Dislocation creep of dry quartz

Kilian, Rüdiger; Heilbronner, Renée; Holyoke, C. W.; Kronenberg, A. K.; Stünitz, Holger

doi:10.1002/2015jb012771

Cited by 20 publications

(49 citation statements)

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“…The broad OH band and large water contents of the MT mylonites deformed at 300-350 • C are in line with previous FTIR studies of OH in quartz deformed under greenschist facies conditions Gleason and DeSisto, 2008). The sharp OH bands and low water contents of the MCT mylonites deformed at 535-735 • C are consistent with FTIR studies of quartz in other shear zones deformed at amphibolite conditions (Han et al, 2013;Kilian et al, 2016).…”

Section: Discussionsupporting

confidence: 89%

“…Our FTIR measurements of quartz OH contents using a 10 µm aperture show that these variations depend on sampling volume, as observed by Kilian et al (2016), who showed that broad OH band absorptions scale with size of the measurement area due to the inhomogeneous distributions of fluid inclusions.…”

Section: Wide Variations In Oh Contentsupporting

confidence: 83%

“…In small granitic shear zones deformed at greenschist conditions, water contents of quartz grains appear to correlate with finite strain Gleason and DeSisto, 2008), and in the much larger Median Tectonic Line of Japan, intragranular water contents increase towards its center (Nakashima et al, 1995). However, OH concentrations of quartz of granitic rocks deformed at higher temperatures can be much lower (20-100 ppm; Han et al, 2013;Kilian et al, 2016), with IR spectra dominated by small sharp OH bands of hydrogen point defects (Kilian et al, 2016) that are not thought to weaken quartz. Moreover, quartz water contents have been reported that show a trend of decreasing OH content towards the center of a high-grade Table 1.…”

Section: Introductionmentioning

confidence: 96%

“…With the introduction of efficient FTIR spectrometers and IR microscopes, studies of intragranular water and hydrogen defects in naturally deformed rocks have been enabled using apertures of 50-100 µm Nakashima et al, 1995;Gleason and DeSisto, 2008;Finch et al, 2016;Kilian et al, 2016) as well as FTIR mapping of OH contents (Seaman et al, 2013). Molecular water contents of naturally deformed quartz commonly have large grain-to-grain variations at this scale of observation, and it has not been possible to measure OH contents of fine, dynamically recrystallized grains without including OH bands associated with grain boundaries.…”

Section: Methodsmentioning

confidence: 99%

“…With the advent of FTIR and IR microscopes, water and hydrogen defects in naturally deformed quartz have been reported with OH contents of 300 to > 10 000 ppm (molar H/10 6 Si; Nakashima et al, 1995;Gleason and DeSisto, 2008;Seaman et al, 2013;Finch et al, 2016;Kilian et al, 2016), comparable to those required for water weakening in laboratory experiments. In small granitic shear zones deformed at greenschist conditions, water contents of quartz grains appear to correlate with finite strain Gleason and DeSisto, 2008), and in the much larger Median Tectonic Line of Japan, intragranular water contents increase towards its center (Nakashima et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

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Synchrotron FTIR imaging of OH in quartz mylonites

et al. 2017

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Abstract. Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR) instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.Synchrotron infrared (IR) radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR) plates can be prepared with thicknesses down to 4-8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples < 25 µm thick, precluding measurements of water within individual, finely recrystallized grains. By translating specimens under the 10 µm IR beam by steps of 10 to 50 µm, using a software-controlled x − y stage, spectra have been collected over specimen areas of nearly 4.5 mm 2 . This technique allowed us to separate and quantify broad OH bands due to fluid inclusions in quartz and OH bands due to micas and map their distributions in quartzites from the Moine Thrust (Scotland) and Main Central Thrust (Himalayas).Mylonitic quartzites deformed under greenschist facies conditions in the footwall to the Moine Thrust (MT) exhibit a large and variable 3400 cm −1 OH absorption band due to molecular water, and maps of water content corresponding to fluid inclusions show that inclusion densities correlate with deformation and recrystallization microstructures. Quartz grains of mylonitic orthogneisses and paragneisses deformed under amphibolite conditions in the hanging wall to the Main Central Thrust (MCT) exhibit smaller broad OH bands, and spectra are dominated by sharp bands at 3595 to 3379 cm −1 due to hydrogen point defects that appear to have uniform, equilibrium concentrations in the driest samples. The broad OH band at 3400 cm −1 in these rocks is much less common. The variable water concentrations of MT quartzites and lack of detectable water in highly sheared MCT mylonites challenge our understanding of quartz rheology. However, where water absorption bands can be detected and compared with deformation microstructures, OH concentration maps provide information on the histories of deformation and recovery, evidence for the introduction and loss of fluid inclusions, and water weakening processes.

