Chapter 45 Glacially influenced sedimentation of the Puga Formation, Cuiabá Group and Jacadigo Group, and associated carbonates of the Araras and Corumbá groups, Paraguay Belt, Brazil
| Autor: | Carlos José Souza de Alvarenga, Alexandre Uhlein, Paulo César Boggiani, Marly Babinski, Roland Trompette, Milene Freitas Figueiredo, Alcides N. Sial, Roberto Ventura Santos, Marcel Auguste Dardenne, Elton Luiz Dantas |
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| Rok vydání: | 2011 |
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| Zdroj: | Geological Society, London, Memoirs. 36:487-497 |
| ISSN: | 2041-4722 0435-4052 |
| Popis: | Discontinuous exposures of diamictite (>1000 km) termed the Puga Formation (Fm.) and interpreted as being related to a late Cryogenian glacial event are known in the Paraguay Belt (Brazilian–Pan-African Orogeny) and part of the Amazon craton and Rio Apa Block. These diamictite units and a mixed assemblage of sandstone, conglomerate and claystone were first named the Jangada Group. Recent interpretations have shown that the diamictite of the Puga Formation passes laterally into metasediments of the Cuiaba Group, interpreted as glacially influenced turbidites. The correlative Jacadigo Group in the southern Paraguay Belt includes a thick succession of banded iron formation (BIF) bearing large boulders that have been interpreted as recording glacially influenced sedimentation. The diamictite of the Puga Fm. is overlain by two different carbonate-bearing successions, the Corumba Group (Cadieus, Cerradinho, Bocaina, Tamengo and Guaicurus formations) in the south and the Araras Group (Mirassol d9Oeste, Guia, Nobres formations) in the north. Evidence of glaciation in the Puga Fm. consists of striated and faceted pebbles and blocks, and dropstones in the turbidites. Sedimentary and geochemical data from the associated carbonate reinforce the interpretation of a glacial origin. C, O and Sr isotope data from the northern Paraguay Belt are consistent with the proposed late Cryogenian age for the Puga Fm. sedimentation. |
| Databáze: | OpenAIRE |
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