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Ammonite-benthic Foraminifera turnovers across the Lower-Middle Jurassic transition in the Lusitanian Basin (Portugal)

Henriques, Maria Helena Paiva; Luisa Canales, Maria
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
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This paper describes and characterises the co-occurrence of ammonite and benthic foraminiferal assemblages across the São Gião outcrop (Central Portugal), a reference section for the Lower-Middle Jurassic boundary in the Lusitanian Basin. The upper Toarcian-lower Aalenian marls and marly-limestones in this section provide a precise and detailed ammonite-based biostratigraphic zonation, with a mixed assemblage of northwest European and Mediterranean faunal elements, associated with benthic foraminifera assemblages with northern hemisphere affinities, both correlatable with the Aalenian GSSP at the Fuentelsaz section (Iberian Cordillera, Spain). A total of 447 well-preserved ammonite specimens and 13.116 foraminifera have been studied; no evidence was detected of any taphonomic processes that could have changed the original assemblages. From a biostratigraphic point of view, the ammonite record has enabled four biostratigraphic units to be recognised (the Mactra and Aalensis subzones of the Aalensis Biozone in the upper Toarcian, and the Opalinum and Comptum subzones of the Opalinum Biozone in the lower Aalenian). With regard to the benthic foraminifera, the taxa identified have enabled the Astacolus dorbignyi Zone and 11 bioevents to be identified...

Analysis of foraminifera assemblages and sediment geochemical properties to characterise the environment near Araca and Saco da Cape la domestic sewage submarine outfalls of Sao Sebastiao Channel, Sao Paulo State, Brazil

TEODORO, A. C.; DULEBA, W.; GUBITOSO, S.; PRADA, S. M.; LAMPARELLI, C. C.; BEVILACQUA, J. E.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.51%
Superficial bottom samples were collected near diffusers of domestic sewage submarine outfalls at Araca and Saco da Capela, Sao Sebastiao Channel, Brazil. The goal of this study was to investigate the distribution and composition of live benthic foraminifera assemblages and integrate the results obtained with geochemical analyses to assess human-induced changes. According to the results obtained no environmental stress was observed near the Saco da Capela submarine outfall diffusers. The foraminifera assemblage is characterised by species typical of highly hydrodynamic environments, with well-oxygenated bottom waters and low nutrient contents. In contrast, near Araca submarine outfall, organic enrichment was denoted by high phosphorus, sulphur and, to a lesser extent, total organic carbon content. Harmful influences on foraminifera could be identified by low richness and specific diversity, as well as the predominance of detritivore feeder species, which are associated with higher organic matter flux and low oxygen in the interstitial pore water. (C) 2009 Elsevier Ltd. All rights reserved.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, Brazilian agency)

"Distribuição de foraminíferos planctônicos (0 - 100m na coluna d'água) e seu registro no sedimento na margem continental sudeste brasileira, entre São Sebastião, SP, e Cabo de São Tomé, RJ"; Distribution of planctonic foraminifera (0 m - 100 m in the water column) and theirsedimentary record on the Southeastern Brazilian continental margin, between São Sebastião Island, SP, and São Tomé Cabe, RJ

Sorano, Maria Regina Goncalves de Souza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/12/2006 PT
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37.57%
O presente trabalho tem como enfoque o estudo de foraminíferos planctônicos, na margem continental Sudeste Brasileira, entre São Sebastião, SP e Cabo de São Tomé, RJ através do levantamento das espécies existentes no plâncton. Buscou conhecer a distribuição sazonal e vertical na coluna d?água (0 a 100 m de profundidade) das espécies de foraminíferos planctônicos, correlacionar a presença desses organismos a fatores abióticos e bióticos no meio ambiente. Comparar a composição da biocenose e da tanatocenose assim como, realizar análise tafonômica das carapaças depositadas no fundo oceânico, a fim de avaliar o registro sedimentar desses organismos e considerar a utilização de assinaturas tafonômicas em carapaças de foraminíferos planctônicos na compreensão dos processos hidrodinâmicos na área de estudo. Para isso, foram analisadas amostras de plâncton, coletadas no verão/2002 e inverno/2002, e amostras de sedimento. Foram aplicadas metodologias usuais em análises de foraminíferos planctônicos. Foi possível reconhecer que há grande diferença sazonal na abundância e no tamanho de foraminíferos planctônicos na margem continental Sudeste Brasileira. A distribuição vertical desses organismos no verão parece estar relacionada à profundidade da camada de mistura...

