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Geologia e geocronologia U-Pb SHRIMP do ortognaisse Caiongo – domínio São José Campestre, província Borborema, nordeste do Brasil
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Advisor(s)
Abstract(s)
O Ortognaisse Caiongo faz parte do contexto geológico da
porção norte da Província Borborema, mais precisamente no Domínio São
José do Campestre. Trata-se de um corpo de formato sigmoidal, alojado
entre as Zonas de Cisalhamento Picuí – João Câmara e Lajes-Pintadas com
cerca de 44 km2 de área aflorante. Suas fácies possuem textura facoidal, e
composição variando entre sienogranítica a álcali-feldspato granítica. São
rochas leucocráticas a mesocráticas, com feldspatos potássicos que chegam
a 5 cm. Geoquimicamente essas rochas apresentam composição
metaluminosa e shoshonítica, e concentração de elementos traços
semelhantes aos encontrados em granitoides do tipo A. Possui idade de
cristalização do protólito paleoproterozoico (2,223 ± 32 Ma). O εNd (t) de
-0,25, além de sua idade TDM de 2,430 Ma, sugere alguma contaminação
crustal na formação do protólito desta rocha.
The Ortognaisse Caiongo is part of the geological context of the northern part of the Borborema Province, more precisely in the São José do Campestre Domain. It is a sigmoidal shape body, located between the Shear Zones Picuí – João Câmara and Lajes-Pintada, with about 44 km2 outcropping area. Its shows facoidal texture and compositions between syenogranitic and alkali-feldspar granitic. They are leucocratic to mesocratic rocks, with potassium feldspars reaching 5 cm. Composed of different amounts of microcline, plagioclase, quartz, biotite, hornblende, as essential minerals, and titanite, allanite, ilmenite, epidote, zircon and apatite as accessory minerals. Geochemically, these rocks display a metaluminous and shoshonitic composition, along with a trace elements concentration similar to those found in type A granitoids. They have a crystallization age of 2.223 ± 32 Ma. Its εNd (t) of -0.25, in addition to its TDM age of 2.430 Ma, suggest some crustal contamination on the formation of the protolith.
The Ortognaisse Caiongo is part of the geological context of the northern part of the Borborema Province, more precisely in the São José do Campestre Domain. It is a sigmoidal shape body, located between the Shear Zones Picuí – João Câmara and Lajes-Pintada, with about 44 km2 outcropping area. Its shows facoidal texture and compositions between syenogranitic and alkali-feldspar granitic. They are leucocratic to mesocratic rocks, with potassium feldspars reaching 5 cm. Composed of different amounts of microcline, plagioclase, quartz, biotite, hornblende, as essential minerals, and titanite, allanite, ilmenite, epidote, zircon and apatite as accessory minerals. Geochemically, these rocks display a metaluminous and shoshonitic composition, along with a trace elements concentration similar to those found in type A granitoids. They have a crystallization age of 2.223 ± 32 Ma. Its εNd (t) of -0.25, in addition to its TDM age of 2.430 Ma, suggest some crustal contamination on the formation of the protolith.
Description
Keywords
Ortognaisse Domínio São José do Campestre Paleoproterozoico Orthogneiss São José do Campestre Domain Paleoproterozoic
Citation
Dáttoli et al. 2020, ‘Geologia e geocronologia U-Pb SHRIMP do ortognaisse Caiongo: domínio São José Campestre, província Borborema, nordeste do Brasil’, Comunicações Geológicas, vol. 107, nº 1, pp. 21-29.
Publisher
LNEG - Laboratório Nacional de Energia e Geologia