Results 131 to 140 of about 2,559 (173)
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The origin of rapakivi texture by sub-isothermal decompression
Precambrian Research, 1999Abstract The rapakivi texture (plagioclase-mantled K-feldspar ovoids, rounded quartz megacrysts and euhedral plagioclase megacrysts in a more fine-grained granitic matrix) has been studied in five Proterozoic (1.64–1.55 Ga) anorogenic rapakivi granite batholiths in the Fennoscandian Shield with emphasis on mineral stability and inherited cores.
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Bacterial weathering of rapakivi granite
Geomicrobiology Journal, 1981Rapakivi granite samples were incubated with Pseudomonas aeruginosa culture solutions in order to elucidate the possible role of bacteria in rapakivi (crumbling stone) disintegration. SEM micrographs showed micromorphological alterations on the incubated rapakivi surface at 21 to 23°C for 20 days.
Antti Vuorinen +3 more
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The Origin of Rapakivi Texture
Journal of Petrology, 199445124
Dempster, TJ, Jenkin, GRT, Rogers, G
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Rapakivi granite, anorthosite and charnockitic plutonism
Nature, 1978THE close association of massive anorthosite and charnockitic granitic rocks is well documented1. Rare earth element (REE) investigations2–4 have indicated that the massive charnockite (mangerite) associated with anorthosite is not comagmatic with it but represents a distinct magma fraction.
F. H. HUBBARD, J. E. WHITLEY
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Mineralogy and Petrology, 1994
This paper deals with the chemical composition of biotites from rapakivi granites. For this purpose, 61 chemical analyses of biotites from composite anorthosite-rapakivi plutons in the Fennoscandian and Ukranian shields were used. Figurative points of the biotite composition were plotted on diagrams designed for biotites byFoster (1960),Winchell (1949)
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This paper deals with the chemical composition of biotites from rapakivi granites. For this purpose, 61 chemical analyses of biotites from composite anorthosite-rapakivi plutons in the Fennoscandian and Ukranian shields were used. Figurative points of the biotite composition were plotted on diagrams designed for biotites byFoster (1960),Winchell (1949)
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2005
Publisher Summary The Paleoproterozoic Svecofennian bedrock of southern Finland formed during a multiphase convergence and collision of lithospheric plates ∼ 1900 Ma ago. The next event to strongly reshape the Finnish bedrock was the emplacement of the rapakivi granites-∼1600 Ma ago, when the Svecofennian mountain chain had already been eroded down ...
O.T. Rämö, I. Haapala
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Publisher Summary The Paleoproterozoic Svecofennian bedrock of southern Finland formed during a multiphase convergence and collision of lithospheric plates ∼ 1900 Ma ago. The next event to strongly reshape the Finnish bedrock was the emplacement of the rapakivi granites-∼1600 Ma ago, when the Svecofennian mountain chain had already been eroded down ...
O.T. Rämö, I. Haapala
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The pressure quench formation of rapakivi texture
Contributions to Mineralogy and Petrology, 1978Chemical and textural data for rapakivi granites are combined with experimentally determined phase equilibria to provide constraints on the growth of mantled feldspars by a pressure quench mechanism. In water saturated melts of granitic composition the mantled texture develops in response to a decrease in pressure of as little as 1–0.5 kbar.
Cherry, Michael E., Trembath, Lowell T.
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The Soca intrusion: a rapakivi granite of Uruguay
Journal of South American Earth Sciences, 1998Abstract The Soca granite, emplaced in the Rio de la Plata Craton, is located 65 km east of Montevideo. It is a homogeneous porphyritic leucogranite, with almost 75 km 2 of exposed area. Petrographically, the Soca granite is characterized by the occurrence of quartz, plagioclase and alkaline feldspar in two generations, ferrous pyroxene, mica ...
P. Oyhantçabal +3 more
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Metallogeny of the Rapakivi granites
Mineralogy and Petrology, 1995Two major types of ore deposits occur with Proterozoic rapakivi granite plutons: (1) greisen-, vein-, und skarn-type Sn(-W-Be-Zn-Cu-Pb) deposits associated with specialized late-stage granites, and (2) Fe oxide-Cu (-U-Au-Ag) deposits.
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