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Showing 1 to 20 of 27 for “"Mylonite"”.
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Monazite Geochronology of the Madison Mylonite Zone and Environs, Southwestern Montana: With Implications for Precambrian Thermotectonic Evolution of the Northern Wyoming Province
… the Snowy shear zone (SSZ) and the Madison mylonite zone (MMZ), South Madison Range, Montana. Comparison of U-Pb and U-Th-Pb ages yielded by monazite grains from both shear zones and zircon rims from SSZ, a new timing for major SE-directed thrusting and formation of the MMZ and SSZ has been …
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Correlation of seismic reflection data with seismicity over the Ramapo, New Jersey, fault zone
Reflection seismic data, mylonite reflectivity, gravity data, and earthquake hypocenters have been integrated into a possible explanation for seismicity in the Ramapo fault area. Seven reflection seismic lines were processed using variations in sorting and residual statics. Single VIBROSEIS sweeps …
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Polyphase Deformation, Thrust-Induced Strain and Metamorphism, and Mesozoic Stratigraphy of the Granite Wash Mountains, West-Central Arizona (Tectonics, Mylonite, Geophysics, Mineralization, Terranes)
… S-C fabrics and other kinetic indicators in mylonites in the thrust zone indicate SW-directed tectonic transport. Slip lines calculated from F2 folds are parallel to the transport direction derived from the mylonites, suggesting thrusting was part of the D2 event. Strain magnitude associated …
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Plagioclase preferred orientation in layered mylonites : evaluation of flow laws for the lower crust
… gabbroic shear zones. Gabbros and layered gabbro mylonites were collected from the Southwest Indian Ridge (SWIR), ODP Hole 735B. Deformation temperatures are constrained by two-pyroxene thermometry, stress is estimated from grain size, and deformation mechanisms are analyzed by microstructure and …
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Plagioclase preferred orientation in the layered mylonites : evaluation of flow laws for the lower crust
… gabbroic shear zones. Gabbros and layered gabbro mylonites were collected from the Southwest Indian Ridge (SWIR), ODP Hole 735B. Deformation temperatures are constrained by two-pyroxene thermometry, stress is estimated from grain size, and deformation mechanisms are analyzed by microstructure and …
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Structural studies and gabbro mylonitization within the Barton Bay Deformation Zone, Geraldton, Ontario /
… The most highly deformed rock is a gabbro mylonite which occurs in the fault zone. The deformation of this gabbro has been traced in stages from a protomylonite to an ultramylonite In which feldspar and chlorite grainslze has been reduced from over 100 microns to as little as 5 microns. …
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Deformation in the striped rock pluton, southwest Virginia
… to several hundred meters. The majority of mylonite zones in the pluton strike east and northeast and are inclined moderately southeast. Cataclasite zones strike northeast and northwest. Deformation is most intense along the southern contact with the Cranberry gneiss where both pluton and …
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Kinematics and timing of the Pinto shear zone, New York Mountains, northeastern Mojave Desert, California
… granitoids beneath the shear zone to protomylonite, mylonite, and ultramylonite near its top. Microstructural studies of mylonite and ultramylonite indicate that deformation occurred over a broad range of decreasing temperatures, from lower amphibolite-uppermost greenschist through lower …
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Geology of an Archean Greenstone Belt at Point Lake, Northwest Territories, Canada
… pillow basalts, limestone, shale and tuff. A mylonite zone separates the gneissic terrane from the supracrustal sequence. The mylonite is interpreted to be a basal decollement along which the supracrustal sequence was emplaced over gneissic terrane. The sequence of lithologies and structures …
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Fluid inclusions: evidence for a counterclockwise P-T trajectory in the Central Maine terrane of South-Central Massachusetts
… garnet-bearing assemblages, recrystallization of mylonites associated with late shear zones to form lower-T and higher-P assemblages, and development of high density CO₂ inclusions in the host rock of the mylonite. Peak conditions in the highest grade rocks were 685 - 780°C and 5-6 kbar; the …
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The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado
… along a NE-trending system of subvertical mylonites and ultramylonites that formed in the Mesoproterozoic and that, in turn, overprinted higher-temperature Paleoproterozoic high strain zones of similar orientation. In this thesis, I distinguish the Colorado Mineral Belt itself from a …
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Isotopic systematics and mass transfer in amphibolite-grade mylonites
… adjacent, actively-deforming quartzofeldspathic mylonite which, with reference to the protolith gneisses less than 30 cm from the gneiss-amphibolite contact, is reduced by 60% of its original concentration of these elements. Where no amphibolite layer is present, quartzofeldspathic mylonites …
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Origin and geological significance of mylonitic shear zones, northern Lucy Gray Range, Clark County, Nevada
… emplacement. In the Lucy Gray Range, a series of mylonite zones is spatially associated with the Beer Bottle Pass pluton. An integrated study involving field and laboratory work, was used to distinguish between three possible scenarios for the origin of the mylonites: (1) intrusion into an active …
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Petrological and geochronological constraints on the metamorphic evolution of high-pressure granulites and eclogites of the Snowbird tectonic zone, Canada
… The focus of this study is the East Athabasca mylonite triangle (EAmt), a well-exposed terrane of granulite facies mylonitic rocks along the trace of the Snowbird tectonic zone in northern Saskatchewan. This study focuses on the 400 km² Southern Domain of the EAmt, which contains a spectacular …
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The Fries Fault near Riner, Virginia: an example of a polydeformed, ductile deformation zone
… the northwest. A 0.8-1.2 km wide subzone of protomylonite within the Little River Gneiss grades into a 0.5-1.0 km wide mylonite subzone, the latter containing narrow bands of phyllotactic ultramylonite ranging in width from centimeters to tens of meters. Mylonitization is reflected by a marked …
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Tectogenesis of the Hylas zone and eastern Piedmont near Richmond, Virginia
… to the northwest produced a zone of protomylonite, mylonite and ultramylonite from felsic gneiss and amphibolite. The thrusting event, which initiated retrograde metamorphism to greenschist facies, carried an allochthonous plate of coarse-grained, locally porphyry tic Petersburg(?) Granite …
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Die Gold-Kupfer-Mineralisationen südlich von Rehoboth, Namibia
… Quarz, Karbonat und Chlorit assoziiert sind. Mylonite der Scherzonen sind durch Albitisierung, Serizitisierung und teils durch eine Illitisierung gekennzeichnet. Es liegen zwei Arten der Au-Cu-Mineralisation vor. Bei der Vererzung der Swartmodder Kupfer Mine handelt es sich um eine …
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Structural analysis of brittle deformation features along Grenvillian shear zones in southeastern Ontario
… boundary thrust zone (CMBbtz) and Robertson Lake mylonite zone (RLmz), are investigated to understand the brittle deformation history of this intraplate region. Evolution of brittle deformation is interpreted from detailed mapping and characterization of joint, fault and vein patterns in …
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Aspects of Deformation and Strain in the Appalachian Fold -Thrust Belt (New York) and the Shear Zones of the Sveconorwegian Orogen (Norway)
… for kinematic analysis in samples of Precambrian mylonite from shear zones in the Sveconorwegian orogen of southeastern Norway. The goal of this work was to provide constraints on transport directions in a case where outcrop-scale mineral-stretching lineations are missing or ambiguous, and quartz …
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The thermal and metamorphic evolution of the Northern Highlands Terrane, Scotland
… in the NHT, in lower initial temperature mylonite zones shear heating could be more significant.
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