Reconstituição paleoambiental das enseadas do Flamengo e da Fortaleza, Ubatuba, S.P., durante o Holoceno, inferida a partir da variação das associações de foraminíferos; Paleoenvironmental reconstitution of Flamengo and Fortaleza bays, Ubatuba, SP, during the Holocene, inferred from the variations of Benthic foraminifera associations

Silva, Juliana Braga
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/04/2008 PT
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37.42%
A partir do padrão de distribuição das associações de foraminíferos ao longo de dois testemunhos e da sua correlação com características abióticas do sedimento, detectaram-se variações ambientais holocênicas ocorridas em dois embaiamentos marinhos rasos: as enseadas do Flamengo (Testemunho UB1) e da Fortaleza (Testemunho UB3), em Ubatuba, SP. Posteriormente, correlações foram estabelecidas entre as mudanças da composição faunística e curvas de variação do nível do mar existentes na literatura. O testemunho UB1 possui 222 cm de profundidade e foi coletado no Saco da Ribeira sob lâmina de água de 3,10 m. É constituído predominantemente por sedimentos sílticos que contêm fragmentos vegetais e biodetríticos. Camadas arenosas são encontradas em sua base, datada em 7290 + 40 anos A.P., e à profundidade compreendida entre 32 e 12 cm. O testemunho UB3 tem 342 cm de profundidade e foi coletado na Praia do Lázaro sob lâmina de água de 3,80 m. Seus sedimentos são predominantemente sílticos, contendo fragmentos vegetais, fragmentos vegetais oxidados e fragmentos biodetríticos. Seqüências arenosas e arenosiltosas são encontradas em sua base, datada em 7.530 + 40 anos A.P., e entre 32 e 12 cm de profundidade. Foram identificados 76 espécies e 40 gêneros de foraminíferos bentônicos e uma espécie de foraminífero planctônico nas 58 amostras analisadas...

Estudo das associações de foraminíferos bentônicos recentes na Baía do Almirantado (Ilha Rei George, Antártica) durante três verões austrais consecutivos; Study of the recent benthic Foraminifera assemblages from Admiralty Bay (King George Island, Antartica) during three consecutive austral summers

Rodrigues, André Rosch
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/08/2008 PT
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A região antártica é foco de constante observação por ser uma região de importante monitoramento climático global. Ao sedimento de fundo marinho está associada uma biota que responde aos processos de alterações ambientais e dentre seus representantes os foraminíferos são considerados bons indicadores marinhos. O objetivo do presente estudo é avaliar a fauna de foraminíferos recentes na Baía do Almirantado durante três verões austral consecutivos (2002/2003, 2003/2004 e 2004/2005) e, através da determinação de algumas variáveis ambientais, compreender melhor a ecologia e a distribuição desses organismos na região. Foram coletadas 56 amostras de sedimento de fundo marinho ao longo da Baía do Almirantado para análise e identificação da fauna de foraminíferos e de variáveis abióticas amostradas na água de fundo e no sedimento. Foram encontradas 66 espécies de foraminíferos bentônicos, sendo 36 espécies aglutinantes e 30 espécies calcárias. As espécies mais freqüentes foram as calcárias Bolivina pseudopunctata, Cassidulinoides parkerianus e Globocassidulina biora, e as aglutinantes Portatrochammina antarctica, Pseudobolivina antarctica e Spiroplectammina biformis. As espécies Portatrochammina antarctica e Pseudobolivina antarctica foram as mais abundantes na porção central e em algumas estações das três enseadas da baía. As regiões mais internas das enseadas apresentaram predominância de espécies hialinas principalmente do gênero Globocassidulina e Cassidulinoides. A predominância de espécies hialinas também foi observada nas estações próximas a desembocadura da Baía do Almirantado com as espécies Bolivina pseudopunctata e Fursenkoina fusiformis.; The Antarctic region is focus of constant scientific surveys because of its importance as global climate changing area. The marine bottom sediment has an associated biota that indicates some environmental changes and among them Foraminifera could be considered as one of the best marine biomarkers. The aim of the present study is describe the recent benthic foraminifera fauna from Admiralty Bay collected during three consecutive austral summers (2002/2003...

