Quasi-equilibrium melting of quartzite upon extreme friction

Lee, Sung Keun; Han, Raehee; Kim, Eun Jeong; Jeong, Gi Young; Khim, Hoon; Hirose, Takehiro

doi:10.1038/ngeo2951

Cited by 37 publications

(35 citation statements)

References 30 publications

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“…Recent experimental work by Lee et al (2017) further confirmed that ultrafine quartz grains melt at temperature >200°C lower than that for bulk grains during seismic frictional sliding. Thus, we conclude that melting of ultra-fine grains in the gouge requires lower energy rate than melting the asperities of the bulk, host blocks, and melting occurs in the nanometric gouge.…”

Section: 1002/2017jb014462mentioning

confidence: 92%

Friction Evolution of Granitic Faults: Heating Controlled Transition From Powder Lubrication to Frictional Melt

2017

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The experimental shearing of granitic faults revealed complex evolution of strength and microstructure. We use a rotary shear apparatus to shear three types of granitic rocks at moderate slip velocity of 0.01–0.11 m/s, normal stress of 1.0–6.8 MPa, and slip distance up to 60 m. Three stages of strength evolution with slip distance were systematically observed. In Stage I, faults exhibited initial weakening in which the friction coefficient dropped to a steady state level of μ ≈ 0.3. This weakening is associated with powder lubrication and the development of cohesive gouge layers. Stage II included strengthening to μ ≈ 0.5 associated with volumetric expansion, melting of fault patches, and viscous braking at these patches. In Stage III, fault weakening is due to melt lubrication when the melted patches reach a critical fraction of the fault surface area. We show that this complex weakening‐strengthening‐weakening evolution is controlled by thermally activated deformation processes that can explain the friction behavior of igneous rocks at seismic velocity range.

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Section: 1002/2017jb014462mentioning

confidence: 92%

Friction Evolution of Granitic Faults: Heating Controlled Transition From Powder Lubrication to Frictional Melt

2017

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“…It might be assumed that temperatures due to friction must have locally exceeded the melting point of a-quartz (~1700°C; given limited eutectic melting due to the~90% SiO 2 content of the rock). However, Lee et al (2017) show that the preferential frictional melting of ultrafine particles and the metastable melting of bquartz can occur at temperatures as low as 1350-1500°C in quartzites. This stage terminates at the Hugoniot elastic limit as the shock front arrives (Fig.…”

Section: Shock Vein Modelmentioning

confidence: 97%

“…However, Lee et al. () show that the preferential frictional melting of ultrafine particles and the metastable melting of β‐quartz can occur at temperatures as low as 1350–1500 °C in quartzites. This stage terminates at the Hugoniot elastic limit as the shock front arrives (Fig.…”

Section: Shock Vein Modelmentioning

confidence: 99%

Quartz–coesite–stishovite relations in shocked metaquartzites from the Vredefort impact structure, South Africa

Spray

Boonsue

2017

Meteorit & Planetary Scien

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Abstract-Coesite and stishovite are developed in shock veins within metaquartzites beyond a radius of~30 km from the center of the 2.02 Ga Vredefort impact structure. This work focuses on deploying analytical field emission scanning electron microscopy, electron backscattered diffraction, and Raman spectrometry to better understand the temporal and spatial relations of these silica polymorphs. a-Quartz in the host metaquartzites, away from shock veins, exhibits planar features, Brazil twins, and decorated planar deformation features, indicating a primary (bulk) shock loading of >5 < 35 GPa. Within the shock veins, coesite forms anhedral grains, ranging in size from 0.5 to 4 lm, with an average of 1.25 lm. It occurs in clasts, where it displays a distinct jigsaw texture, indicative of partial reversion to a less dense SiO 2 phase, now represented by microcrystalline quartz. It is also developed in the matrix of the shock veins, where it is typically of smaller size (<1 lm). Stishovite occurs as euhedral acicular crystals, typically <0.5 lm wide and up to 15 lm in length, associated with clast-matrix or shock vein margin-matrix interfaces. In this context, the needles occur as radiating or subparallel clusters, which grow into/over both coesite and what is now microcrystalline quartz. Stishovite also occurs as more blebby, subhedral to anhedral grains in the vein matrix (typically <1 lm). We propose a model for the evolution of the veins (1) precursory frictional melting in a microfault (~1 mm wide) generates a molten matrix containing quartz clasts. This is followed by (2) arrival of the main shock front, which shocks to 35 GPa. This generates coesite in the clasts and in the matrix. (3) On initial shock release, the coesite partly reverts to a less dense SiO 2 phase, which is now represented by microcrystalline quartz. (4) With continued release, stishovite forms euhedral needle clusters at solid-liquid interfaces and as anhedral crystals in the matrix. (5) With decreasing pressure-temperature, the matrix completes crystallization to yield a microcrystalline quasi-igneous texture comprising quartz-coesite-stishovite-kyanite-biotitealkali feldspar and accessory phases. It is possible that the shock vein represents the locus of a thermal spike within the bulk shock, in which case there is no requirement for additional pressure (i.e., the bulk shock was ≃35 GPa). However, if that pressure was not realized from the main shock, then supplementary pressure excursions within the vein would have been required. These could have taken the form of localized reverberations from wave trapping, or implosion processes, including pore collapse, phase change-initiated volume reduction, and melt cavitation.

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“…The 0.5-2 mm-thick pseudotachylytes (i.e., solidified frictionally generated melts produced during seismic slip) were found from the faults in muscovite-bearing quartzite (Bestmann et al 2011). Recently, Lee et al (2017) conducted high-velocity (1.3 m/s) friction experiments on quartzite, which showed that quartz can melt at lower temperatures (1350-1500 °C) than expected (1730 °C). However, frictional behavior of silica-rich rocks at seismic slip rates and the underlying physical mechanisms remain poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Viscous strengthening followed by slip weakening during frictional melting of chert

Motohashi

Oohashi

Ujiie

2019

Earth Planets Space

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Pelagic chert is one of the major lithologies in accretionary complexes. Thus, frictional properties of chert at seismic slip rates are important for understanding of earthquake faulting in subduction zones. Here, we conducted highvelocity friction experiments on chert collected from the Jurassic accretionary complex in central Japan at a slip rate of 1.3 m/s and normal stresses of 5-13 MPa under room humidity conditions. The results show that initial slip weakening was followed by slip strengthening and subsequent second slip weakening toward a steady-state shear strength. Slip strengthening resulted from the formation of a silica-rich melt layer at lower melting temperatures than expected, which could be due to the presence of water in the illite-containing chert. The second slip weakening may be occurred due to a decrease in shear strain rate associated with the thickening of the melt layer. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Quasi-equilibrium melting of quartzite upon extreme friction

Cited by 37 publications

References 30 publications

Friction Evolution of Granitic Faults: Heating Controlled Transition From Powder Lubrication to Frictional Melt

Friction Evolution of Granitic Faults: Heating Controlled Transition From Powder Lubrication to Frictional Melt

Quartz–coesite–stishovite relations in shocked metaquartzites from the Vredefort impact structure, South Africa

Viscous strengthening followed by slip weakening during frictional melting of chert

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