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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 106 for “"Shear zones"”.
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Thermal Structure of Mid-Crustal Shear Zones
… (Td) correlate to Tm, indicating that ductile shearing occurred during peak Tm. In the Scottish Caledonides, Td and Tm increase from foreland to hinterland, potentially indicating a right way up thermal structure; chapter two presents Td and Tm associated with the region around the SBT. Above …
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Piezometry and Strain Rate Estimates Along Mid-Crustal Shear Zones
… and grainsize evolution along mid-crustal shear zones allows for the estimation of tectonic driving stresses and strain rates acting in the mid-crust. Quartz-rich tectonites from three exhumed mid-crustal shear zones, the Main Central Thrust (MCT; Sutlej valley, NW India), South Tibetan …
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Shear zones of the Maud Belt, Antarctica : kinetics and deformation mechanisms
… and strain is commonly localized within shear zones. The two study areas H.U. Sverdrupfjella and Neumayerskarvet mainly consist of paragneisses and orthogneisses and in places migmatites and granite intrusions. The orthogneisses and paragneisses mainly consist of coarse to medium grained …
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Structural analysis of brittle deformation features along Grenvillian shear zones in southeastern Ontario
Brittle features along two prominent shear zones in the Grenville Province of southeastern Ontario, the Central Metasedimentary Belt boundary thrust zone (CMBbtz) and Robertson Lake mylonite zone (RLmz), are investigated to understand the brittle deformation history of this intraplate region. …
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Origin and geological significance of mylonitic shear zones, northern Lucy Gray Range, Clark County, Nevada
… 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 shear …
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Emplacement of the Santa Rita Flat pluton and kinematic analysis of cross cutting shear zones, eastern California
… emplacement to post-emplacement transpressional shearing, and consists of manuscripts that make up three chapters. The first chapter addresses the emplacement of the Santa Rita Flat pluton using anisotropy of magnetic susceptibility (AMS). The second chapter describes the kinematic analysis of …
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Study of fault gouge influences on mechanical and frictional behavior of granular shear zones using the distinct element method
Studies of fault gouge and its role in shear zone deformation are the key to understanding the mechanics of earthquakes and fault zone evolution. With the advantage of exploring the micromechanical process of gouge deformation in "real time", the combination of the Distinct Element Method (DEM) and …
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Proterozoic evolution of the Zuni Mountains, New Mexico: Peridotites, granites, rhyolites, shear zones, and a reactivation history through the present
… and rhyolites were followed by a younger shearing event. A 10 km long shear zone trends WNW, dips 60 degrees south and has a SW-plunging mineral elongation lineation. Shear sense is extensional (top-to-the-SW), typically with a dextral component. Microstructural data and mineral …
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Structure and geochronological constraints on the ductile deformation observed along the Gaoligong Shan and Chong Shan Shear Zones, Yunnan (China)
… in between the Sagaing fault and the Ailao Shan Shear Zone: the Gaoligong Shan Shear Zone (GSSZ) and the Chong Shan Shear Zone (CSSZ) in Yunnan, China. The presently inactive GSSZ is an important dextral Cenozoic (and possibly latest Mesozoic) ductile shear zone and appears to be the only …
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The Box Ankle and Ocmulgee shear zones of central Georgia: a study of geochemical response to Southern Appalachian deformation events
… to high grade deformation from both fault zones is observed. The response of zircon U-Pb systematics in these fault zones provides data on the effects of Pb loss versus U gain models, dissolution processes, and overgrowth binary mixing models from within selected mylonitized bulk rock …
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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)
… 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 does not …
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The interaction between chemical and mechanical processes during metamorphism: a microstructural and petrologic study of amphibolite shear zones, Cheyenne Belt, Southeastern Wyoming
Shear zones which deform margins of amphibolite boudins in the Cheyenne Belt, SE Wyoming, record a full strain transition from relatively undeformed amphibolite which has relict igneous textures to mylonitic amphibolite with a strongly developed L-S tectonic fabric. The strain transition is marked …
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Tracking multistage deformation within an ultrahigh-pressure terrane: zircon and monazite microstructures and petrochronology from shear zones of the Western Gneiss Region, Norway
… style ofdeformation (i.e. focused in discrete shear zones versus distributed strain) varies acrossthe WGR. Here we present split-stream laser-ablation inductively coupled massspectrometry (LA-ICP-MS) geochronology and trace-element abundances, Ti-in-zirconthermometry, and EBSD data from zircons …
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U-Pb geochronology and structural geology across major shear zones of the Southern granulite terrain of India and organic carbon isotope stratigraphy of the Gondwana coal basins of India : their implications for Gondwana studies
… evolution of continental lithosphere in general. Shear zones that cross the boundaries of continental fragments provide 'piercing points' in fitting the fragments back together. To realize this, the kinematics and the timing of major shear zones need to be determined. The first part of this …
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History of the fluids associated with the Proterozoic Star Lake lode-gold deposit, northern Saskatchewan, Canada
… an array of subparallel northeasterly-striking shear zones. Gold mineralization was fracture-controlled, and the main stage of deposition occurred during late fracturing episodes within the shear zones. The majority of the fluid inclusions trapped within the vein-quartz are of secondary origin, …
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Structural and metamorphic evolution of an area around Kakamas and Keimoes, Cape Province, South Africa
… comprises some 1800 km2 along the Orange Several shear zones divide the area into a number of blocks; from west to east these are the Kakamas Shear Zone, the Duivelsnek Shear Zone, the Neusspruit Lineament, the Braamfontein Shear Zone and the Cnydas Shear Zone. Three folding phases were …
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Localization instability and the origin of regularly-spaced faults in planetary lithospheres
… but is instead localized on faults and ductile shear zones. In some regions such as the Central Indian Basin or martian ridged plains, localized shear zones display a characteristic spacing. This pattern can constrain the mechanical structure of the lithosphere if a model that includes the …
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The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado
… higher-temperature Paleoproterozoic high strain zones of similar orientation. In this thesis, I distinguish the Colorado Mineral Belt itself from a Proterozoic 'Colorado Mineral Belt shear zone system' that includes the Homestake, Gore Range, St. Louis Lake, and Idaho Springs-Ralston shear zone …
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Deformation in the striped rock pluton, southwest Virginia
… is cut by pervasive centimeter-scale cataclasite zones and ductile shear zones that vary in width from a few millimeters 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 …
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