Gerson Fauth

Ostracodes from the Upper Cretaceous deposits of the Potiguar Basin, northeastern Brazil: taxonomy, paleoecology and paleobiogeography. Part 2: Santonian-Campanian

Sixty-four Ostracoda taxa were recorded from the Santonian–Campanian of Potiguar Basin, northeastern Brazil. The following new species were described: Triebelina anterotuberculata, Triebelina obliquocostata, Cophinia ovalis, Fossocytheridea potiguarensis, Ovocytheridea anterocompressa, Ovocytheridea triangularis, Perissocytheridea jandairensis, Semicytherura musacchioi and Protocosta babinoti. The faunal association indicates predominantly shallow marine environments, intercalated with typically mixohaline levels. These species are mostly endemic, although the presence of six species common to West and North Africa shows that migration was still possible by the end of the Cretaceous.

Paleoenvironmental interpretation through the analysis of ostracodes and carbonate microfacies: study of the Jandaíra Formation, Upper Cretaceous, Potiguar Basin

Paleoecological analyses are important tools for the reconstruction of paleoenvironments. This paper had the objective of using analysis of ostracode assemblages and carbonate microfacies of a well (Carbomil) and an outcrop (Quixere) from the Jandaira Formation, Potiguar Basin, in order to verify how they corroborate and complement the other. Two paleoenvironments for Carbomil Well (assemblages 1 and 2, respectively marine and brackish to neritic environments) and one for Quixere Outcrop (assemblage 3, marine environment) were identified through the ostracode assemblage analysis. Thin section analysis allowed the identification of two different facies for Carbomil Well, i.e. bioclastic packstones to wackstones, a marine brackish or restricted marine system; and bioclastic grainstones to packstones, a normal, shallow marine system. High levels of alteration on the samples prevented an adequate analysis of Quixere Outcrop; however, it seems to point towards a low-energy environment. Overall, information provided by the thin sections corroborate and complement data of the ostracode assemblages, which allowed a higher degree of certainty for the paleoenvironmental analysis.

Paleolimnological inferences based on Oligocene ostracods (Crustacea: Ostracoda) from Tremembé Formation, Southeast Brazil

Non-marine Oligocene ostracods from Tremembé Formation (Taubaté Basin, Southeast Brazil) are studied for the first time. The study reveals rich assemblages which are probably composed of many new taxa, two of which are described here. The sixteen ostracod species registered are classified in the generaCypretta Vávra, Strandesia Stuhlmann,Potamocypris Brady, Heterocypris Claus,Eucypris Vávra, Herpetocypris Brady and Norman, Cytheridella Daday and LimnocythereBrady. Two new species of the latter are herein proposed: L. mandubi sp. nov. and L. katu sp. nov. The succession of ostracod assemblages along the studied core changes conspicuously in composition, abundance and preservation, and are characterized by the following associations: Herpetocypris-Cytheridella (lower), Limnocythere-Cypretta (middle) andPotamocypris-Heterocypris (upper). It is assumed that these associations represent different ecological phases of the paleolake Taubaté which is in accordance to previous stratigraphic and paleontological studies in the basin. The results from this pioneering taxonomic and paleoecological study on ostracods from Tremembé Formation reinforce the potential of these fossils for paleolimnological researches in Brazilian Cenozoic deposits.

Late Maastrichtian Radiolaria from ODP Leg 165 – Site 999B, Colombian Basin

ABSTRACT This work presents a taxonomic study on the Late Maastrichtian radiolarian fauna from ODP Leg 165, Hole 999B, Colombian Basin. The studied fauna is composed by 24 species, being the family Archaeodictyomitridae Pessagno, 1976 the most abundant and diverse. Original opaline skeletons are replaced by calcium carbonate and precise identifications are possible only for those specimens with sturdy skeletons, what strongly suggests a preservational bias. The studied radiolarian fauna was attributed to the Amphipyndax tylotus zone, due to the occurrence of that species. Besides, the fauna described herein presents a low to intermediate latitude paleobiogeographic affinity and falls within the designation of a typical lower bathyal to abyssal one. Finally, the data presented herein are compared to those reported from the closely related ODP Hole 1001B.

The Nodoconchiinae, a new subfamily of Cytheridae (Crustacea, Ostracoda)

The new subfamily Nodoconchiinae of the Cytheridae Baird is erected to accommodate three genera: Austrocythere Hartmann, 1989a, Nodoconcha Hartmann, 1989a and Ectonodoconcha gen. nov.. Austrocythere seems to be known only from the type species A. reticulotuberculata Hartmann, from its type locality in the Recent Antarctic and from the Antarctic Oligocene. Nodoconcha, however, apart from its original record by Hartmann from the Antarctic as Nodoconcha minuta, has also been encountered in the Oligocene of the Antarctic. In the present study, we have identified seven species of Nodoconcha from the Maastrichtian and Danian of the Neuquén Basin, together with a new genus from the Danian, Ectonodoconcha lepidotus gen. et sp. nov.. The new species of Nodoconcha are N. polytorosa sp. nov., N. sanniosis sp. nov. and N. upsilon sp. nov., and Nodoconcha? sp. that is the possible ancestor of the entire group. Previously described species now placed in the genus are: N. paleocenica (Bertels, 1973), N. jaguelensis (Bertels, 1974) and Nodoconcha sp. (Bertels, 1974). The Nodoconcha species are divided into the Minuta and Upsilon groups.

Welcome to Porto Alegre

Brazil is a country of continental proportions, with enormous geological wealth and potential for new discoveries based on innovative research techniques. There are demands for the increase of knowledge on country’s geology. The 48 th Brazilian Congress of Geology (48 th BCG) will play an important role in bringing this knowledge together from academia, industry, professionals and society through courses, talks and discussions.