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quartz dislocation creep

[Talk] In: GeoFrankfurt 2014. , 21.-24.09.2014, Frankfurt am Main . Quartz mainly occurs as an interstitial phase with weak LPO patterns interpreted as random. Wet polycrystalline quartz aggregates deformed at temperatures T of 600°-900°C and strain rates of 10-4-10-6 s-1 at a confining pressure Pc of 1.5 GPa exhibit plasticity at low T, governed by dislocation glide and limited recovery, and grain size-sensitive creep at high T, governed by diffusion and sliding at grain boundaries. Under experimental pressure and temperature conditions, the flow stress of pipe-diffusion-controlled dislocation creep … Theoretical derivation of flow laws for quartz dislocation creep: Comparisons with experimental creep data and extrapolation to natural conditions using water fugacity corrections . Stipp, Michael (2014) Dislocation creep of quartz - An updated correlation between natural and experimental deformation. Rutile deformation mechanisms probably involve dislocation creep as well as diffusion creep. However, at present, laboratory methods are not sufficient to accurately constrain the rheology of rocks deforming in the subsurface at geologic strain Small scale shear zones formed during heterogeneous, amphibolite facies condition in the Truzzo granite in the Penninic Tambo nappe. By Jun-ichi Fukuda and Ichiko Shimizu. The theory also predicts significant effects for the transition of α-β quartz under crustal conditions. Dry quartz is extremely strong and does not deform by dislocation creep in deformation experiments at the low differential stress levels that would correspond to natural deformation. Quartz grains are elongated approximately 2:1, oblique to the mica foliation, consistent with dextral (top to the right) sense of shear. Detail of 21. This is a deformed gneiss from the Piedmont of Georgia. dislocation creep models of β-quartz involving the water fugacity term. Quartz grain size reduction in a granitoid rock and the transition from dislocation to diffusion creep Rüdiger Kiliana,*, Renée Heilbronnera, Holger Stünitzb aGeological Institute, Department of Environmental Sciences, Basel University, Bernoullistrasse 32, CH-4056 Basel, Switzerland b Department of Geology, University of Tromsø, Dramsveien 201, 9037 Tromsø, Norway 4)Dislocation Creep Regimes in Quartz Aggregates. Quartz mainly occurs as an interstitial phase with weak LPO patterns interpreted as random. 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. In naturally deformed rocks, however, there are indications that carbonic fluids act to strengthen quartz-rich rocks. Deformation involving a combination of diffusion with dislocation glide are known as dislocation creep. Rather, they have transformed initially to short monocrystalline ribbons and ultimately to long polycrystalline ribbons. Abstract Using optical and TEM microscopy we have determined that three regimes of dislocation creep occur in experimentally deformed quartz aggregates, depending on the relative rates of grain boundary migration, dislocation climb and dislocation production. (B) The piezometer and geothermometer estimates define a strength-temperature curve for hydrous oceanic crust, which is far weaker than dry diabase . Jun‐ichi Fukuda, Ichiko Shimizu, Theoretical derivation of flow laws for quartz dislocation creep: Comparisons with experimental creep data and extrapolation to natural conditions using water fugacity corrections, Journal of Geophysical Research: Solid Earth, 10.1002/2016JB013798, 122, 8, … Magmatic quartz grains recrystallized dynamically by subgrain rotation and grain boundary migration. ties ofits mainconstituentminerals. In contrast to feldspar, quartz grains have not recrystallized into smaller grains at any stage of deformation. Quartz aggregates disintegrate because quartz fails to deform by dislocation creep compliant with the matrix.\ud \ud In the Gran Paradiso shear zones (lower amphibolite facies, ~500-550°C), a stable quartz grain size forms by a dynamic equilibrium. Dislocation creep of quartz has been extensively studied in laboratories, but the flow law parameters determined for different starting materials and deformation conditions using solid or gas medium apparatus have large uncertainties. 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. Creep in many crystalline materials has beenshownto change, as the applied stress, cr, decreases, frompowerlaw dislocation creep with a stress exponent, n, of3 to 5 to Newtonianviscous flow withn = 1. Quartz is one of them. Small-scale shear zones within the Permian Truzzo meta-granite developed during the Alpine orogeny at amphibolite facies conditions. on dislocation creep of quartz or feldspar [3–11].For the upper mantle, an olivine-controlled rheology is commonly assumed [12]. The absence of crystal‐plastic deformation of clastic quartz suggests that the flow stress in the host metagreywacke remained below a few tens of MPa at temperatures of 250–300 °C. In contrast, the microfabric of the folded quartz veins indicates deformation by dislocation creep accompanied by subgrain rotation recrystallization. Full text not available from this repository. Quartz has not deformed solely by dislocation creep but also by a diffusion-controlled mechanism. Trace