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Showing 1 to 20 of 67 for “"Plutons"”.
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U/Pb Zircon Ages of Plutons from the Central Appalachians and GIS-Based Assessment of Plutons with Comments on Their Regional Tectonic Significance
… U/Pb ages of zircons were obtained for ten plutons (Leatherwood, Rich Acres, Melrose, Buckingham, Diana Mills, Columbia, Poore Creek, Green Springs, Lahore and Ellisville) within Virginia. These plutons are distinct chemically, isotopically, and show an age distribution where felsic rocks …
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Petrogenesis of Sierran plutons : a petrologic and geochemical investigation into the origin and differentiation of granodioritic plutons of the central Sierra Nevada batholith, California.
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Science.
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Petrography of xenolith zones in the Black Face-Ames plutons, western San Juan Mountains, Colorado
<p>The middle to late Tertiary Black Face-Ames plutons are irregularly-shaped, intrusive bodies located in the San Miguel Mountains of southwestern Colorado. The Ames pluton is generally a composite sill; the Black Face pluton is an asymmetric laccol1th. The two plutons are probably joined at …
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Strain Analysis Across the Margins of the Elkahatchee and Coley Creek Plutons, Alabama Eastern Blue Ridge: Implications for the Alexander City Fault
… intruded by Ordovician-Mississippian granitic plutons. Two of these plutons, the Elkahatchee Quartz Diorite and Coley Creek orthogneiss exhibit zones of high strain, evidenced by mylonitic fabrics, ductile deformation of feldspar grains, grain size reduction, and changes in mica content at …
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U-Pb dating of granites from the Charlotte belt of the southern Appalachians
New U-Pb zircon ages from plutons in the Charlotte belt of the southern Appalachians have provided evidence of Cambro-Ordovician and Siluro-Devonian magmatic activity. Several U-Pb zircon ages of Cambro-Ordovician plutons predate their Rb-Sr whole rock ages by as much as 60 m.y., suggesting a post …
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Space-Time Analysis of Magmatism: Evidence for a Early Cryogenian Plume Track in Eastern Laurentia
… In this study U/Pb zircon ages of several plutons were determined using secondary ion mass spectrometry. The ages suggest two episodes of magmatism. An older episode (739 to 745 Ma) of magmatism includes White Oak Creek, Suck Mountain, and Amisville plutons. The younger episode (613 to 694 …
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AN IMBRICATE MID CRUSTAL SUTURE ZONE: THE MOJAVE-YAVAPAI PROVINCE BOUNDARY IN GRAND CANYON, ARIZONA
… composition of zircons from both the oldest plutons and metasedimentary rocks in Grand Canyon. My results show that the Vishnu Schist does not support suturing. Paradoxically, plutons east and west of the Crystal shear zone support suturing based on different U-Pb-Hf isotopic characteristics …
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Pluton source varition over two magmatic pulses in the White-Inyo range, central-eastern California : implications for paleozoic and mesozoic tectonic reconstructions
… REQUEST.] This dissertation uses compositions of plutons in the White-Inyo Range (WIR) of central-eastern California, which is an important tectonic boundary as it is the easternmost extent of the Mesozoic Cordilleran arc and the western edge of Basin and Range extension. The main goal of this …
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Thermochronology and geobarometry of the Granite Mountains, southeast California: Exhumation of a plutonic complex during collapse of the Sevier orogen
… Mountains indicate exhumation of mid-crustal plutons during Late Cretaceous extensional tectonics. U/Pb zircon and 40Ar/39Ar ornblende ages indicate intrusion, crystallization, and geologically instantaneous cooling through 500°C at ∼75 Ma. K-feldspar multi-diffusion domain modeling …
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Petrografia, litoquímica, química mineral e termobarometria de rochas cálcioalcalinas de alto K de textura porfirítica, ediacaranas, no extremo NE da Província Borborema (NE do Brasil)
… of the Borborema Province, NE Brazil. The plutons are represented by monzogranites wich have porphyritic facies with phenocrysts of K-feldspar with sizes between 5 and 15 cm. The K-feldspar, plagioclase and quartz are the dominant paragenesis; while the biotite and amphibole are the main …
