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Showing 1 to 20 of 32 for “""Polyphase deformational history""”.
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New stratigraphy, polyphase deformational history and basement-involved thrust belt model for the Proterozoic Uncompahgre Group and Vallecito Conglomerate, Needle Mountains, Colorado
… provide insight into the depositional and deformational history of one of the best exposed of these Paleoproterozoic cover successions. This study documents a gradational contact between the basal Vallecito Conglomerate and the overlying Uncompahgre Group and offers a transgressive …
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History and timing of polyphase Proterozoic deformation in the Manzano thrust belt, central New Mexico
… is an important place to better characterize polyphase deformation and magmatism related to the assembly of Laurentia, particular the 1.65-1.60 Ga Mazatzal orogeny and the later 1.4 Ga thermo-tectonic event. This study focuses on the Los Pinos Mountains, near the southern end of the Manzano …
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Polyphase Proterozoic tectonometamorphic history of the Taos Range, northern New Mexico
… preserve components of a protracted tectonic history involving pre-1.7 Ga, 1.65 Ga, 1.4 Ga, and possible 1.1 Ga tectonism. The southern Taos Range is a 1.76 – 1.7 Ga volcano-plutonic complex with tectonically interlayered remnants of the Hondo Group. Similar rock types are exposed in the …
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Proterozoic thermal and deformational history and geochemical evolution of the 1.4 Ga Priest pluton and its aureole
… +/- 0.01 ga Priest pluton provide evidence for a polyphase Proterozoic metamorphic history in central New Mexico. This history involved pre-, syn-, and post-emplacement metamorphic mineral growth. The Priest pluton contact aureole is 1.2 kilometers wide and is characterized by two isograds (first …
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Banded metasiltstones in Trigo Canyon : the story they tell about the Proterozoic deformational history of the Manzano Mountains
… because they preserve a record of early history of the Manzano thrust belt. The rocks are newly interpreted as mylonitized metasiltstones with a volcanic source based on bulk composition (~70% SiO2, ~15% Al2O3). The orientation of the rocks and the map pattern suggest refolded folds that …
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Polyphase deformation and metamorphism in the Penobscot Bay Area, Coastal Maine
… the adjacent Bucksport terrane, shared a common history of four phases of ductile deformation (D₁, D₂, D₃, and D₄) and interdeformational metamorphism and granitic plutonism. D₁ (early Acadian ?) produced tight to isoclinal folds and an axial plane foliation that deform all three metasedimentary …
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STRUCTURAL AND KINEMATIC INVESTIGATION OF THE DADEVILLE COMPLEX-BREVARD ZONE CONTACT (SOUTHERN APPALACHIANS): POLYPHASE EMPLACEMENT OF AN ALLOCHTHONOUS TERRANE ON THE LAURENTIAN MARGIN
… F1 to create doubly-plunging hinges. Both deformational events occurred during the Acadian/Neoacadian orogeny at peak amphibolite-facies metamorphism. The DC was accreted onto Laurentia in two stages with distinct shortening directions, potentially due to rotation along the Alabama …
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Geology of the Snip Mine, and its relationship to the magmatic and deformational history of the Johnny Mountain area, northwestern British Columbia
The Snip mine consists of an auriferous southwest-dipping shear vein system in a north-dipping Triassic greywacke-siltstone sequence altered with abundant vein let and pervasive biotite. The deposit, termed the Twin zone, is the largest of numerous shear veins in the mine workings. It contains just …
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Structural constraints on the exhumation of the Tso Morari Dome, NW Himalaya
… Morari area reveals evidence for five distinct deformational events. Rather than simple, one step processes envisioned by investigators in many ultrahigh-pressure terrains, exhumation of the Tso Morari culmination was a polyphase process. From >90 km to mid-crustal depths, exhumation was …
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Basement and Cover Structural Analysis Along the Eagle River Gorge, Sawatch Range, Colorado
… Paleozoic sedimentary rocks with a complex history of ductile and brittle deformation.</p> <p>The goal of this study is to conduct analyses of brittle structures that occur in the basement and cover units to determine geometric relationships between the structures, provide a detailed …
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The structural, metamorphic and thermal history of the Sonnblick Dome, southeast Tauern Window, Austria
… Although this alteration is associated with syn-deformational fluid infiltration, a spatial relationship between reaction site and deformation suggests that the energy associated with deformation contributed to reactions during shear zone formation. As a response to tectonic thickening, pressures …
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Geologic History and the Timing of Mineralization at the Haile Gold Mine
… 1.17 Ma. These measurements document the complex deformational history of the Haile deposit but based on interpretations of geochronological data presented in this study was not the driving force behind Au mineralization.</p>
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Structural Style and Regional Comparison of the Paleoproterozoic Ketyet River Group in the Region North-Northwest of Baker Lake, Nunavut
… Churchill Province, have been affected by polyphase deformation and metamorphism causing structural complexity and confusion regarding the age and affiliation of rock units. This study improves the stratigraphic and structural understanding of the Paleoproterozoic Ketyet River group and …
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Fluid/rock Interaction History of a Faulted Rhyolite-Granite Contact, Eastern Rhine Graben Shoulder, SW-Germany : Alteration Processes Determined by Sr- Pb-Isotopes, Th/U-Disequilibria and Elemental Distributions
The alteration history of the Schauenburg fault has been investigated with isotope and element distributions across the faulted granite-rhyolite contact. The Schauenburg fault zone is situated along the eastern Rhine Graben shoulder, close to Heidelberg (SW-Germany). Major and trace element …
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The geology of the area east of Pofadder with emphasis on shearing associated with the Pofadder lineament, North West Cape
… on the role of shearing in the deformation history of the area. The study area occurs within the Namaqualand Metamorphic Complex and consists of gneisses, schists and quartzites. These rocks are overlain to the south by the Dwyka Formation of the Karoo Sequence. The rocks of the Namaqualand …
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Tectono-thermal evolution of Gjelsvikfjella, Western Dronning Maud Land, Antarctica
… in Dronning Maud Land preserves a high-grade polyphase tectono-thermal history. This belt has traditionally been interpreted as a Mesoproterozoic-age (1.3-0.9 Ga) mobile belt that was later affected by thermal overprint associated with little or no deformation during the Neoproterozoic …
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Geology of the central Moresby Island region, Queen Charlotte Islands, (Haida Gwaii) British Columbia
… study analyzes the structural and stratigraphic history of the central Moresby Island area, and correlates this history with ongoing and previous studies in the Queen Charlotte Islands. The stratigraphic succession preserved in central Moresby Island comprises marine volcanic and sedimentary …
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Microstructural and crystallographic fabric analysis of stretched-pebble conglomerates in central Vermont
… were analyzed to investigate the complex deformational history associated with a polydefonned area. Microstructural observations and crystallographic fabric techniques were used for kinematic analysis, and to relate the development of microstructures and lattice preferred orientations to …
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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.
… mylonitic foliation that records a complex history of movement and strain within the Virgin Mountains. The overall movement history is interpreted to involve a combination of northwest shortening deformation and dextral, northwest-side-up, oblique shear. The mylonites within the zone are …
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Proterozoic Farwell Mountain-Lester Mountain suture zone, northern Colorado : subduction flip and progressive assembly of arcs
… this study is the correlation of metamorphic and deformational fabrics among four field subareas (Farwell Mountain, Lester Mountain, Mica Basin, and the Soda Creek–Fish Creek shear zone), in an attempt to investigate the history and character of the proposed "suture zone." Steepening and …
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