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Nautiloidea svrchnokřídových epikontinentálních moří Evropy / Nautiloidea of Upper Cretaceous epicontinental seas in EuropeFrank, Jiří January 2014 (has links)
The post-Triassic Nautiloidea are not as popular theme within fossils cephalopods research as for example ammonites. They are not very abundant in the fossil records except some rare localities and areas, their morphology is quite conservative and due to the usually poor preservation, their determination and assigning to the species even to genera level is often complicated. Exceptional are taxa with very specific morphology and short stratigraphic and endemic occurrence, which are even suitable for biostratigraphic interpretations. Problematic is also the often poor taxonomical representation of the type material and revision of many taxa is needed. Still nautilids are often represented by reasonable amount in the paleontological collections of natural history museums due to the long history of fossils collecting. Also the scientific literature has been dedicating at least some space to this group since 19 century. The aim of this study is to create an overview about the post- Triassic, especially Upper Cretaceous nautiolidea in the European region of epicontinental seas and prepare a good basement for extensive study of this group. Due to this aim the study is primarily focused on determination of morphological features and also problematic with their interpretation according to the variable...
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Registro fóssil de podocarpaceae na ilha Rei George e a sua relação com os eventos paleoclimáticos e paleoambientaisFontes, Daiana January 2008 (has links)
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Previous issue date: 2008 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A composição e a diversidade dos representantes de Podocarpaceae nas tafofloras da ilha Rei George, norte da Península Antártica, atestam a importância deste grupo de coníferas nesta região no início do Cenozóico, após uma longa história evolutiva e uma origem igualmente ligada às altas latitudes do sul. O registro fóssil demonstra uma adaptabilidade e capacidade para conquistar novas áreas, diferentemente das outras famílias modernas de gimnospermas austrais, provavelmente devido à dispersão zoocórica e a variedade de formas e hábitos que ainda hoje mantém e que garantiram sua sobrevivência em praticamente todas as faixas de temperatura e gradientes altitudinais. Sete formas relacionadas a esta família foram descritas e se caracterizam pelos dois tipos principais de ramos, ainda hoje existentes. O primeiro deles caracterizado por folhas bifacialmente aplainadas, pequenas e mais ou menos adpressas, representados por duas espécies de Lepidothamnus sp., por Halocarpus sp. e Dacrycarpus sp. O outro grupo, com folhas grandes, com disposição bilateralmente aplainada e com uma veia média destacada, está representado por formas dos gêneros Saxegothaea e Podocarpus, para o qual uma nova espécie é pela primeira vez comunicada. Os macrorrestos estão preservados como impressões e carbonizações em dois dos principais locais da ilha que expõem as litologias durante o verão, o Monte Wawel, na baía do Almirantado, e o Morro dos Fósseis, na península Fildes. Representam sucessões vulcânicas e vulcanoclásticas, englobadas em duas unidades litoestratigráficas distintas, mas provavelmente correlacionáveis, as formações Fossil Hill e Vièville Glacier. Os níveis fossilíferos são compostos por grãos de origem vulcânica, retrabalhados ou não, que atestam sua afinidade com ambientes tectonicamente perturbados e com áreas baixas, de solos rejuvenescidos, onde havia condições para a formação de pequenos lagos e deltas durante as fases de erupções. O levantamento e comparação com outras paleofloras austrais e as idades radiométricas disponíveis permitiram propor uma idade Eoceno Médio para os diferentes níveis onde as podocarpáceas estão presentes e a vigência de um clima temperado úmido que, de modo relativamente rápido, dá lugar a evidências de queda nas temperaturas. A análise dos comparativos modernos sugere que compunham uma flora única, mista e diversificada, que reúne elementos com hábitos e adaptações distintas, se desenvolvendo em diferentes gradientes altitudinais, mais uma evidência em apoio à presença de áreas altas (vulcões?) e costeiras. Quando comparada aos modernos biomas, a paleoflora da ilha Rei George também exibe uma mescla de elementos, unindo hoje os que estão distribuídos nos dois extremos do Hemisfério Sul (América e Australásia), em grande parte endêmicos, e que vivem em lugares submetidos a baixas temperaturas. Assim ao mesmo tempo em que apóia condições climáticas semelhantes para o norte da Península Antártica durante o Eoceno, evidencia o importante papel que as terras do Gondwana e sua separação tiveram, sobre a moderna distribuição disjunta dos representantes desta família. / The composition and diversity of the Podocarpaceae representatives in the fossil plant assemblages of King George Island, north of Antarctic Peninsula, indicates their importance in that region during the Early Cenozoic, after a long evolutive history linked, since its origin, to the high southern latitudes. The fossil record attest an adaptability and capacity to conquer new areas that have no comparatives in other austral conifers, probably due to their seed dispersion by distinct groups of animals and the diverse forms and habits that their modern relatives still maintain. It guarantees their survival until today and their adaptation in nearly all latitudinal and altitudinal gradients. Seven distinct forms related to this family were described, characterized by two main kinds of leaf shoots. Those with scale and short leaf, bifacial flattened shoots are represented by two species of Lepidothamnus and by Halocarpus, Microcachrys and Dacrycarpus. The other one, with bilaterally flattened and big size leaves, with a sharp midrib, was associated with Saxegothaea and a species of Podocarpus, wich was for the first time described in the island taphofloras. The macrofossils are preserved by impressions and charcoalified materials, in the two main areas of the island where the lithologies are exposed in summer seasons, the Mount Wawel, at Admiralty Bay, and the Fossil Hill, at Fildes Peninsula. Represents what was included in two probably correlative lithostratigraphic units established in previous geological works, the Vièville Glacier and Fossil Hill formations. The fossil levels are composed mainly by volcanic grains, sometimes with signals of reworking by shallow lakes and deltas and confirm an environment and deposition linked to moments of active volcanism and inter-eruption phases. The comparisons with other fossil floras from the Antarctic Peninsula and Circum-Antarctic areas, and the radiometric ages indicates a probable lower mid-Eocene age, and wet and temperate climatic conditions, which deteriorates along the succession. The nearest modern relatives of the fossil taxa preserved in the taphofloras suggests also an unique, mixed and diversified vegetation, joining elements with distinct habits and that lives today in distinct altitudinal gradients, provides further evidence in support of the presence of high (volcanoes?) and coastal areas. The King George Island paleoflora flora also comprises a mixture of endemic, eastern Gondwana and South American elements, which reflect its position close to a major floristic boundary. At the same time confirms the microthermic conditions of climate in the north of Antarctic Peninsula at the Eocene times and the important role of the Gondwana drift apart, and the derivate climatic changes, in the modern disjunct distribution of the family.
