The Paraná Basin, the largest basin in South America, received glacially derived sediments during the Late Palaeozoic Ice Age (LPIA) of the Gondwana supercontinent. Despite the importance of this basin for understanding the continental development of the Gondwana glaciation, and the fact that ca. 95% of this basin is not exposed at the surface, few attempts have been made to connect the exposed glacial strata to the subsurface record. In this paper, exposures of glacial cycles in the Upper Itararé Group in Santa Catarina State, southern Brazil, are analyzed, locally correlated and then linked to the three major glacial cycles previously described from subsurface studies along the basin. Together study areas (Doutor Pedrinho and Vidal Ramos) record five, partially comparable shorter glacial subcycles (relative to the major glacial cycles). These series comprise coarse-grained subaqueous outwash deposits, turbidite sand sheets, marine shales, and diamictites, the latter mostly derived from delta slope failure and ensuing resedimentation. In addition to sedimentological and genetic stratigraphic description and analysis, preliminary age determination based on the palynological content is also presented. Besides, a regional correlation of the described succession to the subsurface record is proposed based on well logs and core information. All the palynomorph associations identified from the exposed successions, which represent the upper third part of the Itararé Group, are related to the Subzone Protohaploxypinus goraiensis, base of the Vittatina costabilis Zone. This zone and correlated ones along the Gondwana are considered Early Permian in age. However, a first isotopic age recently obtained for the upper Itararé Group and published elsewhere is considered within a regional stratigraphic framework once it leads to new insights in terms of the LPIA time span recorded in the Paraná Basin.
Bibliographical noteThis work is part of a research project supported by BG Brazil E&P Ltd. entitled “Carboniferous de-Glacial record in the Paraná Basin and its analogue in the Paganzo Basin of Argentina: Impacts on reservoir predictions”. The authors would also like to acknowledge the ANP (Agência Nacional do Petróleo, Gás Natural e Biocombustível) (ANP BG 29) for its support to the project. This project was carried out at the Universidade do Vale do Rio dos Sinos (UNISINOS) in collaboration with the University of Aberdeen, Universidade Federal do Rio Grande do Sul (UFRGS), Universidad Nacional de San Juan (UNSJ), Argentina, and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). The third author would like to acknowledge the long-term support from the Brazilian Research Council (Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq). A special acknowledgment is made to Carla Puigdomenech, Bruno Vaz de Carvalho and Fabiano Rodrigues, who assisted in the field campaigns.
- Itararé Group
- Sequence stratigraphy