Distribuição dos foraminíferos bentônicos vivos no talude continental e Platô de São Paulo, Bacia de Campos (23º 12'-24º 30'S e 39º59'-41º 20'W): fatores ambientais condicionantes; Distribution of living benthic foraminifera on the continental slope and Plateau of São Paulo, Campos Basin (23º 12'24º 30' and 39º 59'41º20"): controlling environmental factors

Yamashita, Cintia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/06/2011 PT
Relevância na Pesquisa
37.42%
O presente estudo compreende a análise de distribuição dos foraminíferos bentônicos vivos no talude continental da Bacia de Campos e Platô de São Paulo, procurando compreender os fatores ambientais condicionantes dessa distribuição. Amostras de sedimento foram coletadas, entre 400 e 3000 m de profundidade, no outono/inverno de 2008, e verão de 2009. Dados sedimentológicos, geoquímicos e microfaunísticos permitiram identificar dois setores na área de estudo. O Setor I inclui amostras do talude superior e médio (400-1300 m de profundidade), e é caracterizado por valores altos de densidade, diversidade, densidade das espécies de foraminíferos bentônicos indicadoras de produtividade (BFHP), de carbono orgânico, e pela presença de espécies como Adercotryma wrighti, Globocassidulina subglobosa e Pullenia bulloides, refletindo maior disponibilidade de alimento, com fluxos episódicos de fitodetritos. O setor II, constituído de amostras do talude inferior e Platô de São Paulo (1300-3000 m de profundidade), é caracterizado por baixos valores de densidade, diversidade, BFHP e de carbono orgânico, com predomínio de espécies epifaunais, indicando condições mais oligotróficas. O oxigênio não se mostrou um fator restritivo à distribuição da microfauna...

Relações entre a biomassa dos foraminíferos bentônicos vivos e modelos de fluxo vertical de partículas orgânicas na região da Bacia de Campos - RJ; Relations between the biomass of benthic foraminifera living and models of vertical flux of organic particles in the region of the Campos Basin - RJ

Vicente, Thaisa Marques
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/12/2012 PT
Relevância na Pesquisa
37.57%
Este trabalho tem como meta investigar a relação entre o fluxo vertical de matéria orgânica particulada (MOP) e a biomassa de foraminíferos bentônicos vivos na região do talude da Bacia de Campos/RJ (400 a 3000m). O fluxo vertical de MOP para o assoalho oceânico foi inferido através de modelos que utilizam dados de sensoriamento remoto, como estimativas da concentração de clorofila a, valores de temperatura da superfície do mar e produtos derivados destes (i.e. produção primária e determinação de classes de tamanho do fitoplâncton), enquanto que a biomassa de foraminíferos bentônicos foi estimada através da técnica de biovolume. Os resultados indicam que as estimativas de fluxo se correlacionaram com os conteúdos de carbono orgânico total (COT) no sedimento, com a biomassa total de 19 espécies de foraminíferos bentônicos e com a biomassa, sendo que a distribuição de biomassa dessas espécies evidencia além da quantidade de MOP, a qualidade da MOP (labilidade). A distribuição dos valores de fluxo vertical e biomassa total de foraminíferos bentônicos estão atreladas às feições de mesoescala (meandros e vórtices de Cabo Frio e Cabo de São Tomé), que propiciam o aumento de produtividade primária e o crescimento do microplâncton...