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Decarbonization related to continental arc magmatism as a possible mechanism for Cretaceous warming
… and contact metamorphism of carbonates around plutons. Bedrock maps of the North American Cordillera (a region of active continental arc magmatism during the Cretaceous), the relative locations of the carbonates, the Cretaceous plutons, and the calculated "decarbonation zones"around the …
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Tectonic evolution of the Western Limassol Forest Complex, Cyprus
… intruded by multiple ultramafic and gabbroic plutons and swarms of mainly NE-SW trending dykes. The entire complex has been sheared along E-W trending serpentinite shear zones, the orientation of which indicate sinistral displacement. The various styles of deformation from ductile to brittle, …
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Structural and petrologic aspects of the emplacement of granitoid plutons : case studies from the western margin of the Joshua Flat-Beer Creek-Pluton (White-Inyo Mountains, California) and the Flasergranitoid zone (Odenwald, Germany)
… measurements support the field observations. The plutons of the Flasergranitoid Zone in the Crystalline Odenwald Zone intruded around 325 Ma ago. Intrusion conditions of five dioritic to granitic plutons were determined with hornblende geothermobarometry. The plutons intruded into a depth of 13 to …
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Structural setting and petrogenesis of Silurian granites in the Caledonides of northern Scotland
… and Naver nappes, contain a series of granitic plutons. The Rogart, Strath Halladale and Helmsdale granites have been studied using field and microstructural fabric analysis. Their emplacement mechanisms and pre, syn or post-tectonic status with respect to phases of Caledonian ductile …
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Compositional Diversity in Arcs: A Record of Magmatic Processes in the Peru Coastal Batholith, Ica
<p>Peruvian granitic plutons display evidence for crustal recycling and magma mixing. Evidence of physical and chemical processes operating during the formation of the Ica-Pisco complexes involves magma mixing and mingling as result of felsic and mafic interactions. Evidence of crustal recycling …
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Shearing on the Great Glen Fault: Kinematic and Microstructural Evidence Preserved at Different Crustal Levels
… displacing c. 425 Ma isotopically dated granitic plutons. Stewart et al. (2001) argued that dikes fed by these plutons were sinistrally sheared by the GGF while in the sub-magmatic state, suggesting continuous strike-slip motion on the GGF by 425 Ma. Strike-slip offset post-dating overlying …
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Mineralogical, chemical and isotopic diversity in plutonic rock suites from the Coastal Maine Magmatic Province:the role of source region heterogeneity, tectonic setting and magmatic processes
… the base of the crust. The diversity of granitic plutons reflects changes in the mineral assemblages present during partial melting, and in some instances, modification as a result of mixing/mingling with mantle melts. The second chapter examines the effect of accessory minerals on the initial Pb …
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Pluton emplacement, aureole deformation and metamorphism, and regional deformation within the central White-Inyo Range, Eastern California
… rocks which has been intruded by granitic plutons associated with the Mesozoic Sierra Nevada intrusive suites to the west. My dissertation involves a characterization of the pre-plutonic regional deformation within the central White-Inyo Range and an understanding of the deformation of the …
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Geology of the Bottle Lake Complex, Maine
… synclinorium in east-central Maine. The two plutons exposed within the Complex are reversely zoned in their mineralogy, major and trace element compositions. Each intrusive exhibits characteristic features including the abundance of amphibole and mafic xenoliths as in the Passadumkeag River …
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Proterozoic thermal and deformational history and geochemical evolution of the 1.4 Ga Priest pluton and its aureole
… pluton is part of the suite of 1.4 Ga granitic plutons in North America. The pluton is a corundum normative, peraluminous, K-feldspar megacrystic granodiorite to quartz monzonite. The Priest pluton is characterized by high Mg/Mg+Fe and high abundances of Al2O3, CaO, and large ion lithophile …
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