Full text
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| Author(s): |
Juliana Machado David
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Geociências (IG/BT) |
| Defense date: | 2014-10-09 |
| Examining board members: |
Rosemarie Rohn Davies;
Renato Pirani Ghilardi;
Carla Klein
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| Advisor: | Marcello Guimarães Simões |
| Abstract | |
During the Late Paleozoic, large areas of the western Gondwana (Paraná Basin, South America, Karoo and Huab basins, South Africa and Namibia) were covered by a huge epeiric sea. In the Early-Middle Permian, this large inland sea was either isolated or had a restricted connection to the Panthalassa ocean. Benthic marine faunas that thrived in this sea were mainly dominated by shallow burrowing bivalves, and evolved under conditions ofextreme geographic isolation. Rocks of the Permian Passa Dois Group, Brazil, and coeval successions in Uruguay, Paraguay, and Argentina encompass the best records of this endemic fauna. Although this fauna has received renewed attention in the last decade, the true evolutionaryhistory of these unique invertebrates is still obscure because of the incomplete and biased information on its taxonomy and systematic. Indeed, most of the studies dealing with the systematics ofthe Permian Passa Dois Group bivalves have focused on the faunas preserved in rocks of the Teresina and Corumbataí formations. Also, the first record of the Permian Paranean bivalves outside the South America, made by M.R. Cooper and B. Kensley in the early 80\'s, was still questionable. In this context, the present research investigated three distinct bivalve faunas in orderto add new and relevant data to our understandings of the evolution of the Permian Passa Dois Group bivalve fauna: (a) the Permian bivalve fauna of the Waterford Formation, Karoo Basin, South Africa; (b) the Permian bivalve fauna of the km 44.6, PR-239 road, basal portion ofthe Serrinha Member, Rio do Rasto Formation, Paraná Basin, Brazil; (c) the Permian bivalve faunaof the Tiaraju region, Teresina Formation, Paraná Basin, Brazil. According to our results, theKaroo bivalve fauna cannot be confidently assigned to any known South American genera or species. The poorly diversified South African assemblage seems to be a regional variant of that of the Paraná Basin, also represented by their own endemic taxa (at least three distinct genera). Hence, the biocorrelation of the South African assemblage with those of the Permian bivalve biozones of the Passa Dois Group, Brazil, cannot be securely constrained. The bivalve assemblage of thebasal portion of the Serrinha Member, Rio do Rasto Formation, includes the presence of the species Terraia curvata, Terraia bipleura, Asterlopsis prosoclina, Beurlenella elongatella, Leinzia curtaand Cowperesia emerita. This stratigraphic range records the new Terraia curvataBiozone, lying between the Pinzonella neotropicaand Leinzia similisbiozones. Additionally, this bivalve fauna could probably record a faunal turnover in the bivalve geological history of the Passa Dois Group, Paraná Basin. The systematic revision of Tiaraju fauna revealed the presence of Terraia falconeri, Terraia altissima, Holdhausiella elongata andCowperesia emerita.The position of this bivalve assemblage in the biostratigraphic scheme of the Passa Dois Group bivalve biozones is still in dispute, since our results indicate the presence of bivalve species that are not commonly found in the same biozone. Additionally, the Tiaraju fauna add evidences that during certain times ofthe geological history of the Paraná Basin, the bivalve species were not regionally confined to areas of that huge epeiric sea. Indeed,both the Tiaraju fauna and the assemblage of the basal portion of Serrinha Member indicate a biocorrelation with deposits of the Permian Gai-As Formation, in the Huab area, Namibia, providing an age no younger than the mid-Permian (Wordian-Captianian) to these sedimentary deposits of the Paraná Basin. (AU) | |
| FAPESP's process: | 11/01975-0 - Systematics, paleoecology and bioestratigraphy of the Permian bivalves of the Rio do Rasto (Paraná Basin, Brazil) and Waterford (Karoo basin, South Africa) formations |
| Grantee: | Juliana Machado David |
| Support Opportunities: | Scholarships in Brazil - Doctorate |