Novel lineages of Southern Ocean deep-sea foraminifera revealed by environmental DNA sequencing

Pawlowski, Jan; Fontaine, Delia; da Silva, Ana Aranda; Guiard, Jackie
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.51%
Diversity of deep-sea foraminifera is commonly studied based on analysis of agglutinated and calcareous tests preserved in the dried sediment samples. Soft-walled and agglutinated monothalamous (single-chambered) foraminifera are usually ignored because they are poorly preserved and difficult to identify. Moreover, the assemblage examined is usually limited to sediment size fraction larger than 63 or 125 mu m. To overcome these problems, we analysed the foraminiferal assemblage based on ribosomal DNA sequences amplified specifically from total DNA extracted from unsieved and fine fraction (<32 mu m of sediment samples from three sites in Southern Ocean. We obtained 392 sequences, representing 123 phylotypes of foraminifera. Over 90% of phylotypes (112) could not be assigned to any previously sequenced species or genera. Among these new phylotypes, 20 belong to the clade of multi-chambered calcareous Rotaliida and agglutinated Textulariida, while 94 branch among the radiation of monothalamous species. Many new phylotypes clustered together with other environmental foraminiferal sequences and sequences of unknown origin. Eight new lineages of environmental foraminiferal sequences (ENFOR 1-8) were distinguished. The morphology of species included in these novel lineages is unknown...

The response of benthic foraminifera to pollution and environmental stress in Ria de Aveiro (N Portugal); La respuesta de los foraminíferos bentónicos a la contaminación y el estrés ambiental en la Ría de Aveiro (N de Portugal)

Martins, V.; Yamashita, C.; Sousa, S. H. M.; Martins, P.; Laut, L. L. M.; Figueira, R. C. L.; Mahiques, M. M.; Silva, E. F. da; Dias, J. M. A.; Rocha, F.
Fonte: Universidad Complutense de Madrid Publicador: Universidad Complutense de Madrid
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.51%
This work evaluates the quality of the sediment in Ria de Aveiro, a coastal lagoon located at N of Portugal that is under strong anthropic influence, and the effects of the contamination on benthic foraminifera. The initial approach for measuring pollution was done through the load pollution index (LPI), based on As, Cd, Cr, Cu, Ni, Pb and Zn concentrations, and determined by total digestion of the sediments (TDS). This information was complemented by conducting a metal fractionation technique (sequential chemical extraction - SCE) in some of the most contaminated samples in order to define the relevance of different metal bearing- phases (exchangeable cations adsorbed by clay and co-precipitated with carbonates, absorbed by organic matter and retained in the mineralogical phase) and to evaluate the toxic heavy metal availability. Multivariable statistical analyses were carried out taking into consideration the geochemical results, as well as the biotic (percentage of species/groups of species; foraminifer abundance and diversity) and abiotic variables, such as sediment content in mud, total organic carbon (TOC) and Eh. SCE results show that most of the element concentration in the sediments is retained in the resistant mineralogical phase. How - ever...

Benthic foraminifera distribution in high polluted sediments from Niterói Harbor (Guanabara Bay), Rio de Janeiro, Brazil

Vilela,Claudia G.; Batista,Daniele S.; Batista-Neto,José A.; Crapez,Mirian; Mcallister,John J.
Fonte: Academia Brasileira de Ciências Publicador: Academia Brasileira de Ciências
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2004 EN
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Dockyards and harbors are recognized as being important locations where sediment-associated pollutants can accumulate, which constitutes an environmental risk to aquatic life due to potential uptake and accumulation of heavy metals in the biota. The aim of this paper is to assess the concentrations and the effects of some heavy metals in the benthic foraminifera assemblage in Niterói Harbor. Low concentrations in the benthic foraminifera as well as the dominance of indicative species such as Ammonia tepida, Buliminella elegantissima and Bolivina lowmani can be associated with an environment under stress. In addition, the occurrence of test abnormalities among foraminifera may represent a useful biomarker for evaluating long-term environmental impacts in a coastal region.

Late Aptian-Albian of the Vocontian Basin (SE-France) and Albian of NE-Texas: Biostratigraphic and paleoceanographic implications by planktic foraminifera faunas; Das Apt und Alb des Vokontischen Beckens (SE-Frankreich) und das Alb von NE-Texas: Biostratigraphische und Paleozeanographische - Ergebnisse anhand von planktischen Foraminiferen

