Taxonomia dos ostracodes Quaternários do talude continental da Bacia de Santos a partir do testemunho SAN 212

Abstract

Studies on Quaternary ostracofauna of the Brazilian continental slope have increased in recent years. The material studied comes from deep-water marine Quaternary deposits, which are part of the lithostratigraphic context of the Marambaia Formation. The objective of this study is to verify the distribution of ostracofauna in the region of the continental slope of the Santos Basin, based on taxonomic analysis. 36 samples were analyzed from 1 (one) core designated SAN 212, which consists of marl, sandy mud and limestone. The composition corresponds to 1683 ostracodes, which allowed the recognition of 9 (nine) families and 21 species represented by Krithidae (Krithe coimbrai, K. dolichodeira, K. trinidadensis, K. producta, K. morkhoveni and K. reversa), Trachyleberididae (Trachyleberis aorata, Philoneptunus provocator, Apatihowella melobesioides, Marwickcythereis ericea and Ambocythere circumporus), Macrocyprididae (Macrocypris similis and Macropyxis adrecta), Bythocyprididae (Bythocypris kyamos and Bythocypris sp.), Bairdiidae (Bairdoppilata ex gr. hirsuta), Cytheruridae (Cytheropteron iornatum), Paracyprididae (Phlyctenophora zealandica and Paracypris sp.), Pontocyprididae (Australoecia atlantica) and Thaerocytheridae (Poseidonamicus pintoi). Among these, the genus Krithe showed greater diversity. The species K. trinidadensis and K. dolichodeira are more abundant, besides these, another species with expressive abundance was Trachyleberis aorata. The well studied is similar in distribution to wells SAN 23 and SAN 65, studied by other authors. From the high occurrence of K. trinidadensis, believed that it is a reflection of the disposition more external to the coastline. All taxa are typical deep-water inhabitants. The presence of Poseidonamicus pintoi and Bythocypris confirms the restriction to paleobathymetry normally below 1000 m depth on the Brazilian margin. There is a slight control in the distribution of ostracods in relation to lithology, with sandy muds being more fruitful for ostracod associations.