The rate of water penetration in experimentally deformed quartzite: implications for hydrolytic weakening

Post, Alice; Tullis, Jan

doi:10.1016/s0040-1951(98)00145-0

Cited by 74 publications

(66 citation statements)

References 34 publications

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“…Constant volume and homogeneous deformation were assumed. The reproducibility of strength measurements at our conditions is ±50 MPa [Hirth and Tullis, 1992;Post and Tullis, 1998]. …”

Section: Strength Determinationmentioning

confidence: 91%

“…Temperature and pressure were raised as follows along a path slightly modified from the work of Post and Tullis [1998]: to 100°C at 250 MPa, to 200°C at 400 MPa, to 300°C at 600 MPa and then to 900°C at 1500 MPa. This technique follows Kronenberg and Tullis [1984] and Post and Tullis [1998], whose mechanically sealed assemblies were effective in retaining added water. Most samples were preheated (at deformation P and T conditions) for 85 hours prior to deformation.…”

Section: Apparatus and Proceduresmentioning

confidence: 99%

“…Bars represent the range of strength from peak stress to stress at 40% strain. The strength of the vacuum-dried sample was normalized from a sample deformed at 800°C and 10 À6 s À1 by Post and Tullis [1998]. static sample.…”

Section: Unresolved Issuesmentioning

confidence: 99%

“…[2] Although it is well documented that trace amounts of water significantly decrease the strength of quartz deforming by dislocation creep [e.g., Griggs and Blacic, 1965;Tullis and Yund, 1989;Post and Tullis, 1998;Stipp et al, 2006], the effect of carbonic fluids has not been studied experimentally. Recent observations by Selverstone [2005] suggested that the presence of CO 2 -rich fluids resulted in the strengthening of schists in the eastern Alps.…”

Section: Introductionmentioning

confidence: 99%

“…Fast penetration of molecular water along cracks is followed by volume diffusion into the intercrack regions thus resulting in water weakening and, in our experiments, promoting chemical homogeneity throughout our samples. The results of Post and Tullis [1998], who deformed Heavitree quartzite (average grain size of $211 mm) with 0.3 wt.% water added after vacuum drying at 800°C, 1.5 GPa, and a strain rate of $1 Â 10 À5 s À1 , indicated that water had homogeneously entered quartz grains throughout the sample despite volume diffusion data for water in quartz that predicts a penetration distance of only $1 mm at 820°C (Doremus [1998] based on data from Kats [1962]). Their result suggests that microcracking may have contributed to rapid penetration of the added water into sample interiors.…”

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Effect of aqueous and carbonic fluids on the dislocation creep strength of quartz

et al. 2009

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[1] Dislocation creep experiments conducted on quartzite indicate that the presence of CO 2 can cause strengthening or weakening depending on the oxygen fugacity ( f O 2 ) of the deformation environment. Under oxidizing conditions (ferrosilite-hematite-quartz), the presence of CO 2 reduces the water fugacity ( f H 2 O ) and results in strengthening of the quartz. Under moderately reducing conditions ($Ni-NiO), CO 2 reacts with H 2 from the sample assembly to form graphite; the water produced by this reaction causes weakening. Under extremely reducing conditions (quartz-fayalite-iron), CO 2 is reduced to methane, a reaction that consumes original water, thereby increasing the strength of quartz. Our results show that increasing f H 2 O at constant confining pressure, by changing fluid composition, has a similar effect as increasing f H 2 O by increasing confining pressure. The f H 2 O exponent suggested by our data for the dislocation creep flow law is 0.375 to 1 (assuming a stress exponent of 3 to 4), which is on the low side of previously reported values. Differences in deformation behavior over small length scales may thus be related to local differences in the f O 2 that effectively change the f H 2 O in the presence of CO 2 .