Reichelt, Kerstin
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
37.42%
Planktic foraminifera fauna and carbon isotopes of the bulk rock have been investigated to compile a high resolution biostratigraphy for the Late Aptian to Late Albian in the Vocontian Basin (SE-France) and for the Middle and Late Albian in NE-Texas. A high resolution carbon isotope stratigraphy (CIS) has been established for the Albian of the Vocontian Basin, and partially correlated with sections in the eastern (ODP 547, Mazagan Plateau) and western (ODP 1052; Blake Nose Plateau) Atlantic as well as in the Gulf of Mexico (NE-Texas). The high resolution carbon isotope stratigraphy possibly revealed diachronous first appearances of stratigraphically well constrained planktic foraminifera in the Vocontian Basin (western Tethys), at the Mazagan Plateau (eastern Atlantic), the Blake Nose Plateau (western Atlantic), and NE-Texas (Gulf of Mexico). The causes for the non-simultaneous occurrences may be palaeoceanographic and palaeoclimatic changes, which may have affected the water current system, the water column structure and the nutrient distribution. In addition, the planktic foraminiferal data of the first appearance in NE-Texas show that the evolution of planktic foraminifera in NE-Texas may depend highly on transgression/regression cycles.; Zur Entwicklung einer hochauflösenden Biostratigraphie des Ober Apt bis Ober Alb des Vokontischen Beckens (SE-Frankreich) und des Mittel bis Ober Alb in NE-Texas wurden planktische Foraminiferen und stabile Isotope des Kohlenstoffs untersucht. Basierend auf Korrelationen der Kohlenstoffisotopenkurve aus SE-Frankreich...

Planktonic foraminifera transfer function approach to Red Sea paleoceanography; Quantitative Paläoklimarekonstruktionen anhand von Vergesellschaftungen planktischer Foraminiferen im Roten Meer

Siccha, Michael
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
37.65%
This study examines the potential of using the assemblage composition of planktonic foraminifera in the Red Sea as a quantitative proxy for paleoclimate reconstructions. To this end, a new surface sediment sample dataset was generated to evaluate the environmental control on foraminifera assemblages and to serve as the calibration dataset for the subsequent development of planktonic foraminifera transfer functions. Gradient analysis was employed to investigate the effect of temperature, salinity, primary productivity, water column stratification and the properties of the oxygen minimum zone on the foraminifera fauna of the Red Sea. Because of the high mutual correlation among all environmental parameters along the basin axis, no unambiguous identification of the controlling parameter could be achieved by statistical analyses of the calibration dataset alone. A comparison with published studies on the ecology of planktonic foraminifera, however, lead to the working hypothesis that primary productivity determines the distinct gradient in the foraminifera community in the Red Sea. Transfer functions were then generated by four mathematical methods to characterise the relationship between foraminifera assemblages and chlorophyll a concentration as a proxy for productivity. The transfer functions appear highly efficient in capturing the modern productivity gradient in the Red Sea...

Experimental in-situ phytodetritus pulses: response and assemblage of benthic deep-sea foraminifera; In-situ Fraßexperimente in der Tiefsee - Vergesellschaftungen von rezenten Foraminiferen und deren Reaktion auf Nahrungsverfügbarkeit

Enge, Annekatrin
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
37.75%
Foraminifera are an important component of the benthic deep-sea fauna whose distribution and occurrence mainly depends on the availability of food and oxygen concentration. Most deep-sea foraminifera depend on organic matter as food source which was produced in the photic zone of the oceans and has sunk to the sea floor. The flux of organic matter varies strongly with water depth but also on a seasonal scale. Deposits of fresh phytodetritus on the sediment floor in the deep sea after a strong spring production are a temporarily limited food source whose effect on the benthic deep-sea community has only scarcely been investigated so far. To study the response of foraminifera to such a deposition event, two in-situ feeding experiments were carried out: one in the Northeast Pacific (3985 m) and one in the Arabian Sea within the Oxygen Minimum Zone (540 m). To simulate a phytodetritus sedimentation event, algal material was injected onto a defined sediment area directly at the sea floor to allow feeding by foraminifera for four days. Prior the experiment, algae were labeled with stable isotopes (13C, 15N) to allow the tracking of the food source to the foraminifera. This approach also allows the calculation of uptake rates for foraminifera which are comparable to other feeding experiments and faunal groups. In addition to the feeding experiment...

