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Showing 1 to 20 of 25 for “"tonalite"”.
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A stable isotope study of the Kaap Valley Tonalite, Barberton Mountain Land, South Africa
The Kaap Valley Tonalite (KVT) was a homogenous hornblende+ biotite tonalite that had been subjected to overail propylitic and potassic alteration. Petrographic studies reveal that carbonate alteration and increased proportions of hydrous minerals occur along the KVT and Barberton greenstone belt …
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The Geology And Geochemistry Of The Archean Flavrian Pluton, Noranda, Quebec
… concentration.;Seawater alteration of diorite, tonalite, and andesite overlying the albite granite caused pervasive albitization, Cu-Zn leaching, a lightening of (delta)('18)O(,wr) to +2.9 (+OR-) 1.5%, and other chemical changes. The albite granite intruded these altered rocks, and was itself …
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Geochemistry of igneous rocks from the southern coast belt plutonic complex, southwestern British Columbia
… rocks, ranging in composition from granite, tonalite, quartz diorite, diorite to gabbro, with an average composition of quartz diorite. Subordinate Permian to Quaternary metamorphic and volcanic rocks make up the remainder of the southern CPC. Nd, Sr, and Pb isotopic data suggest that …
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The geology of the area east of Pofadder with emphasis on shearing associated with the Pofadder lineament, North West Cape
… intrusive rocks include a granodiorite-tonalite suite, diorite, pegmatite and vein quartz. Dolerite is post-tectonic, most likely of Karoo age and occurs as sills and remnant hillocks. Non-diamondiferous kirnberlite pipes occur in the west and their emplacement appears to have been …
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Crystalline bedrock geology of the lower Susquehanna Gorge: Conowingo to Havre de Grace, Maryland
… Mafic Complex) and associated plutons (Basin Run Tonalite). Many olistoliths within the Conowingo Dam Formation could have originated in the Havre de Grace Block. The Havre de Grace Block was metamorphosed and deformed under amphibolite facies conditions during Middle Ordovician to Early Silurian …
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Geologic framework of gravity anomaly sources in the central Piedmont of Virginia
… gm/cc, Columbia Granitoid-2.75 gm/cc (tonalite) and 2.73 gm/cc (pegmatite), Chopawamsic Volcanics- 2.77 gm/cc (felsic units), and 2.79 gm/cc (mafic units}, Catoctin/ Lynchburg-2.815 gm/cc, Maidens Gneiss-2.775 gm/cc, Grenville Basement- 2.71 gm/cc. Gravity and seismic data are …
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Petrogenesis of a migmatite, Penobscot County, Maine: ultrametamorphism or intrusion?
… from 7-88% areally, and in composition from tonalite to alkali granite. Igneous textures in leucosomes argue against a solid-state origin, while biotite and plagioclase analyses indicate that leucosomes were not generated by in situ melting. Compositions of plagioclase (An-content 33-28 in …
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Major element and isotopic studies on the James Run/Port Deposit association, Maryland: tectonic analogues and Taconic deformation
… meta-igneous rocks as a bimodal tholeiite-dacite/tonalite suite with trondhjemitic affinities and indicate that subsolidus alteration during dynamic metamorphism was minor. Comparison of these data with other tectonic environments suggests their generation by partial fusion of amphibolitic …
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Geologic evolution of the Archean Buhwa Greenstone Belt and surrounding granite-gneiss terrane, southcentral Zimbabwe
… consisted of several lithologies including tonalite, mafic-ultramafic volcanic rocks, and granite that underwent intense chemical weathering. Basinal deposits consist dominantly of greenstones, with less abundant chert and ironformation. The cover succession, which was deposited on a stable …
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The evolution of the Archaean continental crust of Northern Zimbabwe
… the early crust was dominated by sodic, Tonalite Trondhjemite-Granodiorite granitoids, whose formation may be modelled by the partial melting of metabasalts with residual hornblende and/or garnet. By contrast, the granitoids formed during the Late Archaean "event" which culminated in the …
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Petrology and geochemistry of the granitoids of the Halfway House Dome
… main rock associations, i.e. greenstone belts, tonalite-trondhjemite-granodiorite (termed “TTG 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 …
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Petrologic Significance of Multiple Magmas in the Quottoon Igneous Complex, NW British Columbia and SE Alaska
… the generation of other portions of the Great Tonalite Sill of southeast Alaska.
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Geochemical investigation of Meso- to Neoarchean (3075–2800 Ma) supracrustal rocks in the Nuuk region, southern west Greenland
… exhibit a tectonic contact with the surrounding tonalite-throndjemite-granodite (TTG) gneisses. Metavolcanic rocks in this belt possess near-flat to slightly enriched LREE patterns and pronounced negative Nb-Ta anomalies indicating a subduction zone geochemical signature. Metasedimentary rocks …
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Temperature-dependent thermal transport properties of major Archean rock types and implications for the thermal evolution of Archean terranes
… (GG) belts and intrusions of high heat-producing tonalite-trondhjemite-granodiorite (TTG), and the burial of TTG rocks below GG rocks is believed to have triggered dome-and-keel formation. The thermal transport properties of these rocks, thermal diffusivity (D), and thermal conductivity (k), are …
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Geology of the Snip Mine, and its relationship to the magmatic and deformational history of the Johnny Mountain area, northwestern British Columbia
… plagioclase porphyritic quartz diorite to tonalite stock, intrudes the greywacke sequence 300-800 metres northeast of the Twin zone. Two successive, intense hydrothermal events are centred on the porphyry and are associated with subeconomic Au and Cu concentrations. These are: (i) early …
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Structural evolution of crystalline lower plate rocks, Central Sacramento Mountains, Southeastern California
… ratios (eg. granodiorite, diorite, tonalite, quartz diorite) do not form foliations as easily as rocks with low strong-to-weak ratios (eg. granite). This results in a diffuse distribution of mylonitic fabrics and many small scale shear zone boundaries. There is no evidence, however, …
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Proterozoic evolution of the Zuni Mountains, New Mexico: Peridotites, granites, rhyolites, shear zones, and a reactivation history through the present
… cumulate or an exotic slice of mantle, 2) tonalite/granodiorite with mafic enclaves, 3) quartz monzonite and rhyolite that represent shallow-level magmatism at ca. 1.65 Ga. The peridotite exists in an elongate lens and several discrete pods that were metamorphosed and hydrothermally altered …
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Geology of the Zacapa Quadrangle and vicinity, Guatemala, Central America
… and associated penetratively deformed diorite, tonalite and granodiorite. Metavolcanic, metavolcaniclastic, and metasedimentary rock includes original basalt, dacitic and rhyodacitic tuff, minor andesite, limestone and pelite. Emplacement of diorite coincided with regional prograde metamorphism …
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The geology and geochemistry of the Omai goldfield, Guyana
… is centred on a high-AI, quartz diorite-tonalite boss (the Omai Stock), where wall-rock alteration is dominated by a hydrothermal sericite-carbonate assemblage. The primary ore package of Au-W-Te-S mineralisation is contained in a series of narrow (1-5cm), quartzcarbonate (ankerite) …
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The geology, petrography, geochemistry and uranium ore mineralogy of the Namibplaas sheeted leucogranites, Damaran orogen, Namibia
… leucogranitic bodies range in composition from tonalite to syenogranite. The Namibplaas leucogranites are peraluminous to metaluminous indicating a highly evolved crustal source most probably the Abbabis basement gneisses. Partial melting of the Abbabis basement gneisses which was induced by M2 …
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