The faunal and geochemical approaches in the calcareous microfossils and their applications to the palaeoceanography and palaeoclimatology

Micropalaeontology is an important ally to the palaeoceanography and palaeoclimatology contributing to the study of factors such as sedimentation rates, sea level and hydrological changes (e.g. circulation, temperature, productivity and salinity). This revision article aims to present the main applications of three important groups of calcareous microfossils: nannofossils, foraminifers and ostracodes. Species composition and geochemical approaches on those groups both in Cretaceous and Cenozoic are discussed based on studies published in the last years, referring whenever it possible to examples of studies developed in Brazil

New oligocene cyprididae species (crustacea, ostracoda) from the tremembé formation, Taubaté Basin, Brazil, and their paleolimnological significance

Two new Oligocene ostracod species, Eucypris lobatoi sp. nov. and Potamocypris taubatensis sp. nov., are herein proposed. This is the first fossil record of these genera in Brazil, and the species identified occur in two distinct phases of the Tremembé Paleolake. It is assumed that Eucypris lobatoi sp. nov. has lived in the oldest and more stable phase of the lake, Potamocypris taubatensis sp. nov., in the youngest and more unstable phase. These data support a previous ostracod-based paleolimnological interpretation which sustains a shallowing trend in the paleolake during the final deposition of the Tremembé Formation.Duas novas espécies de ostracodes, Eucypris lobatoi sp. nov. e Potamocypris taubatensis sp. nov., são propostas neste trabalho. Este é o primeiro registro fóssil destes gêneros no Brasil, cujas espécies identificadas ocorrem em duas fases distintas do Paleolago Tremembé. Eucypris lobatoi sp. nov. ocorre durante a fase mais antiga e estável do paleolago, enquanto Potamocypris taubatensis sp. nov., na fase mais recente e instável. Estes dados corroboram uma interpretação paleolimnológica prévia baseada em ostracodes que sustenta uma tendência de raseamento do paleolago durante o final da deposição da Formação Tremembé

Climatically induced changes in late Quaternary bathyal ostracod assemblages of the Camamu Basin, Brazil

Bathybic ostracods (i.e., bathyal and abyssal assemblages) are important indicators of temperature and productivity changes of Cenozoic marine ecosystems. The present work presents the first study on Quaternary ostracods of the Camamu Basin, off the state of Bahia, northeastern Brazilian continental margin. The analysis of 59 samples from the piston-core CMU 14 (14°24’S, 38°49’W; 965 m water depth), revealed rich and abundant assemblages. The 14C accelerator mass spectrometry (AMS) dating indicates that the studied interval covers the last 108 kyr, corresponding to the oxygen stable isotope stages (MIS) 5 to 1. Comparison with data from previous publications allowed discernment of three groups of ostracod species in CMU 14: Pandemic Group of species registered in more than one oceanic basin; Atlantic/Mediterranean Group of species restricted to the Atlantic Ocean and Mediterranean; and Brazilian Group of species restricted to the Brazilian continental margin). Four new species are herein proposed: Cytherella pindoramensis sp. nov., Ambocythere amadoi sp. nov., Pseudobosquetina pucketti sp. nov., and Bythoceratina bonaterrae sp. nov. Ostracod occurrences reveal the influence of glacial/interglacial cycles on assemblages composition. Interglacial stages 5 and 1 in the Camamu Basin are characterized by the association Bythocypris affinis–Cytherella pindoramensis sp. nov.– Cytheropteron perlaria–Bradleya dictyon; glacial stages (i.e., 2 to 4) register decreased diversity, possibly due to lower oceanic productivity

A Permian mixohaline ostracod association of the Teresina Formation, Paraná Basin, Brazil

