Global ETD Search
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 22 for “"mylonites"”.
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Isotopic systematics and mass transfer in amphibolite-grade mylonites
… amphibolite layer is present, quartzofeldspathic mylonites display a similar depletion in Fe and Mg, but also carry textural and geochemical evidence for fluid flow on a millimeter to centimeter scale (e.g. foliation-parallel quartz veins walled by monomineralic layers of plagioclase or …
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Pressure, temperature, and stress conditions of Southern Alpine Fault (New Zealand) mylonites
… deformation ages vary along strike by ~15 m.y.. Mylonites collected from two southern creeks near Haast, NZ, display a uniform recrystallized grain size of ~11 𝜇m in mylonitic quartz indicating differential stress values in the south of ~100 MPa, roughly twice the stress values observed in the …
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Flow Properties of Moine Thrust Zone Mylonites in Northern Assynt, NW Scotland
Quartz-rich mylonites present along the Moine Thrust Zone are well suited for the application of various analytical techniques designed for investigating the flow processes by which rock deformation occurred. These analytical techniques were applied to a suite of samples from the footwall and …
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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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Origin and geological significance of mylonitic shear zones, northern Lucy Gray Range, Clark County, Nevada
… three possible scenarios for the origin of the mylonites: (1) intrusion into an active shear zone, (2) post-emplacement ductile deformation, and (3) mylonitization during and as a consequence of forcible pluton emplacement. Observations made during this study indicate that forcible intrusion is …
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Structural and metamorphic evolution of a gneiss terrain in the Namaqua Belt near Onseepkans, South West Africa
… and the core contains a 2 km - 7 km wide belt of mylonites. Two sets of folds (D₅ and D₆) have been formed in the zone of reorientation in the northern block. The D₅ folds are northeast trending en-echelon structures up to 30 km long and the interference pattern produced by superimposed northwest …
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Analysis of the Cabin Canyon shear zone in the Virgin Mountains : implications for an early accretionary province boundary and later transpressional zone.
… dextral, northwest-side-up, oblique shear. The mylonites within the zone are comprised of amphibolites, granodiorites, a variety of meta-sedimentary rocks, and leuco-pegmatite dikes. The oldest rocks involved in shearing are similar to ~1.7 Ga of the Grand Canyon, but mylonitization is inferred …
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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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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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Correlation of seismic reflection data with seismicity over the Ramapo, New Jersey, fault zone
… Taconic suture displays fewer hypocenters and mylonites, in agreement with an assumed model of mylonite development possibly associated with obduction of continental crust. The mylonite zones in the basement may serve as local areas of crustal weakness for seismic activity occurring in the area.
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Analysis of seismic reflection data over the Sanford Triassic Basin, Chatham and Lee Counties, North Carolina
… > 0.7 sec) are attributed to meta volcanics and mylonites of the Carolina Slate Belt.
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The geological record of oceanic crustal accretion and tectonism at slow-spreading ridges
… and geothermometry of abyssal peridotite mylonites recovered from fault zones at slow-spreading ridges.
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Grain size evolution and strain localization in deformed marbles
… which is observed in the finest grained mylonites closest to the thrust contact. In Chapter 4, laboratory deformation experiments are used gain insight into the kinetics of microstructural evolution in calcite-rich rocks. The grain size evolution rates measured in experiments correlate …
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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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Microstructural, geochronologic and thermochronologic evidence for both Paleo- and Mesoproterozoic displacement across the Gneiss Canyon shear zone : lower Granite Gorge, Grand Canyon, Arizona
… Yavapai orogeny. Newly described retrograde D3 mylonites consists of discrete (cm to m-scale) zones, which occur within, and represent reactivation of the wider GCSZ. D3 microstructures indicate lower temperature dynamic recrystallization of quartz, as well as brittle deformation suggesting …
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Controls on the diversity of the fault slip styles at the brittle-ductile transition: examples from the Cape Fold Belt, Nuy Valley, South Africa
… ways, with quartz-cemented breccias, limestone mylonites, abundant quartz veining and cataclasites attesting to faulting occurring by a diversity of slip style, which allows investigating how the interplay of the controlling factors lead to the observed diversity of fault rock. Through mineral …
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Constraining Metamorphic and Tectonic Evolution in Convergent Terranes: How Trace Elements and Mineral Inclusions Shape Mechanical and Reconstructive Models
… of the Ti-in-quartz thermobarometer in quartz mylonites has led to mixed results due to the low-Ti resetting that occurs with dynamic recrystallization. We applied defect energy simulations and took a global assessment of deformed quartz trace element chemistries to infer that sweeping grain …
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Tektonometamorphe Entwicklung von Scherzonen im präkambrischen Basement Südindiens
… MSZ, BSZ and PSZ: Sm-Nd mineral ages from gneiss-mylonites imply a first stage of early Pan-African shearing in the MSZ ~745 Ma ago (garnet/plagioclase-hornblende-pairs: 743 ± 13 Ma, 747 ± 75 Ma) and in the BSZ ~730 Ma ago (garnetwhole rock-pair: 726 ± 9 Ma). This tectonic stage immediately …
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Metamorfismo varisico dell’Unità tettonica del Monte Grighini,Sardegna centrale
… complex related to a shear zone marked by ultramylonites and cataclasites. Geological map in scale 1:25000 of the Monte Grighini Complex has been done by combining geo-petrographical data with previous geological and structural data (Musumeci et al., under revision). A lito-stratigraphic column …
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