Biostratigraphy of Liminic Ostracoda (Crustacea) from the Quiricó Formation, Lower Cretaceous of the São Francisco Basin, Minas Gerais State, Brazil: An approach on paleozoogeographic evolution of Gondwana

Abstract

The present study is the first biostratigraphic framework based on limnic ostracods for the Quiricó Formation, São Francisco Basin, Brazil. Three sections located at Minas Gerais State were approached: 1. Stratotype section of the Quiricó Formation, Presidente Olegário County; 2. Hypostratotype section of the Tereza Farm, João Pinheiro County; and 3. São Bento Farm section, Carmo do Paranaíba County. After ostracod taxonomic analysis and integration with previous studies, six biostratigraphic units are described, one superzone and five zones. From the lower to the upper part of the Quiricó Formation, zones are: Zone Brasacypris ovum, OSF-0; Zone Timiriasevia sanfranciscanensis, OSF-1.1; Zone Cypridea hystrix, OSF-1.2; Zone Alicenula longiformis, OSF-1.3; and Zone Harbinia spp., OSF-1.4. Superzone Penthesilenula pintoi, OSF-1, comprises zones Timiriasevia sanfranciscanensis, Cypridea hystrix, Alicenula longiformis and Harbinia spp, and is attributed to the Berriasian–Albian? interval. The Brasacypris ovum Zone is attributed to the Berriasian; the Timiriasevia sanfranciscanensis Zone is attributed to the Berriasian; the Cypridea hystrix Zone is attributed to the Valanginian–Hauterivian interval; the Alicenula longiformis Zone is attributed to the Barremian; and the Harbinia spp. Zone is attributed to the Aptian. A paleozoogeographic analysis showed faunal similarities with several sedimentary basins in Brazil, Argentina, Gabon, Gamba, Congo and Cabinda during the late assemblage of Gondwana previous to the complete breakup of the supercontinent.