Siluro-Devonian graptolite stratigraphy of the Catalonian Coastal Ranges

Two facies characterize the Silurian and lower Devonian of the Catalonian Coastal Ranges, namely euxinic and pelagic carbonate facies. The first, is represented by black shales in which the atavus, acinaces, cyphus, triangulatus, convolutus, ?sedgwickii, ellesae and tumescens zones have been recognized. The graptolite succesion is far from complete on present evidence, but this is probably due to unfavorable environmental (taphonomic) conditions. This facies is similar to that prevailing throughout the Iberian massif and most of western Europe. The pelagic carbonate facies is peculiar to the Pridoli and lower Devonian and corresponds to the facies type prevailing in the Western Mediterranean Area. It is characterized by the nodular texture of limestones and marls, with all gradations between nodular limestones, marls and slates. Massive nodular limestone, occur in the lower part of the sequence (La Creu Formation) while the alternation of limestones, marls and slates charaterizes the upper part (Olorda Formation). Orthoconic cephalopds, crinoids, conodonts and tentaculites are the most common fossils present; graptolites occur in some shale horizons in the lower part of the Olorda Formation. These graptolites give strong indications of the uniformis and hercynicus zones (Lochkovian). The uppermost part of the sequence has not provided any graptolite fauna, but according their dacrioconarid fauna it corresponds probably to the Pragian.

Significado paleobiológico de agrupamentos (coloniais/ gregários) de Conularia quichua Ulrich, 1890 (Cnidaria), Formação Ponta Grossa, Devoniano (Pragiano-Emsiano), Bacia do Paraná, Brasil

The Conularia beds of the Ponta Grossa Formation (Devonian) of the Paraná Basin, southern Brazil, yield well-preserved specimens of Conularia quichua Ulrich and Paraconularia africana Sharpe. Many of these are preserved in life orientation. Also, one of the C. quichua specimens has five faces instead of four, providing additional evidence of a cnidarian affinity for conulariids. Conulariids occur in the Jaguariaíva Member (or Sequence B, transgressive system tract) containing several obrution deposits beneath marine flooding surfaces. Taphonomic data obtained from these beds show conclusively that both C. quichua and P. africana were epibenthic, sessile invertebrates originally oriented with their long axis perpendicular to the bottom and with their aperture opening upward. Of the 136 C. quichua specimens examined here, 125 occur isolated. Eleven of the C. quichua specimens collectively occur in five discrete clusters consisting of two or three specimens. All of the clustered specimens are fully inflated (exhibiting a rectangular transverse cross section) or slightly compressed longitudinally. In all of these specimens the apex is missing, and thus the problem of whether the clusters were clonal colonies or formed through preferential larval settlement cannot be resolved conclusively. However, in the single cluster consisting of three specimens, the specimens are oriented perpendicular to bedding, and thus they do not converge adapically. The three specimens are in contact with each other along the upper portion of their median region. These and the lack of any evidence of a sheet of budding stolons, suggest that this cluster was formed by preferential larval settlement. © Asociación Paleontológica Argentina.

Metacryphaeus rotundatus, um novo elemento da fauna de trilobites calmoniidae (phacopida), da formação Ponta Grossa (Devoniano), bacia do Paraná, Brasil

Calmoniids (Delo, 1935) are the most common and abundant group of trilobites of the fossil record of the Devonian Ponta Grossa Formation in the Apucarana sub-basin. Although known since the past century, the study of calmoniids has been taxonomically and stratigraphically biased. This is because some authors centered their studies on some particular genera from a few stratigraphic horizons within the basal portion of the Ponta Grossa Formation. The analyses of 398 specimens of calmoniid trilobites of the rocks of Jaguariaiva Member of the Ponta Grossa Formation, mainly from Tibagi county in the state of Paraná, Brazil, indicate the presence of specimens that are referable to Metacryphaeus rotundatus (Kozlowski, 1923). This is the first record of M. rotundatus in Brazilian Devonian rocks. Metacryphaeus rotundatus is a conspicuous species of the Emsian rocks of the Icla Formation, Bolivia. Although the affinities of the trilobite fauna of the Devonian Paraná Basin, in the context of the Malvinokaffric realm, are with the Brazilian and South Africa provinces, this finding is in accordance with new evidence (e.g., conulariids, homalonotids trilobites), indicating the presence of cosmopolitan species with Andean affinities. Metacryphaeus rotundatus lived in a broad paleoclimatic range, from a temperate, cold temperate to a subpolar climate. Finally, in the Devonian of the Paraná Basin, M. rotundatus lived and were preserved in muddy, organic rich bottoms, deposited in offshore waters, below the storm wave base, associated to marine flooding surfaces.

