Results 141 to 150 of about 2,536 (164)

Rapakivi granites from Brazil and adjacent areas

Precambrian Research, 1999
Abstract A review of the rapakivi magmatism in Brazil and adjacent areas demonstrates that the dominantly felsic anorogenic complexes of the Amazonian craton can be considered as rapakivi suites. They are found in almost all provinces of the craton and are concentrated in the timespan covering the end of the Palaeoproterozoic until the beginning of ...
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Petrology of rapakivi granites in Salmi massif

International Geology Review, 1968
Crystallization of rapakivi is accompanied by a progressive decrease in the alkali content of the high-temperature granitic magma and by the concurrent increase in its iron content, during the crystallization of potassium feldspar which is followed by the crystallization of biotite.
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Rapakivi Granite of Ezhimala Complex and its Significance

Journal Geological Society of India, 1982
Abstract The field characters, chemistry and the spatial association of the 678 m.y. old Rapakivi granite with gabbros and anorthosites suggest that these litho-units have developed through bimodal magmatic processes whereby heat derived from basic magma parental to the anorthositic rocks caused partial melting at or near the base of the
M. M. Nair, K. T. Vidyadharan
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Granitoids of rapakivi granite-anorthosite and related associations

Precambrian Research, 1991
Abstract Mid-Proterozoic anorthosite-mangerite-charnockite-rapakivi granite (AMCG) magmatic suites have commonly intruded Proterozoic orogenic belts within 100 Ma or less to as much as 600 Ma after cessation of calc-alkalic crustal generation processes. High FeO (FeO+MgO) , high Na2O+K2O, low Al2O3, and reduced redox condition of the granitoids
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Petrogenesis of the Proterozoic rapakivi granites of Finland

1990
The rapakivi granites (1.7 to 1.55 Ga) of southern Finland occur as epizonal batholiths (e.g., the Wiborg, Åland or Ahvenanmaa, Vehmaa, and Laitila batholiths) and stocks cutting the medium- to high-grade metamorphic Svecofennian (1.9 to 1.8 Ga) crust.
Ilmari Haapala, O. Tapani Rämö
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Rapakivi texture from the O’Leary Porphyry, Arizona (U.S.A.)

Bulletin Volcanologique, 1980
The rhyodactic O’Leary Porphyry which forms the Pleistocene (0.233±0.37 m.y.) volcanic domes of O’Leary Peak and Darton Dome in the San Francisco Volcanic Field (northern Arizona, U.S.A.) contains sanidine phenocrysts with oligoclase mantles (rapakivi texture).
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Rapakivi granite problems: plagioclase mantles and ovoid megacrysts

Australian Journal of Earth Sciences, 2016
ABSTRACTMantling of alkali feldspar megacrysts by oligoclase (‘rapakivi texture’) generally can be interpreted as the result of magma mixing, although decompression is a viable interpretation, especially for high-level intrusions. Coexistence of mantled and unmantled crystals can be explained by transfer of mantled crystals (‘antecrysts’) from a mixed (
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Geology, Petrography and Petrology ofthe Rapakivi Granites; The Rapakivi Granites of Finland

İri alkali feldispatm plajiyoklas tarafından çevrelenmesiyle oluşan dokuyu gösteren granitler "Rapakivi Granitleri" olarak adlandırılmaktadır. Çoğunlukla Proterozoyik 1.8-1.0 milyar yıl yaşlı olan rapakivi granitleri, Ukrayna, Baltık ülkeleri, güney Grönland, orta-kıtasal ve batı ABD, Venezüella, Brezilya, Bostwana ve diğer birçok ...
ARSLAN, Mehmet, ASLAN, Zafer
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The origin of rapakivi texture by sub-isothermal decompression

Precambrian Research, 1999
Abstract 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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Rapakivi granites in the geological history of the earth. Part 1, magmatic associations with rapakivi granites: Age, geochemistry, and tectonic setting

Stratigraphy and Geological Correlation, 2009
Rapakivi granites characteristic practically of all old platforms are greatly variable in age and irregularly distributed over the globe. Four types of magmatic associations, which include rapakivi granites, are represented by anorthosite-mangerite-charnockite-rapakivi granite, anorthosite-mangerite-rapakivi-peralkaline granite, gabbro-rapakivi granite-
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