Genesis of analcime and nepheline-potassiumfeldspar-kalsilite intergrowths: a review (2009)
- Authors:
- USP affiliated authors: GOMES, CELSO DE BARROS - IGC ; RUBERTI, EXCELSO - IGC
- Unidade: IGC
- Subjects: ROCHAS MAGMÁTICAS; PETROLOGIA; GEOQUÍMICA
- Language: Inglês
- Abstract: The controversial origin of potassic rock suites (lava flows and dykes) containing analcime and pseudoleucite, which may occur as gi- ant trapezohedra {211}, has remained for several decades a hot topic in petrological research. This controversy still persists and as a contribution to the genesis of these minerals, we here examine a few interesting occurrences of analcime and pseudoleucite exhibit- ing complex intergrowths of alkali-feldspar-analcime-leucite or nepheline-alkali-feldspars in potassic rocks of Iran (North-Eastern Azerbaijan volcanics), Brazil (Poços de Caldas and Banhadão) and Paraguay. Our study supports the view that the phenomenon of ion exchange involving Na+ and H2O, and K+ diffusion in presence of Na-rich water results in the conversion of leucite to analcime. Under hydrous conditions alteration or interaction takes place between pre-existing Na-rich phases, such as, nepheline, feldspar and glass. Also, at lower temperatures below the solidus, and at high CO2 activity, sodium-rich leucite breaks down to a complex inter- growths of orthoclase and nepheline resulting in the development of pseudoleucite, which may retain the original trapezohedral form of leucite. We describe several typologies corresponding to the processes leading to the formation of analcime and complex inter- growths in pseudoleucites occurring in rare potassic suites found in widely separated localities. The study of various topologies cor- roborates the conclusions drawn from experimental petrology, which indicates that the replacement of leucite by analcime is a solid- state reaction involving cation exchange by volume diffusion.
- Imprenta:
- Source:
- Título: Acta vulcanologica
- ISSN: 1121-9114
- Volume/Número/Paginação/Ano: v. 21, n. 1-2. p. 81-90
-
ABNT
COMIN-CHIARAMONTI, P. et al. Genesis of analcime and nepheline-potassiumfeldspar-kalsilite intergrowths: a review. Acta vulcanologica, v. 21, n. 1-2. p. 81-90, 2009Tradução . . Disponível em: https://www.researchgate.net/publication/255708575_Genesis_of_analcime_and_nepheline-potassium_feldspar-kalsilite_intergrowths_a_review. Acesso em: 03 mar. 2026. -
APA
Comin-Chiaramonti, P., Cundari, A., Ruberti, E., De Min, A., Gittins, J., Gomes, C. B., & Gwalani, L. (2009). Genesis of analcime and nepheline-potassiumfeldspar-kalsilite intergrowths: a review. Acta vulcanologica, 21( 1-2. p. 81-90). Recuperado de https://www.researchgate.net/publication/255708575_Genesis_of_analcime_and_nepheline-potassium_feldspar-kalsilite_intergrowths_a_review -
NLM
Comin-Chiaramonti P, Cundari A, Ruberti E, De Min A, Gittins J, Gomes CB, Gwalani L. Genesis of analcime and nepheline-potassiumfeldspar-kalsilite intergrowths: a review [Internet]. Acta vulcanologica. 2009 ; 21( 1-2. p. 81-90):[citado 2026 mar. 03 ] Available from: https://www.researchgate.net/publication/255708575_Genesis_of_analcime_and_nepheline-potassium_feldspar-kalsilite_intergrowths_a_review -
Vancouver
Comin-Chiaramonti P, Cundari A, Ruberti E, De Min A, Gittins J, Gomes CB, Gwalani L. Genesis of analcime and nepheline-potassiumfeldspar-kalsilite intergrowths: a review [Internet]. Acta vulcanologica. 2009 ; 21( 1-2. p. 81-90):[citado 2026 mar. 03 ] Available from: https://www.researchgate.net/publication/255708575_Genesis_of_analcime_and_nepheline-potassium_feldspar-kalsilite_intergrowths_a_review - Magmatismo alcalino-carbonatítico da plataforma sul-americana: uma revisão
- Petrological, geochemical and Sr-Nd isotopic features of alkaline rocks from the Arraial do Cabo Frio peninsula (southeastern Brazil)
- The alkaline and alkaline-carbonatite magmatism from Southern Brazil
- Descrição das ocorrências I
- Associações petrográficas
- Características dos principais tipos petrográficos
- Jacupiranga alkaline complex
- Aspectos geoquímicos das rochas alcalinas do Maciço do Banhadão, PR
- Petrological and geochemical studies of alkaline rocks from continental Brazil. 6. The phonolite-tephrite suite from Fortaleza, State of Ceará
- Petrological and geochemical studies of alkaline rocks from continental Brazil: 3. Fenitization of jacupirangite by carbonatite magmas in the Jacupiranga Complex, SP
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