Levantamento histórico da Classe Tentaculitoidea no Devoniano brasileiro: principais características e padrões de preservação

This work deals with the historical survey of the class for the Devonian layers, general characteristics of the group and taphonomic preservation standards associated with the group. It was analyzed specimens of scientific collections from brazilian museums and universities. The taxonomic group is represented by four genera in the basins of Parana, Parnaiba and Amazon: Tentaculites, Homoctenus, Styliolina and Volynites. The tentaculitids occur from Ordovician to the Devonian, having its peak in the Middle Devonian. The class has three known orders: Tentaculitida, animals of benthic habit, Homoctenida and Dacryoconarida, animals of habit planktonic. It was also noticed the presence of two patterns of taphonomic conservation: isolated and grouped specimens.

Analisi di conodonti al limite Devoniano/Carbonifero (sezione stratigrafica di Col du Puech de la Suque Est, Montagne Noire, Francia)

Sono stati analizzati alcuni campioni provenienti dalla sezione stratigrafica di Col du Puech de la Suque (Montagne Noire, Francia Meridionale), raccolti in un intervallo comprendente il limite Devoniano/Carbonifero allo scopo di individuare il limite stesso in base alla identificazione e attribuzione biostratigrafica dei conodonti rinvenuti. Sono stati discussi i problemi che caratterizzano la definizione del limite e si è fornita una possibile soluzione.

Contribuição para ao estudo do Devoniano paranaense

O Devoniano ocorrente nos Estados do Paraná e São Paulo, Brasil, é de longa data conhecido; contudo os dados sobre a sua estratigrafia são até hoje escassos. Particular atenção foi ultimamente dada a este problema, considerando além das regiões clássicas, mais uma nova, Lambedor, que só se tornou conhecida como fossilífera em 1946. Os resultados obtidos permitem considerar acima do arenito basal afossilífero Furnas, camadas de transição com fósseis escassos, consistindo, na vila de Tibagi, de pequenas intercalações de folhelho em arenito grosseiro, o qual se torna argiloso e fossilífero mais no topo. Em Jaguariaíva, estas camadas são constituídas de siltito, passando superiormente a arenito fino, ambos fossilíferos. Estas camadas de transição são seguidas por folhelhos fossilíferos com intercalações arenosas - formação Ponta Grossa. A descoberta nas secções de Tibagi e Lambedor, de repetições de arenito litológica e faunisticamente comparáveis a um arenito colocado anteriormente no topo da formação Ponta Grossa com o nome de arenito de Tibagi, e a ausência do mesmo em Jaguariaíva, onde afloram quase 100 metros de sedimentos fossilíferos, indica a natureza restrita do mesmo. Acima do arenito de Tibagi e do folhelho intercalado, segue uma seqüência de folhelhos fossilíferos, a qual, em Lambedor, é capeada por siltito com intercalações de arenito com fósseis devonianos. Este arenito parece ter uma ocorrência muito local e restrita. Sobre este arenito devoniano em Lambedor e sobre o folhelho sotoposto em Tibagi, ocorre uma seqüência de arenitos grosseiros afossilíferos com intercalações de arenito mais fino e com estratificação cruzada e formando escarpas. Este arenito é um tanto parecido com o Furnas, e a ele equiparado por uns, evocando para isto falhas hipotéticas e por outros colocado no topo do Devoniano, com o nome de arenito Barreiro, e por outros ainda no Carbonífero (Série Itararé-Tubarão). As seguintes razões permitem considerá-lo como pertencente à base da série Itararé-Tubarão (Série Carbonífera com parte dos sedimentos de origem glacial ou flúvio-glacial): 1) - Grandes seixos angulares na base, em Tibagi. 2) - Varvito na base, intercalado em arenito, em Lambedor. 3) - Seixos angulares e estriados no meio da massa arenítica, em Lambedor. 4) - Disconformidade indicada pela posição deste arenito respectivamente sobre o siltito superior devoniano, arenito fácies Tibagi e sobre folhelho devoniano acima ou abaixo deste arenito, em Lambedor. Certas variações faunísticas, pelo menos em parte, apenas de natureza geográfica, foram notadas nas 4 principais localidades: - Ponta Grossa, Tibagi, Lambedor e Jaguariaíva. Minuciosos perfis geológicos com a discriminação dos fósseis por camada, foram feitos e a maioria da fauna devoniana descrita por Clarke (1913), e outros autores, teve a sua distribuição estratigráfica, pelo menos parcialmente esclarecida.