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Section: Discussionsupporting

confidence: 89%

Section: Wide Variations In Oh Contentsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synchrotron FTIR imaging of OH in quartz mylonites

et al. 2017

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Water redistribution in experimentally deformed natural milky quartz single crystals—Implications for H₂O‐weakening processes

et al. 2017

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Natural quartz single crystals were experimentally deformed in two orientations: (1) ⊥ to one prism plane and (2) in O+ orientation at 900 and 1000°C, 1.0 and 1.5 GPa, and strain rates of ~1 × 10−6 s−1. In addition, hydrostatic and annealing experiments were performed. The starting material was milky quartz, which consisted of dry quartz with a large number of fluid inclusions of variable size up to several 100 µm. During pressurization fluid inclusions decrepitated producing much smaller fluid inclusions. Deformation on the sample scale is anisotropic due to dislocation glide on selected slip systems and inhomogeneous due to an inhomogeneous distribution of fluid inclusions. Dislocation glide is accompanied by minor dynamic recovery. Strongly deformed regions show a pointed broad absorption band in the ~3400 cm−1 region consisting of a superposition of bands of molecular H2O and three discrete absorption bands (at 3367, 3400, and 3434 cm−1). In addition, there is a discrete absorption band at 3585 cm−1, which only occurs in deformed regions and reduces or disappears after annealing, so that this band appears to be associated with dislocations. H2O weakening in inclusion‐bearing natural quartz crystals is assigned to the H2O‐assisted dislocation generation and multiplication. Processes in these crystals represent recycling of H2O between fluid inclusions, cracking and crack healing, incorporation of structurally bound H in dislocations, release of H2O from dislocations during recovery, and dislocation generation at very small fluid inclusions. The H2O weakening by this process is of disequilibrium nature because it depends on the amount of H2O available.

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Strength of dry and wet quartz in the low-temperature plasticity regime: insights from nanoindentation

Ceccato

Menegon

Hansen

2021

Preprint

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Experimental rock deformation has demonstrated that the strength of quartz is significantly reduced by the presence of intracrystalline H 2 O either bonded to the crystal lattice or occurring as micro-fluid inclusions, that is, quartz exhibits hydrolytic weakening (Ave Lallemant & Carter, 1971;Griggs, 1967;Griggs & Blacic, 1965;Tullis & Yund, 1980). Results from laboratory experiments established that hydrolytic weakening occurs in both synthetic and natural quartz crystals with intracrystalline H 2 O contents larger than 20-30 wt ppm (about 150 H/10 6 Si; Stünitz et al., 2017 and references therein). Several different microphysical processes have been proposed to explain hydrolytic weakening in quartz: (a) hydrolyzation of Si-O-Si bonds around dislocations, consequently decreasing the resistance to dislocation motion (i.e., reducing the Peierls stress; Griggs, 1967), (b) enhanced dislocation generation around H 2 O clusters within the crystal lattice (McLaren et al., 1989;Stünitz et al., 2017), and (c) enhanced recovery through increased ionic diffusivities and faster dislocation climb (Post et al., 1996;Tullis & Yund, 1989). Hydrolytic weakening has been experimentally observed in natural and synthetic quartz deformed at high homologous temperature, conditions for which dislocation climb and recovery processes control the overall strain rate (

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Dislocation creep of dry quartz

Cited by 20 publications

References 77 publications

Synchrotron FTIR imaging of OH in quartz mylonites

Synchrotron FTIR imaging of OH in quartz mylonites

Water redistribution in experimentally deformed natural milky quartz single crystals—Implications for H₂O‐weakening processes

Strength of dry and wet quartz in the low-temperature plasticity regime: insights from nanoindentation

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Dislocation creep of dry quartz

Cited by 20 publications

References 77 publications

Synchrotron FTIR imaging of OH in quartz mylonites

Synchrotron FTIR imaging of OH in quartz mylonites

Water redistribution in experimentally deformed natural milky quartz single crystals—Implications for H2O‐weakening processes

Strength of dry and wet quartz in the low-temperature plasticity regime: insights from nanoindentation

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Water redistribution in experimentally deformed natural milky quartz single crystals—Implications for H₂O‐weakening processes