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Showing 1 to 20 of 58 for “"Amphibolite Facies"”.
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Metamorphic evolution of ultrahigh-temperature granulite facies and upper amphibolite facies rocks of the Epupa Complex, NW Namibia
… are separated by ductile shear zones: (1) Upper amphibolite facies rocks (Orue Unit) and (2) ultrahigh-temperature (UHT) granulite facies rocks (Epembe Unit). The rocks of the EC are transsected by a large anorthosite massif, the Kunene Intrusive Complex (KIC). The Orue Unit and the Epembe Unit …
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Metamorphic and Tectonic Evolution of the Paleoproterozoic Thompson Nickel Belt, Manitoba
… metamorphic domains consist of a central middle amphibolite-facies zone enclosed by an upper amphibolite-facies zone. The upper amphibolite-facies zone is flanked to the northwest and southeast by granulite-facies zones. The dominant phase of penetrative deformation was responsible for the …
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Calc-Silicate Rocks in the Wollaston Lake Area, Saskatchewan
… , greywacke , and arkose metamorphosed to the amphibolite facies of the Abukuma series form most of the. Group. In the Hollaston Lake area, the Hidden Bay formation of the Daly Lake Group consists of feldspathic quartzite and marble which occurs as layers bounded by calc-silicate rocks, …
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Effects of metamorphism and structure on aeromagnetic anomalies over the Carolina slate belt near Roxboro, North Carolina
… diminish markedly to the WNW near the onset of amphibolite facies. Thus, for similar lithologic mixes in this area, at higher metamorphic grades, magnetic susceptibility contrasts are markedly reduced. Modelling was done to determine the subsurface configuration of a magnetized greenschist …
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Petrography of Precambrian iron formation, Pembina County, North Dakota
… showed them to consist of oxide and silicate facies iron formation interlayered with quartz-biotite schist of Precambrian age. The core recovered from the Akra site contained mineral assemblages of the greenschist and amphibolite facies of regional metamorphism, the metamorphic grade …
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Petrography of the Harvest Lake Area, Quebec, Canada
… with that of the “Staurolite-Almandine Subfacies” of the “Almandine-Amphibolite Facies.” These minerals were determined by hand-sample inspection, by thin-section observations, and by observing powdered samples immersed in refractive oils. </p>
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Fluid-rock interaction on alpine-type ultramafic rocks from the Norwegian Caledonides
… with their country rock. <br> Under greenschist facies conditions the formation of serpentinites is typical, and the formation of ophicarbonates only requires small amounts of CO2. With increasing temperature, the formation of talc-marbles requires higher CO2 amounts. In the brittle to ductile …
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Tectogenesis and metamorphism of the Piedmont from Columbia to Westview, Virginia along the James River
… and sediments were metamorphosed to at least amphibolite facies. During the peak and waning stages of metamorphism, these lighologies experienced 3 or possibly 4 deformational events which occurred while faulting was initiated along the Lakeside fault zone. Retrogressive mineral assemblages in …
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Geology and structure of the Serra Do Mar in eastern São Paulo, Brazil
… of the sillimanite-almandine-orthoclase subfacies of the amphibolite facies of the Barrovian-type facies series of metamorphism is achieved. In the Itatinga Complex migmatites and nebulites are representative of the highest temperature ranges of the amphibolite facies.</p><p>Post-metamorphic …
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Petrology and contact relationships, SW portion PC Mullen Creek mafic complex, Medicine Bow Mts., Wy.
… regional medium-grade metamorphism to form amphibolite facies assemblages in which hornblende has replaced pyroxene, labradorite has remained stable and relict igneous textures are preserved. A later episode of retrogressive low-grade metamorphism has produced locally abundant fractures, …
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Geodynamic evolution and petrogenesis of the neoarchaean Francistown granite-greenstone complex in NE Botswana, SW margin of the Zimbabwe craton
… intrusions have undergone greenschist to lower amphibolite facies metamorphism, but most mafic intrusions have preserved original igneous textures. The Francistown Granite Greenstone Complex likely represents an arc complex that developed along an active continental margin in the Neoarchaean. …
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Tektonometamorphe Entwicklung von Scherzonen im präkambrischen Basement Südindiens
… the South Indian basement, several crustal-scale amphibolite facies shear zones occur between high-grade metamorphic units with a different geological history: the EW-trending Moyar Shear Zone (MSZ) is a zone of predominantly dip-slip transport separating the Archaean Dharwar Craton in the north …
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PRESSURE-TEMPERATURE EVOLUTION OF METAPELITES WITHIN THE ANACONDA METAMORPHIC CORE COMPLEX, SOUTHWESTERN MONTANA
… stability as evidenced by its abundance. These amphibolite facies metapelites equilibrated at or near the solidus.
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PRESSURE-TEMPERATURE EVOLUTION OF METAPELITES WITHIN THE ANACONDA METAMORPHIC CORE COMPLEX, SOUTHWESTERN MONTANA
… stability as evidenced by its abundance. These amphibolite facies metapelites equilibrated at or near the solidus.
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Polyphase tectonics and metamorphism and their relation to movement on the Monte Largo shear zone in the Manzano Mountains, central New Mexico
… upper plate (south of the shear zone) indicate amphibolite facies conditions, 3) these minerals overgrew earlier S1 and S2 fabrics that probably developed during shearing, but were synchronous with development of S3 fabrics that were formed during reoccurring movement on the shear zone, and 4) …
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Crystalline bedrock geology of the lower Susquehanna Gorge: Conowingo to Havre de Grace, Maryland
… Grace Block was metamorphosed and deformed under amphibolite facies conditions during Middle Ordovician to Early Silurian time. It was subsequently thrust upon the Conowingo Block along the Elbow Branch Thrust, probably during the Late Ordovician or Early Silurian. From as early as the Middle …
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An investigation of a polymetamorphic terrain using <sup>40</sup>Ar-<sup>39</sup>Ar geochronology
… separate periods of metamorphism: M1- granulite facies in the Archaean, M2 - amphibolite facies in the Early Proterozoic, and M3 - greenschist to epidote-amphibolite facies in the Mid-Proterozoic. Because of the relatively low blocking temperature of the 40Ar- 39Ar geochronological system in mica …
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The petrology and geochemistry of the minor intrusions in the central metasedimentary belt, Grenville Province, southern Ontario, Canada.
… have been metamorphosed to middle and upper amphibolite facies of low-pressure type, transitional into moderate pressures. Major and trace element contents were determined by X-Ray Fluorescence Analysis. Four distinct geochemical suites have been recognized: a Low Zirconium Suite of …
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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
… 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 promontory.</p>
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Ore mineralogy and paragenesis of a portion of the Great Gossan Lead district, Virginia
… volcanism. Later metamorphism to the epidote-amphibolite facies and subsequent deformation roduced the present mineral assemblage and deformation features.
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