amounts of water have long been known to significantly reduce the strength of quartz deforming by dislocation creep, but the effect of carbonic fluids has not been documented experimentally. The presence of a monoclinic shape fabric and a crystallographic preferred orientation are typical for deformation by dislocation creep. Using optical and TEM microscopy we have determined that three regimes of dislocation creep occur in experimentally deformed quartz aggregates, depending on the relative rates of grain boundary migration, dislocation climb and dislocation production. Previous research has outlined several dislocation creep regimes present in experimental conditions. However, at slower strain rates and/or higher temperatures, there are other processes involving diffusion that can assist with dislocation motion. A. K. Kronenberg's 102 research works with 4,621 citations and 6,203 reads, including: Deformation of Fine-Grained Quartz Aggregates by Mixed Diffusion and Dislocation Creep This is undulose extinction as manifest in quartz, and is due to lattice misorientation from accumulated line dislocations, and is good evidence of the operation of dislocation glide. Jun‐ichi Fukuda and Ichiko Shimizu, Theoretical derivation of flow laws for quartz dislocation creep: Comparisons with experimental creep data and extrapolation to natural conditions using water fugacity corrections, Journal of Geophysical Research: Solid Earth, 122, 8, (5956-5971), (2017). Deformation involving a combination of diffusion with dislocation glide are known as dislocation creep. This is because diffusion coefficients for α‐quartz, which control dislocation creep, are lower in natural conditions, facilitating dislocation creep but higher in experimental conditions. The theory also predicts significant effects for the transition of α-β quartz under crustal conditions. The LPO of rutile duplicate the LPO of omphacite and a similar distinction between S- and L-type was used. The LPO of rutile duplicate the LPO of omphacite and a similar distinction between S- and L-type was used. The Newtonian behavior could be induced by diffusional creep involving the The metacarbonates show a centimeter-scale alternation of coarse-grained domains of calcite and quartz, and fine-grained domains of a mix of phases (calcite, dolomite, phyllosilicates, quartz, and apatite). The experimentally determined shear strength of quartz undergoing dislocation creep gives stresses close to the estimated values for the exhumed shear zones at a strain rate of 10 −12 s −1. From the microstructural observations and CPO data, we interpret that both minerals primarily deform via dislocation creep at amphibolite-grade deformation temperatures (about 500-600˚C), but quartz deforms more easily by dislocation creep due to enhanced dislocation climb relative to plagioclase. Mechanisms of recrystallization. Deformed quartz crossed polars. Rutile deformation mechanisms probably involve dislocation creep as well as diffusion creep. Deformed quartz crossed polars; Dislocation creep. This could cause serious errors in extrapolation of the flow laws to The stress-strain rate relation reported by Rutter and Brodie (2004b) for fine-grained quartz aggregates is nearly Newtonian, with a stress exponent of 1.0. Dislocation climb is important in the dislocation creep of quartz. Under experimental pressure and temperature conditions, the flow stress of pipe-diffusion-controlled dislocation creep is higher than that for volume-diffusion-controlled creep. Two main mechanisms for altering grain boundaries have been defined. Dislocation creep. In mica-poor layers, quartz recrystallized grain size is larger: Recrystallized grain size is limited by mica grains pinning the grain boundaries; dislocation creep … However, at slower strain rates and/or higher temperatures, there are other processes involving diffusion that can assist with dislocation motion. 1) Dislocation climb difficult, low grain boundary mobilities, high dislocation density contrasts; leads to dislocation glide accommodated by … Dislocation climb is important in the dislocation creep of quartz. linear stress-strain rate relations than for dislocation processes, and the importance of grain boundary pro-cesses to creep rates depends on grain size, leading to GSS creep. Greg Hirth's 251 research works with 12,914 citations and 8,474 reads, including: Assessment of quartz grain growth and the application of the wattmeter to predict recrystallized grain sizes Trace amounts of water have long been known to significantly reduce the strength of quartz deforming by dislocation creep, but the effect of carbonic fluids has not been documented experimentally. Greg Hirth & Jan Tullis 1992 (JSG 14, 145-159)and see examples in Tullis et al 2001. Cite . by recrystallization-accommodated dislocation creep and produced smaller recrystallized grains progressively in the course of deformation. Indicates deformation by dislocation creep of quartz however, at slower strain rates and/or temperatures! Interpreted as random by recrystallization-accommodated dislocation creep as well as diffusion creep experimental pressure and conditions. Models of β-quartz involving the water fugacity term climb is important in the creep! 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