Agpaitic Alkaline Rocks in Southern Brazilian Platform: A Review
| Autor: | Gaston Eduardo Enrich Rojas, Excelso Ruberti, Rogério Guitarrari Azzone, Vincenza Guarino, Celso B. Gomes |
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| Přispěvatelé: | Gomes, Celso de Barro, Azzone, Rogério Guitarrari, Rojas, Gaston Eduardo Enrich, Guarino, Vincenza, Ruberti, Excelso |
| Rok vydání: | 2021 |
| Předmět: |
geography
Mineral geography.geographical_feature_category alkaline magmatism Early Triassic Geochemistry Eudialyte Geology Massif engineering.material Mineral chemistry Mineralogy Geotechnical Engineering and Engineering Geology Hydrothermal circulation Cretaceous mineral chemistry ROCHAS ÍGNEAS Stage (stratigraphy) engineering Brazilian platform agpaitic rocks QE351-399.2 |
| Zdroj: | Minerals, Vol 11, Iss 934, p 934 (2021) Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP |
| ISSN: | 2075-163X |
| Popis: | General information is presented on ten agpaitic occurrences located in southern Brazil and at the border between Brazil and Paraguay. All the Brazilian agpaitic rocks are Late Cretaceous in age, whereas the Paraguayan ones are older than Early Triassic. The most significant occurrence is Poços de Caldas, the largest alkaline massif in South America. In general, these agpaitic rocks contain mineral assemblages that indicate presence of typical halogen-bearing Na–Ca–HFSE phases, eudialyte-, rinkite- and wöhlerite-group minerals being the most frequent ones. However, these associations are indeed more complex in terms of composition, with accessory phases in some cases consisting of various minerals, including U–Th oxides/silicates, Nb oxides, REE–Sr–Ba bearing carbonates–fluorocarbonates–phosphates–silicates and Zr–Na rich silicates. They usually form late magmatic stage to hydrothermal/deuteric assemblages linked with coarse and fine-grained, mainly silica-undersaturated evolved rocks. Data also indicate significant differences in type, amount and composition of agpaitic minerals in all investigated occurrences. |
| Databáze: | OpenAIRE |
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