Foraminifera and coccolithophorid assemblage changes in the Panama Basin during the last deglaciation: Response to sea-suface productivity induced by a transient climate change

Martinez, J Ignacio; Rincon, Daniel; Yokoyama, Yusuke; Barrows, Timothy
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The responses of community assemblages of planktonic and benthonic foraminifera and coccolithophorids to transient climate change are explored for the uppermost 2 m of cores ODP677B (1.2°N; 83.74°W, 3461 m) and TR163-38 (1.34°S; 81.58°W, 2200 m), for

Paleoceanographic conditions in the western Caribbean Sea for the last 560 kyr as inferred from planktonic foraminifera

Martinez, J Ignacio; Mora, German; Barrows, Timothy
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Faunal analyses of planktonic foraminifera and upper-water temperature reconstructions with the modern analog technique are studied and compared to the magnetic susceptibility and gamma ray logs of ODP Core 999A (western Caribbean) for the past 560 kyr i

Planktonic foraminifera and their proxies for the reconstruction of surface ocean climate parameters

Mortyn, Peter Graham; Martínez Botí, M. A.
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2008 ENG
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Planktonic foraminifera are useful organisms to assess the surface ocean’s role in climate change, due to their upper water column habitat, calcium carbonate mineral structure, and preservation in the deep-sea sedimentary record. Carbonate sediments rich in the calcitic shells of foraminifera are abundant in both space and time, which allows their use in an array of paleoceanographic studies over time scales ranging from decadal to glacial-interglacial, as well as beyond and between. Here we review the most important “proxy” methods to reconstruct surface-ocean climatic variables using planktonic foraminifera. These methods include assemblage-based and geochemical-based (both isotopic and elemental) approaches. The natural emphasis is on temperature, the most important climatic parameter of the surface ocean, although related physical, chemical, and biological properties are addressed as well, such as salinity, productivity, nutrient utilization, weathering, circulation, and oceanic C-system properties including alkalinity, pH, and [CO3 2-]. In our systematic evaluation of each foraminiferal proxy, we provide the basis for each method, brief examples, and a glimpse into the future, when current research needs will hopefully be met.; Els foraminífers planctònics són organismes que permeten avaluar el paper que té la superfície dels oceans en el procés de canvi climàtic...

Reconstruction of a latest Paleocene shallow-marine eutrophic paleoenvironment at Sidi Nasseur (Central Tunisia) based on foraminifera, ostracoda, calcareous nannofossils and stable isotopes (d13C, d18O)

Stassen, P.; Dupuis, C.; Morsi, A.M.; Steurbaut, E.; Speijer, R.P.
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2009 ENG
Relevância na Pesquisa
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In order to unravel faunal and paleoenvironmental parameters in shallow marine settings prior to the Paleocene- Eocene thermal maximum, we investigated the Sidi Nasseur section (NAS) in Central Tunisia. This section exposes Paleocene to lower Eocene shales and marls of the El Haria Formation. The uppermost Paleocene part of the Sidi Nasseur section is marked by poor to moderately rich, but fairly diversified nannofossil associations, containing the typical latest Paleocene taxa of the top of NP9a. The ostracode record displays an almost continuous record in the uppermost Paleocene part of the section. Representatives of Aegyptiana, Paracosta, Reticulina and Reymenticosta make up the major part of the ostracode fauna. The benthic foraminiferal assemblage consists of numerous small calcareous benthic foraminifera, like Anomalinoides midwayensis and Lenticulina spp. and many large Frondicularia phosphatica, Pyramidulina spp. These, together with the non-calcareous agglutinated foraminifera and the rare planktic foraminifera, indicate an inner neritic to coastal environment with eutrophic conditions, regularly interrupted by oxygen deficiency. The dominance of non-calcareous benthic foraminifera between intervals with abundant calcareous benthic foraminifera suggests post-mortem dissolution. The foraminiferal d13C record (based upon Pyramidulina latejugata) of the latest Paleocene in the Sidi Nasseur area is very similar to these from coeval sediments at Gebel Duwi and Gebel Aweina in Egypt. Oxygen isotopic ratios indicate a marine setting with a water composition affected by evaporation. During the latest Paleocene...

