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 do periódico: 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: 23 abr. 2024. -
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 2024 abr. 23 ] 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 2024 abr. 23 ] Available from: https://www.researchgate.net/publication/255708575_Genesis_of_analcime_and_nepheline-potassium_feldspar-kalsilite_intergrowths_a_review - Descrição das ocorrências I
- Associações petrográficas
- Carbonatite complexes from Brazil: a review
- A review of the carbonatitic magmatism in the Paraná Angola-Namibia province
- Petrogenesis of the late cretaceous alkaline complex of Morro Sâo João (southeastern Brazil)
- The tholeiitic dyke swarm of the Arraial do Cabo peninsula (SE Brazil): 39 Ar/40 Ar ages, petrogenesis, and regional significance
- Magmatismo alcalino-carbonatítico da plataforma sul-americana: uma revisão
- Petrologia do maciço alcalino de Itatiaia, RJ-MG-SP
- Petrologia e geoquímica de distritos alcalinos brasileiros: uma síntese
- REE-O-C-Nd systematics in carbonatites from Barra do Itapirapuã and Mato Grosso (southern Brazil)
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