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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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The Problems of the Rapakivi Granites
The Journal of Geology, 1938The rapakivi granites of Fennoscandia, characterized by Johannsen as "abnormal," include coarse-grained rocks having a peculiar ovoidal texture, controlled by the form of their potassium feldspars, which formerly served to define the whole group. When, however, it was realized that associated with the ovoidal varieties there are related granites having
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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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Petrology of rapakivi granites in Salmi massif
International Geology Review, 1968Crystallization 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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Geology and age of the Parguaza rapakivi granite, Venezuela
Geological Society of America Bulletin, 1978The 1,550-m.y.-old Paraguaza granite of the northwestern Guayana Shield in Venezuela represents one of the larger, apparently anorogenic rapakivi intrusive rocks of the world. The massive rapakivi granite intrudes foliated granitic rocks and associated volcanic rocks of trans-Amazonian age in a structural setting transcurrent to the general northeast ...
HENRI E. GAUDETTE +3 more
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Petrogenesis of the Proterozoic rapakivi granites of Finland
1990The 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 Granite of Ezhimala Complex and its Significance
Journal Geological Society of India, 1982Abstract 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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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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Rapakivi texture: An indication of the crystallization of hydrosilicates, II
Earth-Science Reviews, 1985Rapakivi granites have puzzled all who have seriously studied them. Typical rapakivi texture is a mixture of variously mantled, non-mantled or partly mantled, concentrically zoned, plastically distorted, fragmented, reaggregated, large and small ovoids.
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