Ripplocations provide a new mechanism for the deformation of phyllosilicates in the lithosphere

Aslin, Joe; Mariani, Elisabetta; Dawson, Karl; Barsoum, Michel W.

doi:10.1038/s41467-019-08587-2

Cited by 51 publications

(34 citation statements)

References 44 publications

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“…The presence of these discrete muscovite‐ and chlorite‐rich planes promoted connectivity between weak phyllosilicate grains that strongly localized deformation and weakened the rock (Bukovská et al, 2016; Ceccato et al, 2018; Hunter et al, 2016; Mariani et al, 2006; Menegon et al, 2008; Shea & Kronenberg, 1993; Wintsch et al, 1995). Finally, the presence of such phyllosilicate‐rich planes can accommodate large amount of strain, through the new mechanism of ripplocation motion (i.e., the motion of a new type of crystal defect—ripplocation—that involves a ripple of the basal layer and a basal dislocation, where the ripple enables c ‐axis parallel deformation in phyllosilicates; Kushima et al, 2015) rather than dislocation glide, as recently suggested by Aslin et al (2019).…”

Section: Discussionmentioning

confidence: 87%

Protracted Shearing at Midcrustal Conditions During Large‐Scale Thrusting in the Scandinavian Caledonides

et al. 2020

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During continental collision, large tracts of crust are mobilized along major shear zones. The metamorphic conditions at which these zones operate, the duration of thrusting, and the deformation processes that facilitated hundreds of km of tectonic transport are still unclear. In the Scandinavian Caledonides, the Lower Seve Nappe displays a main mylonitic foliation with thickness of~1 km. This foliation is overprinted by a brittle-to-ductile deformation pattern localized in C-and C′-type shear bands proximal to the tectonic contact with the underlying Särv Nappe. Thermobarometry of amphibolites and micaschists suggests a first high-pressure stage at 400-500°C and 1-1.3 GPa recorded in mineral relics. The main mylonitic foliation developed under epidote amphibolite facies conditions along the retrograde path from 600°C and 1 GPa to 500°C and 0.5 GPa. Age dating of synkinematic titanite grains in the amphibolites indicates that this mylonitic fabric formed at around 417 ± 9 Ma but older ages spanning 460-430 Ma could represent earlier stages of mylonitization. The shear bands developed at lower metamorphic conditions of 300-400°C and~0.3 GPa. In the micaschists, the recrystallized grain size of quartz decreases toward the shear bands. Monomineralic quartz layers are eventually dismembered to form polyphase aggregates deforming by dominant grain size sensitive creep accompanied by slip in muscovite and chlorite. Plagioclase zoning truncations suggest that the shear bands originated by fracturing followed by ductile deformation. The results suggest protracted and long-lasting shearing under amphibolite to greenschist facies conditions during the juxtaposition, stacking, and exhumation of the Lower Seve Nappe.

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Section: Discussionmentioning

confidence: 87%

Protracted Shearing at Midcrustal Conditions During Large‐Scale Thrusting in the Scandinavian Caledonides

et al. 2020

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“…5 c showing (marked by the red arrow) the vertical orientation of the graphitic lattice planes might be related to the formation of nanofolds (inset of Fig. 5 c) alongside the film due to an excess of uncompensated tangential stress 30 , 61 , 62 . Under high-resolution TEM, these nanofolds 30 revealed a crystalline orientation that differed from the rest of the NGF area; graphitic lattice basal planes were almost vertically oriented instead of horizontally, as in the rest of the thin film (inset of Fig.…”

Section: Resultsmentioning

confidence: 99%

Semi-transparent graphite films growth on Ni and their double-sided polymer-free transfer

Deokar

Genovese

Surya

et al. 2020

Sci Rep

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Nanorange thickness graphite films (NGFs) are robust nanomaterials that can be produced via catalytic chemical vapour deposition but questions remain regarding their facile transfer and how surface topography may affect their application in next-generation devices. Here, we report the growth of NGFs (with an area of 55 cm2 and thickness of ~ 100 nm) on both sides of a polycrystalline Ni foil and their polymer-free transfer (front- and back-side, in areas up to 6 cm2). Due to the catalyst foil topography, the two carbon films differed in physical properties and other characteristics such as surface roughness. We demonstrate that the coarser back-side NGF is well-suited for NO2 sensing, whereas the smoother and more electrically conductive front-side NGF (2000 S/cm, sheet resistance − 50 Ω/sq) could be a viable conducting channel or counter electrode in solar cells (as it transmits 62% of visible light). Overall, the growth and transfer processes described could help realizing NGFs as an alternative carbon material for those technological applications where graphene and micrometer-thick graphite films are not an option.

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“…Thouless et al, 1987). This mechanism bears an indirect resemblance to the recently proposed mechanism of phyllosilicate deformation via migration of so-called ripplocations where delamination of phyllosilicate layers occurs to release layer normal elastic strain (Aslin et al, 2019). We ignore the resistance offered by comminution or plastic bending of the cleaved-off basal slivers as the mechanical work needed to drive these processes is small (see Text S1 in the supporting information).…”

Section: Microstructural Modelmentioning

confidence: 92%

Low Friction Coefficient of Phyllosilicate Fault Gouges and the Effect of Humidity: Insights From a New Microphysical Model

2020

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Fault slip is often localized in phyllosilicate-rich fault gouges in a manner consistent with the relatively low friction coefficients measured for dry and especially wet phyllosilicates in laboratory experiments. However, the microphysics controlling these low friction coefficients remains unclear. Here, we propose a microphysical model, inspired by microstructural observations, for the prediction of the absolute value of the friction coefficient of pure dry and wet phyllosilicates. Experimentally produced phyllosilicate gouges suggest that shearing is controlled by sliding along (001) grain/platelet interfaces operating in series with removal of overlapping grain edge barriers by basal cleavage. We derive a model incorporating a subcritical crack propagation equation for the latter, constrained by subcritical crack growth data for muscovite. Model predictions for muscovite show similar trends regarding the effects of humidity and slip velocity on friction coefficient as do experiments at room temperature. The absolute value predicted for the friction coefficient is difficult to compare with experimental values, as it critically depends on atomic scale (001) sliding resistance, which is poorly constrained by available experimental data. Further discrepancies with experimental data can be explained by effects of varying grain size, grain aspect ratio, and porosity on the friction coefficient. While numerous qualitative explanations have been proposed previously for the low friction coefficient exhibited by phyllosilicates, especially in the presence of water, our study provides a new step toward a quantitative, physically based model.

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Ripplocations provide a new mechanism for the deformation of phyllosilicates in the lithosphere

Cited by 51 publications

References 44 publications

Protracted Shearing at Midcrustal Conditions During Large‐Scale Thrusting in the Scandinavian Caledonides

Protracted Shearing at Midcrustal Conditions During Large‐Scale Thrusting in the Scandinavian Caledonides

Semi-transparent graphite films growth on Ni and their double-sided polymer-free transfer

Low Friction Coefficient of Phyllosilicate Fault Gouges and the Effect of Humidity: Insights From a New Microphysical Model

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