Notes on the Siluro-Devonian Ischadites stellatus (Fagerstrom 1961), a Dasycladaceous Alga / [by] Matthew H. Nitecki.

v.23:no.3(1971)

Análise estratigráfica de subsuperfície do Devoniano Inferior da Bacia do Rio do Peixe, Nordeste do Brasil

Subsurface stratigraphic analysis of Devonian strata from the Rio do Peixe Basin, newly recognized by palynological studies, has resulted in the identification of two new lithostratigraphic units assembled in the Santa Helena Group. The Pilões Formation, the lower unit, is composed mainly of dark mudstones and medium-tovery fine-grained sandstones, with minor conglomerates and breccias. The Triunfo Formation, the upper unit, comprises whitish grey, kaolinitic, coarse-grained to conglomeratic, cross stratified sandstones and conglomerates, with interbedded mudstones and fine-grained sandstones. These units were characterized using cores, sidewall and cuttings samples, conventional logs and image log, from three wells drilled by PETROBRAS, and 3D seismic data. The Pilões Formation is interpreted as prodeltaic facies, with lesser associated subaqueous talus, debrite and sandy turbidite lobe facies, distal part of fandelta and braided fluviodeltaic facies of Triunfo Formation. The Santa Helena Group corresponds to the Lower Devonian tectono-sequence deposited in a NW-SE-trending graben during a transgressiveregressive cycle. With 343 meters of thickness (isochore) in well 1-PIL-1-PB (Pilões 1), this sequence has a non-conformity at the lower boundary and its upper boundary is an unconformity with the Lower Cretaceous tectono-sequence (Rio do Peixe Group), that represents a hiatus of about 265 million years. Ignimbrites and coignimbrite breccias (Poço da Jurema volcanic breccia), related to an unknown pyroclastic volcanic event, were recognized at the northern margin of the Sousa halfgraben. Evidence from well data suggests that this event is coeval with the Devonian graben filling. The present study indicates a polyhistorical tectono-volcanosedimentary evolution of the basin. This lithostratigraphic update brings new perspectives for geological research in the Rio do Peixe Basin, as well as in other inland basins of the Northeastern of Brazil. The results of the research also contribute to the kwnoledge of the Borborema Province and western Gondwana paleogeography during the Early Devonian.

Towards an understanding of the age and origin of mesothermal gold mineralisation in the Etheridge Goldfield, Georgetown region, north Queensland

Small mesothermal vein quam-gold-base-metal sulfide deposits from which some 20 t of Au-Ag bullion have been extracted, are the most common gold deposits in the Georgetown region of north Queensland-several hundred were mined or prospected between 1870 and 1950. These deposits are mostly hosted by Proterozoic granitic and metamorphic rocks and are similar to the much larger Charters Towers deposits such as Day Dawn and Brilliant, and in some respects to the Motherlode deposits of California. The largest deposit in the region-Kidston (> 138 t of Au and Ag since 1985)- is substantially different. It is hosted by sheeted quartz veins and cavities in brecciated Silurian granite and Proterozoic metamorphics above nested high-level Carboniferous intrusives associated with a nearby cauldron subsidence structure. This paper provides new information (K-Ar and Rb-Sr isotopic ages, preliminary oxygen isotope and fluid-inclusion data) from some of the mesothermal deposits and compares it with the Kidston deposit. All six dated mesothermal deposits have Siluro-Devonian (about 425 to 400 Ma) ages. All nine of such deposits analysed have delta(18)O quartz values in the range 8.4 to 15.7 parts per thousand, Fluid-inclusion data indicate homogenisation temperatures in the range 230-350 degrees C. This information, and a re-interpretation of the spatial relationships of the deposits with various elements of the updated regional geology, is used to develop a preliminary metallogenic model of the mesothermal Etheridge Goldfield. The model indicates how the majority of deposits may have formed from hydrothermal systems initiated during the emplacement of granitic batholiths that were possibly, but not clearly, associated with Early Palaeozoic subduction, and that these fluid systems were dominated by substantially modified meteoric and/or magmatic fluids. The large Kidston deposit and a few small relatives are of Carboniferous age and formed more directly from magmatic systems much closer to the surface.