New ostracod species are described for Middle to Upper Permian (Guadalupian) rocks of the Teresina Formation, Paraná Basin, from two localities in the São Paulo State, southwestern Brazil: Xavante Dam and Pau Preto Quarry. Paranacythere nigripallus gen. nov. and sp. nov., Velatomorpha xavante sp. nov., and Velatomorpha pseudoaltilis sp. nov. are herein described. The association Velatomorpha– Paranacythere is proposed as typical of Permian mixohaline environments of the Teresina Formation, and is the most abundant in the two studied localities. Paranacythere nigripallus gen. nov. and sp. nov. is proposed to accommodate a very abundant species with typically cytheroidean characteristics, and tentatively ascribed to the family Cytheruridae. Some ecological remarks are presented based on ostracod population age structure, biostratinomy and taxonomic composition of assemblages. The diagnosis of Velatomorpha Tibert & Dewey is emended.Novas espécies de ostracodes são propostas para rochas do Permiano Médio a Superior (Guadalupiano) da Formação Teresina, Bacia do Paraná, em duas localidades no Estado de São Paulo, sudeste do Brasil: Represa Xavante e Pedreira Pau Preto. Paranacythere nigripallus gen. nov. e sp. nov., Velatomorpha xavante sp. nov., and Velatomorpha pseudoaltilis sp. nov. são descritas. A associação entre os gêneros Velatomorpha e Paranacythere é interpretada como típica de ambientes mixoalinos da Formação Teresina, e são os ostracodes mais abundantes nas localidades aqui estudadas. Paranacythere nigripallus gen. nov. e sp. nov. é proposto para acomodar uma espécie com características tipicamente cytheroides e tentativamente atribuído à família Cytheruridae. Aspectos ecológicos são discutidos com base na estrutura populacional etária, biostratinomia e composição taxonômica das assembleias. É proposta uma emenda à diagnose de Velatomorpha Tibert & Dewey

Paleoecological characterization of ostracods in beachrocks from the Northern sector of the Rio Grande do Sul Coastal Plain, Brazil

A micropaleontological analysis on 15 beachrock samples from the Northern sector of Rio Grande do Sul Coastal Plain (RSCP), southern Brazil, revealed a relatively diverse and well-preserved ostracod assemblage composed of 16 species, including Cyprideis multidentata Hartmann, Callistocythere nucleoperiscum Whatley et al., Cytheretta punctata Sanguinetti, Caudites ohmerti Coimbra & Ornellas, and Argenticytheretta levipunctata Sanguinetti et al. Eleven ostracod species are left in open nomenclature or tentatively identified. Besides ostracods, some foraminifers, echinoderm spines, and fish remains (teeth) were also recovered; however, the scarcity of specimens or poor preservation precluded identification at species level. Based on the Ostracoda taxonomic composition it is proposed that the beachrocks characterize environmentally condensed assemblages. This preliminary study reveals the importance and potentiality of micropaleontology for understanding the processes involved in the formation of beachrocks.O estudo micropaleontológico de 15 amostras de arenitos de praia provenientes do setor norte da Planície Costeira do Rio Grande do Sul (PCRS), sul do Brasil, revelou uma assembleia relativamente diversa e bem preservada de ostracodes, composta por 16 espécies, incluindo Cyprideis multidentata Hartmann, Callistocythere nucleoperiscum Whatley et al., Cytheretta punctata Sanguinetti, Caudites ohmerti Coimbra & Ornellas e Argenticytheretta levipunctata Sanguinetti et al. Onze espécies são registradas em nomenclatura aberta ou tentativamente identificadas. Além dos ostracodes, foraminíferos, espinhos de equinodermos e vestígios de peixes (dentes) foram também recuperados, contudo, a baixa abundância e/ou preservação impediram a identificação em nível de espécie. A composição taxonômica dos ostracodes indica que estas rochas registram assembleias ecologicamente condensadas. Este estudo preliminar revela a importância e potencialidades da micropaleontologia para a caracterização dos processos envolvidos na formação de arenitos de praia

Les ostracodes des sédiments du Crétacé supérieur du Bassin de Potiguar, NE Brésil : taxonomie, paléoécologie et paléobiogéographie. Première partie : Le Turonien

