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

Mercuri, Marco; Scuderi, M. M.; Tesei, Telemaco; Carminati, Eugenio; Collettini, Cristiano

doi:10.1016/j.jsg.2017.12.017

Cited by 11 publications

(11 citation statements)

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“…The mechanical abrasion produces a calcite‐rich nanopowder that is spread on the Y‐shears. The activation of pressure‐solution processes dissolving the finer calcite grains may result in the formation of an ultra‐polished surface (e.g., Mercuri et al., 2018 ; Tesei et al., 2017 ). Alternatively, ultra‐polished slip surfaces produced by extreme co‐seismic localization at larger crustal depths (De Paola et al., 2015 ; Demurtas et al., 2016 ; Fondriest et al., 2013 ; Pozzi et al., 2018 ) might be overprinted by low‐temperature pressure‐solution compaction during inter‐seismic periods and exhumation.…”

Section: Discussionmentioning

confidence: 99%

Active Faulting and Deep‐Seated Gravitational Slope Deformation in Carbonate Rocks (Central Apennines, Italy): A New “Close‐Up” View

et al. 2021

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Section: Discussionmentioning

confidence: 99%

Active Faulting and Deep‐Seated Gravitational Slope Deformation in Carbonate Rocks (Central Apennines, Italy): A New “Close‐Up” View

et al. 2021

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“…The mechanical abrasion produces a calcite-rich nanopowder that is spread on the Y-shears. The activation of pressure-solution processes dissolving the finer calcite grains may result in the formation of an ultra-polished surface (e.g., Mercuri et al, 2018;Tesei et al, 2017). Alternatively, ultra-polished slip surfaces produced by extreme co-seismic localization at larger crustal depths (De Paola et al, 2015;Demurtas et al, 2016;Fondriest et al, 2013;Pozzi et al, 2018) might be overprinted by low-temperature pressure-solution compaction during inter-seismic periods and exhumation.…”

Section: Matrix Of the Slip Zonesmentioning

confidence: 99%

Active faulting and deep-seated gravitational slope deformation in carbonate rocks (central Apennines, Italy): a new "close-up" view

Rio

Moro

Fondriest

et al. 2021

Preprint

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Active faulting and deep-seated gravitational slope deformation (DGSD) are common geological hazards in mountain belts worldwide. In the Italian central Apennines, kilometer-thick carbonate sedimentary sequences are cut by major active normal faults that shape the landscape, generating intermontane basins. Geomorphological observations suggest that the DGSDs are commonly located in fault footwalls. We selected five mountain slopes affected by DGSD and exposing the footwall of active seismogenic normal faults exhumed from 2 to 0.5 km depth. Field structural analysis of the slopes shows that DGSDs exploit preexisting surfaces formed both at depth and near the ground surface by tectonic faulting and, locally, by gravitational collapse. Furthermore, the exposure of sharp scarps along mountain slopes in the central Apennines can be enhanced either by surface seismic rupturing or gravitational movements (e.g., DGSD) or by a combination of the two. At the microscale, DGSDs accommodate deformation mechanisms similar to those associated with tectonic faulting. The widespread compaction of micro-grains (e.g., clast indentation), observed in the matrix of both normal faults and DGSD slip zones, is consistent with clast fragmentation, fluid-infiltration, and congruent pressuresolution active at low ambient temperatures (<60°C) and lithostatic pressures (<80 MPa). Although clast comminution is more intense in the slip zones of normal faults because of the larger displacement accommodated, we are not able to find microstructural markers that allow us to uniquely distinguish faults from DGSDs.DEL RIO ET AL.

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“…They reported grain sizes down to~10-50 nm in all samples investigated, and the presence of amorphized materials, except in the carbonates. However, there are numerous (recent) reports of nanocrystalline PSZs formed in Minerals 2019, 9, 328 7 of 25 LVF and HVF experiments using simulated fault samples composed of carbonates [58,93,[112][113][114][115][116][117][118][119], many of which also showed the presence of amorphous materials ( Table 2).…”

Section: Nanocrystalline Principal Slip Zones Formed In Fault-slip Exmentioning

confidence: 99%

Nanocrystalline Principal Slip Zones and Their Role in Controlling Crustal Fault Rheology

2019

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Principal slip zones (PSZs) are narrow (<10 cm) bands of localized shear deformation that occur in the cores of upper-crustal fault zones where they accommodate the bulk of fault displacement. Natural and experimentally-formed PSZs consistently show the presence of nanocrystallites in the <100 nm size range. Despite the presumed importance of such nanocrystalline (NC) fault rock in controlling fault mechanical behavior, their prevalence and potential role in controlling natural earthquake cycles remains insufficiently investigated. In this contribution, we summarize the physical properties of NC materials that may have a profound effect on fault rheology, and we review the structural characteristics of NC PSZs observed in natural faults and in experiments. Numerous literature reports show that such zones form in a wide range of faulted rock types, under a wide range of conditions pertaining to seismic and a-seismic upper-crustal fault slip, and frequently show an internal crystallographic preferred orientation (CPO) and partial amorphization, as well as forming glossy or "mirror-like" slip surfaces. Given the widespread occurrence of NC PSZs in upper-crustal faults, we suggest that they are of general significance. Specifically, the generally high rates of (diffusion) creep in NC fault rock may play a key role in controlling the depth limits to the seismogenic zone.In this paper, we aim to elucidate the significance of nanocrystalline PSZs in Earth's upper crust. We start with background on fault mechanics and upper-crustal seismogenesis, and summarize some key physical properties of nanophase materials which, when applied to fault rock, are expected to be of major importance in controlling fault strength and stability. We go on to review the micro-and nanostructural characteristics of natural and experimentally-formed nanocrystalline PSZs, and list reports from the literature of PSZs characterized by grains <100 nm in size. Our work demonstrates that nanocrystalline PSZs form under a wide range of conditions pertaining slow (a-seismic) and fast (co-seismic) upper-crustal fault slip. Also, we observe that they are frequently characterized by an internal crystallographic preferred orientation, and by the presence of amorphous materials and/or glossy fault plane interfaces known as "mirror-slip" surfaces. Given the abundant observations of nanocrystalline PSZs in field exposures of faults, as well as in experiments, we suggest that they are of general importance to upper-crustal fault deformation. The physical properties of nanocrystalline fault rock may play a key role in natural earthquake cycles, especially in controlling the depth distribution of upper-crustal seismicity. Fault Zones, Earthquakes, and the Seismogenic ZoneThe presence of long-lived, localized zones of shear deformation in the crust, or fault zones, implies that the fault rocks within are weaker than the surrounding country rocks and that their weakness is persistent [14,15]. The strength of the upper-crust is classically approximated using a Cou...

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

Cited by 11 publications

References 43 publications

Active Faulting and Deep‐Seated Gravitational Slope Deformation in Carbonate Rocks (Central Apennines, Italy): A New “Close‐Up” View

Active Faulting and Deep‐Seated Gravitational Slope Deformation in Carbonate Rocks (Central Apennines, Italy): A New “Close‐Up” View

Active faulting and deep-seated gravitational slope deformation in carbonate rocks (central Apennines, Italy): a new "close-up" view

Nanocrystalline Principal Slip Zones and Their Role in Controlling Crustal Fault Rheology

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