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Showing 1 to 18 of 18 for “"Trachyte"”.
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Petrology of the Cenozoic igneous rocks of the Lytle Creek area, Bear Lodge Mountains, Wyoming
… data is used to interpret the Cenozoic phonolite trachyte rock association.</p> <p>Cenozoic igneous activity in the Lytle Creek area appears to have been a response to the Laramide orogeny 80-40 m.y. B.P. The majority of the rocks were emplaced as laccoliths and sills at the Pahasapa …
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Petrology and alteration in the core of the Bear Lodge Tertiary intrusive complex, Bear Lodge Mountains, Crook County, Wyoming
… intrusive core of the complex is mostly alkali trachyte but latite is abundant in the southern portion of the complex. Phonolite, pseudoleucite trachyte porphyry, and carbonatite dikes cut across the core. Precambrian granitic rocks and lower Paleozoic sedi mentary rocks flank the intrusion and …
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Geology and petrology of the Devils Tower, Missouri Buttes, and Barlow Canyon area, Crook County, Wyoming
… the Missouri Buttes rock as foid-bearing alkali trachyte and anal cime phonolite and the Devils Tower and Barlow Canyon rocks as analcime phonolite.</p> <p>Associated alloclastic breccia with a crystal-charged volcanic glass matrix, surrounding depressions representing collapse of igneous …
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Petrology of the Cenozoic phonolites and related rocks of the Houston Creek area, Bear Lodge Mountains, Wyoming
… are classified as phonolite, phonolite porphyry, trachyte porphyry, sodalite-bearing phonolite and altered felsite. These hypabyssal rock types are characterized by porphyritic volcanic textures and trachytic to pilotaxitic fabrics. They contain phenocrysts of sanidine, aegirine-augite, hauyne, …
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Studies of Magmatic Systems
… different petrological tools: 1) Origin of Ponza trachyte was studied combining data from MI with trends predicted by thermodynamic modeling. MI data were compared with known phase relations in the ternary feldspar and anorthite-diopside-albite systems to constrain the parameters used in the …
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Petrology of the Cenozoic igneous rocks of the Tinton district, Black Hills, South Dakota - Wyoming
… that include a stock of quartz latite/quartz trachyte porphyry, an alkalic ring dike complex, lamprophyre dikes and intrusive breccia.</p> <p>Precambrian rocks are represented by a sequence of metapelites thst have been intruded by metabasite and granitic pegmatite dikes. The schistosity of …
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Petrogenesis of the peralkaline granite (and associated syenite) dykes of the Straumsvola Complex, Western Dronning Maud Land, Antarctica
… of a parental peralkaline magma of trachyte composition.
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Geochemical and isotopic constraints on the source regions of phanerozoic carbonatites and associated alkaline rocks from the Zandkopsdrift complex of Namaqualand, South Africa, and the Marinkas Quellen, and Dicker Willem complexes in Namibia
… at Zandkopsdrift, nepheline syenite and trachyte at Marinkas Quellen, and ijolite and trachyte at Dicker Willem. At both Marinkas Quellen and Dicker Willem, the trachytes appear to be derived primarily from fenitised country rock. The major and trace element characteristics, enrichment in …
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Geology of the Christmas and Rosillos Mountains, Brewster County, Texas
… granite, sodic and non-sodic rhyolite and trachyte, basalt, and gabbro. The Christmas Mountains are an elliptical dome of Devils River limestone probably underlain by a gabbro laccolith which uplifted the limestone about 4,000 feet. The sedimentary formations formerly overlying the Devils …
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The geochemistry and petrogenesis of the Saltpeterkop carbonatite complex near Sutherland, Northern Cape, South Africa
… order of abundance): carbonatite, potassic trachyte, olivine melilitite and ultramafic lamprophyre. This thesis provides the first detailed petrographic and geochemical description of these rocks (e.g., major and trace elements) and attempts to explain several aspects of their petrogenesis. …
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Tertiary and carboniferous magmatism around Lundy Island and the outer Bristol Channel - a geophysical and geochemical perspective
… Lundy Dyke Swarm comprises basalt/dolerite and trachyte to rhyolite intrusions within host Tertiary granite (58.7 ± 1.6 Ma) and Devonian sediments. Outcrops of dykes are confined to coastal exposures on Lundy as they are veneered by peat over most of the island. Dykes present paired magnetic …
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New incision rates on the Colorado River system based on cosmogenic burial dating of terraces : implications for a transient knickpoint at Lees Ferry and differential uplift of the Rocky Mountains
… (e.g. Navajo Mountain, Fremont River and Trachyte Creek) partly result from minimum estimates of age but still may suggest incision rates had increased ca. 500 ka due to knickpoint propagation following slower average incision in the last 1-2 Ma. A new cosmogenic burial isochron date of …
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The evolution of the Baie Verte Lineament, Burlington Peninsula, Newfoundland
… sequence of silicic volcanics, mafic and trachyte lava flows, and mostly conglomeratic sediments. A stratigraphy is defined for the Mic Mac Lake Group. The sequence dips west at moderate angles and, with the significant exception of a narrow strip at the western side, faces west. The Baie …
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The geochemistry and petrogenesis of lavas from the Comores Archipelago, Western Indian Ocean (Volume 2)
… basaltic trachyandesite and trachyandesite to trachyte, and from basanite and nephelinite through phonotephrite to phonolite. Comorean lavas have high incompatible element abundances and display strongly light rare earth element-enriched chondrite-normalised REE patterns. On the basis of their …
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The geochemistry and petrogenesis of lavas from the Comores Archipelago, Western Indian Ocean (Volume 1)
… basaltic trachyandesite and trachyandesite to trachyte, and from basanite and nephelinite through phonotephrite to phonolite. Comorean lavas have high incompatible element abundances and display strongly light rare earth element-enriched chondrite-normalised REE patterns. On the basis of their …
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The Cretaceous to recent history of the southeastern Indian Ocean : the role of mantle plumes examined by geochronology and Sr, Nd, Pb and He isotopic geochemistry
… of the Ocean Drilling Program recovered basalt, trachyte, and garnet-biotite gneiss clasts from a 26 m thick fluvial conglomerate which is intercalated with Kerguelen Plateau basalts. Zircons and monazites obtained from the gneiss clasts yield a range of Proterozoic Pb-Pb dates when examined by …
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Engineering geological characterization of volcanic rocks of ethiopian and sardinian highlands to be used as construction materials
… ignimbrite/rhyolite, tuff and minor trachyte. Thorough literature review has been conducted on volcanic rocks as construction materials and from the compiled information a laboratory testing program was envisaged and conducted on the samples collected from the studied areas. Selection …