This paper describes thirteen new species and two new genera of marine and brackish water ostracodes from the Turonian deposits of Potiguar Basin, NE Brazil, among a total of 53 taxa. The new species include Cophinia grekoffi, Fossocytheridea tiberti, Haughtonileberis dinglei, Hemicytherura viviersae, Jandairella obesa (new genus and species), Loxocorniculum? narendrai, Ovocytheridea posteroprojecta, O. reymenti, Perissocytheridea caudata, P. mossoroensis, Potiguarella grosdidieri (new genus and species), P. coimbrai and Procytherura ballentae. The diversity and dominance indexes vary according to the paleoenvironment. Three assemblages were identified: a predominantly mixohaline fauna in the basal part of the section, followed by a diversified shallow marine fauna and, in the upper part, a marine and brackish water ostracode fauna. Most of the recorded species are endemic. Eight species are common to Northwest and North Africa, indicating a faunal link during the Turonian. The study of the Turonian faunas of the Potiguar Basin represents a significant improvement to understand the dynamic evolution of the Brazilian basins and the paleobiogeographical relationship with other regions

Paleoenvironmental significance of benthic foraminifera and ostracoda from the late quaternary of the Ceará basin, brazilian equatorial margin

Benthic foraminifera, ostracods and pteropods are reliable paleoenvironmental indicators in Quaternary deposits. However, in the Ceará Basin, on the Brazilian Equatorial Margin, these microfossils are poorly studied. This paper investigates environmental changes during the Pleistocene–Holocene transition in the Icaraí subbasin based on micropaleontological analysis of the core ANP 1011. Seventy-four taxa of benthic foraminifera, represented predominantly by Globocassidulina, Uvigerina, Pyrgoand Melonis, have been identified. The ostracod assemblages are composed mainly by the families Macrocyprididae, Cytheruridae, Trachyleberididae, Pontocyprididae andKrithidae, of which the genus Krithe wasthe most abundant. The composition of the ostracod assemblages identified in this study area differs somewhat from other regions of the Brazilian Margin. The assemblages of foraminifera and ostracod characterize atypical bathyal paleoenvironment. The occurrence of pteropods and dominance of epifaunal foraminifera taxa, mainly Pyrgo sp. and Miliolinella sp. in the lower portion of the core (Pleistocene), indicates higher phytodetritus input and oxygen concentration. A conspicuous environmental change was observed in the upper portion of the core, which corresponds to the Holocene, where the increase of infaunal foraminifera (e.g., Uvigerina, Globocassidulina and Melonis) suggests reduction in the organic matter input and, probably, increased bacterial density and depletion in dissolved oxygen in the sediment

Variations of richness and abundance of bathyal marine ostracods from the Campos Basin (Brazil) in response to climatic changes of the late Pleistocene

Benthic marine ostracods are important paleoenvironmental indicators due to their sensitivity to ecological parameters, which are particularly useful in palaeoclimatic and paleoceanographic reconstructions during the Quaternary. The preliminary study of ostracods from 61 samples of a piston core collected from 1503m depth on the continental margin of southeastern Brazil (Campos Basin) showed the existence of a rich but irregularly distributed ostracod fauna. The levels of abundance, here named as events, were numbered from 1 to 6 (E1-E6) and calibrated according to the zones of planktonic foraminifera (W, X, Y). These events that distinguish different associations of planktonic foraminifera are considered as indicative of water temperature fluctuations (from cold to hot), and/or as variation of the sediment content (from marl to carbonate mud). These events show a positive correlation with the isotopic signals of δ18O and δ13C. E1 and E5 events are controlled by lithology, E2-E4 by the temperature surface water, and finally, E-6 is subject to both, lithology and climate. In the intervals of greatest marine ostracod abundance, variations in the degree of calcification and evidence of predation were observed. The taxonomic studies have identified 128 species belonging to 40 genera, mostly recorded in glacial stages. Australoecia atlantica Maddocks, Henryhowella melobesioides (Brady), Poseidonamicus pintoi Benson, Argilloecia spp., Krithe spp. and Bythocypris spp. are the most abundant taxa.Simposio VI: Microfósiles del Mesozoico y Cenozoico de América del Sur y Antártida. Nuevas aplicaciones y problemáticas asociadasFacultad de Ciencias Naturales y Muse