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Showing 1 to 20 of 52 for “"granitoids"”.
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Geochemical characterisation of Archaean granitoids in eastern Finland
The oldest rocks in Finland are the Archaean grey gneisses of eastern and northern Finland. The Archaean of the Karelian craton spans about 1000 Ma of crustal growth and evolution and forms the core of the Fennoscandian shield. The Karelian province is a complex patchwork of different rock types. …
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Petrology and geochemistry of the granitoids of the Halfway House Dome
… suite”) and gneisses and calc-alkaline K-rich granitoids. The latter is often referred to as granodioritic-granitic-monzogranitic (GGM). Archaean TTG associations are the main components of the Archaean continental crust generated between 4000Ma and 2500Ma whereas the calc-alkaline GGM or high …
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Petrology of early Proterozoic granitoids in the Halls Creek mobile zone, northern Australia
Errata pasted onto front end paper.
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Association of S-type and I-type granitoids in the Neoproterozoic Cameroon orogenic belt, Bafoussam area, West Cameroon : geology, geochemistry and petrogenesis
… surface of ~1000 km2 and dominantly consists of granitoids which intruded wall-rocks of gneiss and migmatite during the Pan-African orogeny. The Bafoussam granitoid emplacement was influenced by the N 30 °E strike-slip shear zone in the prolongation of the Cameroon Volcanic Line, but also by the …
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Granite petrogenesis and crustal evolution studies in the Damara Pan-African orogenic belt, Namibia
Major and trace element data for Damara granitoids distinguish three geochemically distinct granitoid groups, - crustal-melt granitoids, calc-alkaline granitoids and within-plate granitoids. The overwhelming majority of the Oamara granitoids are peraluminous crustal-melt leucogranites which have …
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Petrogenetic and Geochemical characterization of the Spinghar Crystalline Complex in North-Western Pakistan
… and geochemical investigation from the granitoids reveal their calc-alkaline, peraluminous (A/CNK > 1) and S-type character. The high precision U-Pb zircon mean ages of 2349 ± 7.3 Ma for GG and 1831 ± 19 Ma for LG show their emplacement in Early Proterozoic. These granitoids show …
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The evolution of the Archaean continental crust of Northern Zimbabwe
… crust at 2,875 ± 3 Ma and later intrusions of granitoids at 2/800 ± 20 Ma, and2,720 ± 6 Ma (Pb-Pb zircon).<br></br><br></br>Chemically, the early crust was dominated by sodic, Tonalite Trondhjemite-Granodiorite granitoids, whose formation may be modelled by the partial melting of metabasalts …
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The geochemistry of the Atlanta Lobe of the Idaho Batholith in the western United States, Cordillera
… studies of the Late Cretaceous and Tertiary granitoids of the Atlanta lobe of the Idaho batholith in the western United States cordillera have led to new. insights on the nature of the lower crust and have placed constraints on granitoid magma genesis during a transition from a compressional …
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The geologic and tectonic evolution of the Pan-African/Mozambique Belt in East Africa
… Major and trace element data for granitoids from W Ethiopia, S Ethiopia- NE Kenya and central Kenya indicate three geochemically distinct granitoid groups: volcanic are granitoids, crustal melt granitoids and within-plate granitoids. Calc-alkaline rocks predominate in W Ethiopia, …
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Pan-African magmatism and regional tectonics of South Brazil
… Pelotas Batholith is almost entirely composed of granitoids of Pan-African age (600- 4S0m.y.). Both D2 and D3 are recognized in the batholith. A two fold subdivision based on geochemical and field criteria distinguishes the following categories of granitoid; foliated granitoids and unfoliated …
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New Insight Into the Thermal-Tectonic History of the Southern Antarctic Peninsula: (U-Th-Sm)/He and Fission-Track Thermochronologic Results From Northwest Palmer Land and Alexander Island
… analyses of apatite and zircon from arc granitoids of northwest Palmer Land and fore-arc rocks of the LeMay and Fossil Bluff Groups of Alexander Island. These data were modeled via Monte Carlo simulations to generate time-temperature pathways. Thermal models generated for arc granitoids …
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The Construction of a Plutonic Complex in a Continental Arc Setting: The Skookum Butte Stock, Western Montana
… The SBS as well as other Cordilleran Interior granitoids are distinct in mineralogy and geochemistry from granitoids generated in typical subduction-zone settings and these differences indicate a significant amount of crustal contamination. The SBS is lithologically and geochemically similar to …
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The Construction of a Plutonic Complex in a Continental Arc Setting: The Skookum Butte Stock, Western Montana
… The SBS as well as other Cordilleran Interior granitoids are distinct in mineralogy and geochemistry from granitoids generated in typical subduction-zone settings and these differences indicate a significant amount of crustal contamination. The SBS is lithologically and geochemically similar to …
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Structural Analysis of the Northwest Wind Mountain Quadrangle, New Mexico: Proterozoic Shearing to Cenozoic Brittle Faulting in the Burro Mountains
… Ga intrusion of Granite and Rhyolite Province granitoids; 3) significant uplift during the formation of the Ancestral Rockies (~300 Ma) and the Rocky Mountains (~70-50 Ma); and 4) inversion tectonics with reactivation of compressional faults as normal and strike-slip faults during extension …
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Mesozoic alkaline volcanism and mantle evolution of the southwestern São Francisco craton, Brazil
… from the area. Granitic gneiss and juvenile granitoids associated with the greenstones in the Congonhas area give a Transamazonian 2128 Ma Rb-Sr age, which is in agreement with a published 2124 Ma zircon age. Funher west, syntectonic granitoids and metabasalts from the Araxa Group define a …
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Geodynamic evolution and petrogenesis of the neoarchaean Francistown granite-greenstone complex in NE Botswana, SW margin of the Zimbabwe craton
… a suite of geochemically diverse Neoarchaean granitoids and mafic dominated-supracrustal assemblages. All the supracrustal rocks and mafic intrusions have undergone greenschist to lower amphibolite facies metamorphism, but most mafic intrusions have preserved original igneous textures. The …
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MULTISCALE GEOCHEMICAL STUDY OF THE CORNO ALTO COMPLEX (ADAMELLO BATHOLITH)
… The nature and composition of crustal granitoids significantly changed at the Archean-Proterozoic boundary highlighting major changes in the mechanisms of continental crust formation/differentiation throughout the Earth’s history. In particular, the transition from the typical Archean …
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A reconnaissance study of the metamorphic petrology and volcanic geochemistry of a portion of the Island Lake greenstone belt, Manitoba /
… of the belt and along its margins with adjacent granitoids. Most of the belt is within the greenschist metamorphic f acies with amphibolite facies occurring in certain areas near t he margins. A post-tectonic, low pressure thermal event may be responsible for the development of a unit of …
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Structural studies in a Proterozoic gneiss complex and adjacent cover rocks, west Needle Mountains, Colorado
… and metaplutonic gneisses and ca. 1690 Ma granitoids that comprise the basement to the siliciclastic Uncompahgre Group. The mafic and felsic gneisses underwent synkinematic metamorphism and two phases of isoclinal folding and foliation development during D<sub>B</sub>, prior to emplacement …
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Kinematics and timing of the Pinto shear zone, New York Mountains, northeastern Mojave Desert, California
… structurally upwards from undeformed footwall granitoids beneath the shear zone to protomylonite, mylonite, and ultramylonite near its top. Microstructural studies of mylonite and ultramylonite indicate that deformation occurred over a broad range of decreasing temperatures, from lower …
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