Cretaceous dinoflagellate provincialism in Brazilian marginal basins

• Published in: Cretaceous research Vol. 21; no. 2-3; pp. 351 - 366
• Main Authors: Arai, Mitsuru, Botelho Neto, José, Lana, Cecı́lia Cunha, Pedrão, Elizabete
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-04-2000
• Subjects: Brazil; Cretaceous; dinoflagellates; palynology; palynology; Brazil; Cretaceous; dinoflagellates
• ISSN: 0195-6671; 1095-998X
• DOI: 10.1006/cres.2000.0211

Aptian to Maastrichtian dinoflagellate assemblages from northern and northeastern Brazilian basins define an Equatorial Atlantic Province, indicative of the Tethyan Realm. This contrasts with coeval assemblages from southern and southeastern Brazilian basins, which show Austral affinity and define a Tropical/Subtropical Atlantic Province. In the northeastern basins (São Luı́s, Potiguar, Araripe and Ceará) provincialism is marked by theSubtilisphaera Ecozone, which straddles the Aptian–Albian boundary. Diverse Albian dinoflagellate assemblages containing Gordiacysta coronata and Walvisia woodii, both previously reported only from South Atlantic basins, occur in southern and southeastern Brazilian basins (Pelotas, Santos and Campos basins). In northern and northeastern basins (offshore Pará-Maranhao, Piauı́, Ceará and Potiguar) there are no rich Albian dinoflagellate assemblages as a consequence of high terrigenous input. In the Cenomanian–Turonian of southern and southeastern Brazilian basins dinoflagellate assemblages are relatively poor, their low diversity being ascribed to anoxic oceanic events. However, in northern and northeastern basins assemblages are well represented and contain abundant specimens of the genera Circulodinium,Cyclonephelium and Florentinia. Some Florentinia species, e.g., F. berran and F. khaldunii, are typical of the Tethyan province. By contrast, these same species are absent in southern and southeastern basins. In the Senonian, provincialism is manifested mainly by differences among peridinioid dinoflagellates. Southern and southeastern basins contain Chatangiella, Nelsoniella, and Xenikoon. All three genera are rare in the northern and northeastern basins, which contain more diverse Cerodinium assemblages.