On the spread of the European catfish (Silurus glanis) in the Iberian Peninsula: first record in the Llobregat river basin

The first record of the European catfish (Silurus glanis L. 1758) introduced to the Llobregat river basin (NE Spain) is reported. We captured one individual of this silurid fish species (of a total of 541 fish) in La Baells reservoir on 30 August 2006. Given the low catchability of this fish species, the popularity among some anglers, and old rumours on this introduction, we hypothesize that this species has been present in the reservoir since a few years ago, despite we did not capture it in two previous surveys. The illegal introduction of this and other exotic species to other Iberian river basins should be prevented by the Spanish administration

Análise estratigráfica dos sedimentos eo/mesodevonianos da porção ocidental da Bacia do Amazonas sob a ótica da estratigrafia de seqüências no interior cratônico

O trabalho foi desenvolvido com a finalidade de verificação da aplicabilidade dos conceitos da moderna Estratigrafia de Seqüências no interior cratônico e a possibilidade do refinamento cronoestratigráfico da seção eo/mesodevoniana da Bacia do Amazonas. O autor utilizou as seguintes ferramentas disponíveis para a interpretação e elaboração de um modelo geológico para a seção sedimentar estudada: a) a análise da Paleogeografia, do Paleomagnetismo e da Paleoecologia, através do estudo da Tectônica e do Clima atuantes no Eo/mesodevoniano, no Supercontinente Gondwana, retratadas em reconstituições do mundo devoniano e apoiada em extensiva consulta bibliográfica e em correlação com os conteúdos faunístico, icnológico e litológico da seção que compõe o intervalo pesquisado, com o auxílio de testemunhos, amostras de calha e afloramentos, b) o estabelecimento de superfícies-chave da Estratigrafia de Seqüências, definidas com o apoio de perfis elétrico-radioativos, notadamente o perfil de raios-gama, c) a Cicloestratigrafia química com a utilização dos teores de carbono orgânico e o índice de hidrogênio, d) a Cicloestratigrafia orbital e climática, mediante a análise espectral do perfil de raios-gama da seção estudada e a definição do controle da sedimentação, influenciada pela excentricidade curta da órbita terrestre, em ciclos dentro da banda de freqüências de Milankovitch. O encadeamento dessas análises levou o autor a montar um arcabouço cronoestratigráfico para o Eo/mesodevoniano da porção ocidental da Bacia do Amazonas. Para tanto, foram consideradas a hierarquização das unidades, a definição dos tratos de sistemas deposicionais, limites de seqüências e outras superfícies-chave estratigráficas, e a duração temporal dos eventos. Além disso, são discutidas as possíveis causas principais da evolução tectono-estratigráfica da seção estudada e sua associação com a curva de variação do nível do mar devoniano. Realizou-se ainda, tentativamente, a correlação com outras bacias intracratônicas gondwânicas através da comparação do conteúdo faunístico, da xvii paleoclimatologia, da tectônica, da análise da variação da curva do nível do mar devoniano, da posição geográfica e da relação com o Pólo Sul devoniano, que serviram de base para a compreensão do evento relacionado à passagem do Givetiano ao Frasniano, nessas bacias. Como contribuições principais o autor aponta a aplicabilidade da Estratigrafia de Seqüências no interior cratônico e a possibilidade de refinamento cronoestratigráfico em pelo menos uma ordem de grandeza (10 6 anos para 10 5 anos) com a utilização da metodologia da Cicloestratigrafia orbital.

Estruturação do grupo Serra Grande região de Santana do Acaraú- CE e a reativação do lineamento Sobral Pedro II, integração com dados geofísicos

The study area is located in the NW portion of the Ceará state nearby the city of Santana do Acaraú. Geologically it lies along the Sobral-Pedro II lineament which limits the domains of Ceará Central and Noroeste do Ceará, both belonging to the Borborema Province.The object of study was a NE trending 30km long siliciclastic body (sandstone and conglomerate) bounded by transcurrent dextral faults. The sediments are correlated to the Ipú Formation (Serra Grande Group) from the Parnaiba basin, which age is thought to be Siluro-Devonian. Existing structural data shown that bedding has higher but variable dips (70-45) near the borders faults and much lower to subhorizontal inward the body. The brittle deformation was related to a reactivation, in lower crustal level, of the Sobral-Pedro II lineament (Destro (1987, 1999; Galvão, 2002).The study presented here was focused in applying geophysicals methods (gravimetry and seismic) to determine the geometry of the sandstone/conglomeratic body and together with the structural data, to propose a model to explain its deformation. The residual anomalies maps indicate the presence of two main graben-like structures. The sedimentary pile width was estimated from 2D gravimetric models to be about 500-600 meters. The 3D gravimetric model stressed the two maximum width regions where a good correlation is observed between the isopach geometry and the centripetal strike/dip pattern displayed by the sediments bedding. Two main directions (N-S and E-W) of block moving are interpreted from the distribution pattern of the maximum width regions of the sedimentary rock

Conchostráceos (Spinicaudata, Crustacea) do grupo Bauru (cetáceo superior, Bacia Bauru): taxonomia, paleoecologia e paleogeografia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análises estatística multivariada e filogenética dos dipnoiformes brasileiros. Comparações bióticas com o Gondwana ocidental

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)