Permian bivalve molluscs from the Gai-As Formation,northern Namibia: systematics,taphonomy and biostratigraphy |
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| Authors: | Juliana M David Marcello G Simões Luiz E Anelli Rosemarie Rohn Frank Holzfoerster |
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| Institution: | 1. Instituto de Geociências e Ciências Exatas , Universidade Estadual Paulista, Programa de Pós-gradua??o em Geologia Regional , 13.506–900, Rio Claro, SP, Brazil juliana_mdavid@yahoo.com.br;3. Instituto de Biociências , Universidade Estadual Paulista, Distrito de Rubi?o Junior , CP 510, 18.610–000, Botucatu, SP, Brazil;4. Instituto de Geociências , Universidade de S?o Paulo, Cidade Universitária , 05.508–080, S?o Paulo, SP, Brazil;5. Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Departamento de Geologia Aplicada , 13.506–900, Rio Claro, SP, Brazil;6. GEO-Zentrum an der KTB , Am Bohrturm 2, 92670, Windischeschenbach, Germany |
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| Abstract: | Fossil bivalves from two horizons in the Gai-As Formation of NW Namibia are tentatively correlated with mid-Permian taxa of the Passa Dois Group of Brazil, supporting the concept that the Paraná Basin extended into Africa. The Namibian fauna includes a new genus and species, Huabiella compressa, which was previously confused with Brazilian taxa. The taphonomy of the bivalve-rich strata indicates deposition under the influence of episodic events, such as storms. The Gai-As Formation directly overlies the mesosaurid-bearing deposits of the Huab Formation, indicating a significant unconformity when compared with the more complete succession of the Passa Dois Group, Paraná Basin, Brazil. The studied bivalve assemblages are no younger than 265±2.5 Ma (mid-Permian), based on U/Pb radiometric dating of zircons from tuffs. |
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| Keywords: | Bivalvia Megadesmidae Permian Huab area Gai-As Formation biostratigraphy Rio do Rasto Formation |
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