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 44 for “"Paleoproterozoic"”.
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The Geobiology of the Paleoproterozoic Belcher Group, Nunavut, Canada
… are a collection of microbial organisms from the Paleoproterozoic (~2.0 to 1.8 Ga) Belcher Group from the Belcher Islands, Nunavut, Canada. The Belcher Group is exceptionally well-preserved, having avoided deep burial or strong deformation during the Trans-Hudson orogen. The 6-9 km thick Belcher …
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Metamorphic and Tectonic Evolution of the Paleoproterozoic Thompson Nickel Belt, Manitoba
… which was tectonically reworked during the Paleoproterozoic Trans-Hudson orogeny. This work represents the first comprehensive regional metamorphic study of the belt. Three nested metamorphic domains are present in the Thompson Nickel Belt which are elongate subparallel to the regional …
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Chemostratigraphy of the Early Paleoproterozoic carbonate successions (Kaapvaal and Wyoming cratons)
Evidence of three glaciations in Paleoproterozoic successions of North America and at least one on three other continents, suggests that these glaciations were of global extent. In common with the Neoproterozoic record, carbonates cap the glacials. However, the relationship between biogeochemical …
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Depositional facies and detrital composition of the paleoproterozoic Et-Then group, NWT, Canada : signature of intracratonic indentation tectonics
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994.
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U-Pb geochronological constraints on the tectonic and thermal evolution of paleoproterozoic crust in the Grand Canyon, Arizona
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996.
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Structural Style and Regional Comparison of the Paleoproterozoic Ketyet River Group in the Region North-Northwest of Baker Lake, Nunavut
Archean to Paleoproterozoic rocks of the Rae Craton, Western 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 …
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The stratigraphic and structural controls on copper-gold mineralization at Cassenha hill prospect, within the Archean to Paleoproterozoic Angolan shield, Congo craton, South Western Angola
… Central Eburnean Zone (CEZ) and consists of Paleoproterozoic metasedimentary rock sequences which have been intruded by Eburnean granitoids at ± 2.1 Ga. The prospect itself comprises an area of 180 Km2 and has been intermittently explored since 2005 by Rift Valley Resources (RVR) and its …
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Petrogenetic and Geochemical characterization of the Spinghar Crystalline Complex in North-Western Pakistan
… between the studied granitoids and adjoining Paleoproterozoic granites from the lesser Himalayan belt suggests that they were formed in a similar syn-collisional to arc related tectono-magmatic environment during the Paleoproterozoic.<br/><br/>Amphibolite dykes of alkaline to subalkaline …
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Proterozoic Farwell Mountain-Lester Mountain suture zone, northern Colorado : subduction flip and progressive assembly of arcs
The mechanisms by which juvenile Paleoproterozoic continental crust was derived from the mantle, accreted to southwestern Laurentia ca. 1.78-1.68 Ga, and stabilized as new continental lithosphere have been much debated. This study addresses the problem by assessing the proposed Paleoproterozoic …
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The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado
… 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 Proterozoic 'Colorado Mineral Belt shear zone system' that includes the Homestake, Gore Range, St. Louis Lake, and Idaho …
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Basement and Cover Structural Analysis Along the Eagle River Gorge, Sawatch Range, Colorado
… the Rocky Mountains of central Colorado exposes Paleoproterozoic basement and overlying 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 …
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Relative Timing of Porphyroblast Growth and Peak Metamorphism in the Lower Granite Gorge, Grand Canyon, Arizona.
… of the Grand Canyon represents an important Paleoproterozoic tectonic boundary between the Mojave and Yavapai provinces, and records west-side-up shear and NW-SE contraction at elevated temperature (~600 degrees Celsius). Movement took place on subvertical NE-striking foliation that forms the …
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Bedrock and surficial geology of the southern half of the Montezuma 7.5' quadrangle, central Colorado Front Range, Colorado, USA
… and Mesoproterozoic history of the area. The Paleoproterozoic geologic history in the southwestern United States is characterized by the Yavapai (~1.71-1.68 Ga) and Mazatzal (~1.65-1.60 Ga) orogenies, which both involved terrane accretion along the southeastern margin of Laurentia. Within the …
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STRUCTURAL, THERMOCHRONOLOGICAL, AND STRATIGRAPHIC CONSTRAINTS ON THE EVOLUTION OF THE CLEARWATER METAMORPHIC CORE COMPLEX, IDAHO
… zones: an internal zone that consists of Paleoproterozoic anorthosite and basement schist, and an external zone that consists of Archean to Paleoproterozoic intrusive bodies, basement metasediments, and metasediments of the Mesoproterozoic Belt Supergroup. This thesis is focused on …
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STRUCTURAL, THERMOCHRONOLOGICAL, AND STRATIGRAPHIC CONSTRAINTS ON THE EVOLUTION OF THE CLEARWATER METAMORPHIC CORE COMPLEX, IDAHO
… zones: an internal zone that consists of Paleoproterozoic anorthosite and basement schist, and an external zone that consists of Archean to Paleoproterozoic intrusive bodies, basement metasediments, and metasediments of the Mesoproterozoic Belt Supergroup. This thesis is focused on …
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Paleoenvironmental Reconstruction of an Upper Ordovician Rocky Shoreline: The Lindsay Formation of Heywood and Partridge Islands, Ontario
… preserve a major unconformity between the Paleoproterozoic Bar River and Lorrain Formation quartz arenite and Upper Ordovician Lindsay Formation carbonate and mudrock. The Lindsay Formation strata record two transgressive pulses of an epeiric sea that flooded the North American continent …
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Geologic and tectonic evolution of the Manzano Peak Quadrangle, central New Mexico
… Basin of the Rio Grande Rift. During the Paleoproterozoic, the Precambrian rocks exposed in the range were accreted onto the "southward" growing Laurentian craton (southward by current day coordinates). Regional plutonism occurred during accretion (ca. 1.65 Ga) and also in the …
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History and timing of polyphase Proterozoic deformation in the Manzano thrust belt, central New Mexico
… and is therefore an ideal place to characterize Paleoproterozoic deformational events. Building on a large amount of prior work to the north, this study allows for a complete cross section to be drawn for the Manzano thrust belt and for the development of a more complete stratigraphic …
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Reconstructing local redox conditions, mineral precipitation processes and nutrient availability in seawater during deposition of the Transvaal Supergroup, South Africa
… precipitates. The trace metal content from Paleoproterozoic greenalite is then used to predict Paleoproterozoic ocean metal content. The findings from this study show that the microbial carbonates from the Campbellrand Subgroup exhibit seawater-like post-Archean Australian Shale patterns, …
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