm s−1 to 0.1 m s−1, suggesting that caution is needed when relating fluidisation textures to seismic slip in natural fault zones. Dynamic weakening in water-dampened conditions was observed at 1 m s−1, where the principal slip zone was characterised by patches of recrystallised calcite. However, local fragmentation and reworking of recrystallised calcite suggests a cyclic process involving formation and destruction of a heterogeneous slip zone. Our microstructural data show that development of well-defined gouge foliation under the tested experimental conditions is limited to high velocities (>0.1 m s−1) and room humidity, supporting the notion that some foliated gouges and cataclasites may form during seismic slip in natural carbonate-bearing faults.
Funder
FP7 Ideas: European Research Council Marsden Fund
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Earth-Surface Processes,Geochemistry and Petrology,Geology,Geophysics,Soil Science
Reference92 articles.
1. Allen, J. R. L.: Principles of Physical Sedimentology, George Allen and Unwin, Boston, 272 pp., 1985. a 2. Aretusini S., Nuñez Cascajero, A., Spagnuolo, E., Tapetado, A., Vazquez, C., and Di Toro, G.: How hot is a lab-earthquake?, American Geophysical Union Fall Meeting, San Francisco, USA, 9–13 December 2019, 519812, M23E-0160, 2019. a, b 3. Austin, N. J. and Kennedy, L. A.: Textural controls on the brittle deformation of dolomite: Variations in peak strength, in: Deformation Mechanisms, Rheology and Tectonics: from Minerals to the Lithosphere, vol. 243, edited by: Gapais, D., Brun, J. P., and Cobbold, P. R., Geological Society, London, Special Publications, 37–49, 2005. a 4. Barber, D. J., Heard, H. C., and Wenk, H. R.: Deformation of dolomite single crystals from 20–800 ∘C, Phys. Chem. Miner., 7, 271–286, https://doi.org/10.1007/BF00311980, 1981. a 5. Beeler, N. M., Tullis, T. E., Blanpied, M. L., and Weeks, J. D.: Frictional behavior of large displacement experimental faults, J. Geophys. Res.-Sol. Ea., 101, 8697–8715, https://doi.org/10.1029/96JB00411, 1996. a
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