Megalodon, mako shark and planktonic foraminifera from the continental shelf off Portugal and their age

Antunes, Miguel Teles; Legoinha, P.; Balbino, A.
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2015 ENG
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A turbidite specimen collected by a fishing net off the Portuguese coast presents some fossils. A process of condensation is revealed by Late Pliocene and Quaternary typical foraminifera. The matrix is phosphatised and rather iron-rich with small quantities of manganese and zinc and even less copper. Based on planktonic foraminifera in depressions of cetacean skulls from the same area, the fossilization of shark and cetaceans is likely to have occurred in the uppermost Messinian to Early Pliocene. Lack of benthic foraminifera also point out to more or less deep environments, while a scallop, Mimachlamys varia, indicates nearby rocky environments. The occurrence of Megaselachus megalodon excludes an older than Miocene age and most probably, even an older than Middle Miocene age. Its very advanced evolution stage is consistent with a Pliocene age. The mako shark, Isurus cf. oxyrhinchus is recorded here for the first time. The shark association represents a seemingly moderately warm indicator as megalodon and Isurus are essentially temperate water dwellers, while no warm water form is known. Hence temperate to moderately warm conditions seem to have prevailed.

The distribution of deep-sea benthic foraminifera in core tops from the eastern Indian Ocean

Murgese, David; De Deckker, Patrick
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
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Relative abundances of benthic foraminifera in 57 core tops collected within a depth-range between 700 and 4335 m below sea level [b.s.l.] from the eastern Indian Ocean (mostly between Australia and Indonesia) were investigated quantitatively using Detrended Correspondence Analysis (DCA) to analyse species spatial-distribution. Canonical Correspondence Analysis (CCA) and correlation matrices were used to evaluate the relationships between the species distribution and environmental variables (temperature, salinity, dissolved oxygen, nitrate and phosphate concentrations, carbon-flux rate). Seven key-species proved useful for distinguishing environmental parameters. Two groups of species are identified by means of the first DCA ordination axis. The first group increases in relative abundances with depth and includes three taxa: Oridorsalis tener umbonatus, Epistominella exigua and Pyrgo murrhina. These three taxa prefer a cold (< 3°C) and well-oxygenated (> 3.5 ml/l) environment, with low carbon flux to the sea floor (< 3 g C m-2 year-1). O. tener umbonatus and P. murrhina tend to indicate reduced food availability, whereas E. exigua may indicate periodic delivery (seasonal) of organic matter to the sea floor. The second group includes Nummoloculina irregularis and Cibicidoides pseudoungerianus...

Morphological Abnormalities and Dwarfism in Maastrichtian Foraminifera from the Cárdenas Formation, Valles-San Luis Potosí Platform, Mexico: evidence of paleoenvironmental stress

Omaña,Lourdes; Alencáster,Gloria; Torres Hernández,José Ramón; López Doncel,Rubén
Fonte: Sociedad Geológica Mexicana, A.C. Publicador: Sociedad Geológica Mexicana, A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
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During the early Maastrichtian an assemblage rich in large foraminifera, mostly composed of orbitoidal foraminifera, developed in the shallow-water deposits of the Cárdenas Formation (Valles-San Luis Potosí Platform, Mexico). Among them, the most abundant is Lepidorbitoides minima, some of which display a morphologically abnormal test consisting of polyvalent forms, conical tests and budding, which could be induced by abrupt changes in environmental factors. The occurrence of the abnormalities preceded the demise of this species and of all the larger foraminiferal association in the upper part of the Gansserina gansseri Zone (early Maastrichtian). The abnormalities could be induced by environmental stress, probably related to interplay of different events such as increased terrigenous input and the transition to deeper facies due to Laramide tectonic instability before the K/P boundary. A late Maastrichtian community of dwarfed planktic foraminifera composed of Trinitella scotti Bronnimann, Plummerita reicheli Bronnimann, Rugoglobigerina cf. macrocephala Bronnimann, Rugoglobigerina hexacamerata Bronnimann, Heterohelix punctula-ta (Cushman), Pseudoguembelina costulata (Cushman), Pseudotextularia intermedia de Klasz, Globigerinelloides asperus Bolli...