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“…Constant volume and homogeneous deformation were assumed. The reproducibility of strength measurements at our conditions is ±50 MPa [Hirth and Tullis, 1992;Post and Tullis, 1998]. …”

Section: Strength Determinationmentioning

confidence: 91%

Section: Apparatus and Proceduresmentioning

confidence: 99%

Section: Unresolved Issuesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Effect of aqueous and carbonic fluids on the dislocation creep strength of quartz

et al. 2009

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Experimental constraints on the role of dynamic recrystallization on resetting the Ti‐in‐quartz thermobarometer

Nachlas

Hirth

2015

JGR Solid Earth

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We conducted deformation experiments on Ti‐doped quartz aggregates to investigate the effect of crystal‐plastic deformation and dynamic recrystallization on Ti substitution in quartz. Shear experiments were conducted at 1.0 GPa and 900°C at a constant shear strain rate (~5 × 10−6 s−1) for progressively longer intervals of time (24, 48, and 72 h). Equivalent experiments were conducted under hydrostatic stress to compare the effect of deformation relative to static crystallization. A novel quartz‐doping technique is used to synthesize a quartz aggregate consisting of two layers with Ti concentrations above and below the predicted solubility level for the experimental conditions. Samples deformed to progressively higher shear strain by dislocation creep accommodated by a combination of subgrain rotation and grain boundary migration recrystallization show a strengthening of the crystallographic preferred orientation that correlates with a progressive evolution of Ti concentrations. Quartz grains in the highest strain, most strongly recrystallized samples have Ti concentrations that are most similar to undeformed quartz grown in hydrostatic annealing experiments. Cathodoluminescence (CL) analysis of intragrain variations in Ti content reveals core and rim zoning present in the starting material that becomes progressively homogenized with increasing strain—recrystallized quartz in the highest‐strain samples exhibits a uniform CL signal. We conclude that dynamic recrystallization enhances the kinetics of trace element equilibration in quartz, illustrating that Ti‐in‐quartz thermobarometry is capable of recording the conditions of ductile shearing.

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Dislocation creep of dry quartz

et al. 2016

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Small‐scale shear zones within the Permian Truzzo meta‐granite developed during the Alpine orogeny at amphibolite facies conditions. In these shear zones magmatic quartz deformed by dislocation creep and recrystallized dynamically by grain boundary migration with minor subgrain rotation recrystallization to a grain size of around 250–750 µm, consistent with flow at low differential stresses. Fourier transform infrared (FTIR) spectroscopy reveals very low water contents in the interior of recrystallized grains (in the form of discrete OH peaks, ~20 H/106Si and very little broad band absorption, <100 H/106Si). The spectral characteristics are comparable to those of dry Brazil quartz. In FTIR spectra, magmatic quartz grains show a broad absorption band related with high water concentrations only in those areas where fluid inclusions are present while other areas are dry. Drainage of fluid inclusions and synkinematic growth of hydrous minerals indicates that a hydrous fluid has been available during deformation. Loss of intragranular water during grain boundary migration recrystallization did not result in a microstructure indicative of hardening. These FTIR measurements provide the first evidence that quartz with extremely low intragranular water contents can deform in nature by dislocation creep at low differential stresses. Low intragranular water contents in naturally deformed quartz may not be necessarily indicative of a high strength, and the results are contrary to implications taken from deformation experiments where very high water contents are required to allow dislocation creep in quartz. It is suggested that dislocation creep of quartz in the Truzzo meta‐granite is possible to occur at low differential stresses because sufficient amounts of intergranular water ensure a high recovery rate by grain boundary migration while the absence of significant amounts of intragranular water is not crucial at natural conditions.

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The rate of water penetration in experimentally deformed quartzite: implications for hydrolytic weakening

Cited by 74 publications

References 34 publications

Effect of aqueous and carbonic fluids on the dislocation creep strength of quartz

Effect of aqueous and carbonic fluids on the dislocation creep strength of quartz

Experimental constraints on the role of dynamic recrystallization on resetting the Ti‐in‐quartz thermobarometer

Dislocation creep of dry quartz

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