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Prise en compte de l'histoire géologique des structures dans la création de modèles numériques 3D compatibles / Taking into account the evolution of geological structures in the creation of compatible 3D numerical modelsLaurent, Gautier 02 April 2013 (has links)
La modélisation des structures géologiques est une étape cruciale de la construction de géomodèles. Elles conditionnent la répartition spatiale des propriétés du sous-sol et la connexion des différents volumes rocheux qui le constituent. Cependant, les données disponibles s'avèrent incomplètes et incertaines. A cela s'ajoute une incertitude sur les phénomènes géologiques ayant conduit à la formation des structures modélisées. De multiples interprétations sont donc généralement possibles. Les méthodes classiques de modélisation des structures reposent principalement sur une approche géométrique, statique et déterministe. En d'autres termes, l'approche consiste à déterminer la meilleure représentation possible des structures en se fondant sur des critères qui portent principalement sur la géométrie actuelle des structures, comme la minimisation de leur courbure, et sur leur compatibilité avec les données dans leur état actuel. L'histoire tectonique des structures n'est prise en compte que de manière indirecte par le modélisateur et la compatibilité cinématique et mécanique du modèle structural reste complexe à évaluer. Cette thèse explore différentes méthodes de modélisations permettant de mieux prendre en compte l'histoire tectonique des structures. Trois approches complémentaires sont développées. La première propose un opérateur cinématique représentant les déplacements associés aux failles. Il tire son originalité du système de coordonnées curvilinéaires utilisé pour décrire l'espace de la faille et de l'intégration progressive des déplacements permettant de contrôler leur évolution. La seconde approche propose un outil de déformation pseudo-mécanique permettant l'édition interactive des modèles structuraux et la simulation approchée de l'histoire tectonique qui leur est associée. Il repose sur un algorithme de déformation original, basé sur des éléments rigides, issu du domaine de l'infographie. Enfin, une troisième approche permet de répercuter l'historique de déformation sur le système de coordonnées utilisé pour la simulation des propriétés du sous-sol. Nous montrons comment ce système peut être construit grâce à la restauration des structures. Cette approche permet de modéliser les propriétés du sous-sol en s'appuyant sur des paléodistances compatibles avec l'ensemble des hypothèses structurales, cinématiques et mécaniques établies lors de la construction de l'histoire tectonique du géomodèle. Ces différentes approches ouvrent des portes prometteuses dans la prise en compte des aspects historiques, cinématiques et mécanique dans la modélisation des structures et des propriétés du sous-sol. Elles s'attachent à accroître la compatibilité des géomodèles et à simplifier la paramétrisation des déformations géologiques afin de faciliter la résolution de problèmes structuraux par des approches inverses / The main approaches to the modelling of geological structures are mainly geometrical, static and deterministic. In other terms, their geometry and connections are determined by applying criteria based on the compatibility with available data in their current state. The evolution of the geological structures is only integrated indirectly by the modeller and the kinematical and mechanical compatibility of the produced models remain difficult to assess. This thesis explores different methods which aim at better including the evolution of geological structures in the modelling process. Three complementary approaches are developed. First, a kinematical fault operator based on a 3D curvilinear fault frame is presented. It aims at progressively deforming the structures surrounding faults. The second approach is based on a pseudo-mechanical deformation tool inspired form computer graphics, based on rigid elements. It is used to interactively editing the structures and approximately simulate their deformation history. The last proposal is to compute the paleo-geographical coordinates from the restoration of geological structures. This way, the heterogeneities are characterised based on paleo-geographic distances which are compatible with the structural, kinematical and mechanical hypotheses specified when building the geological model. These different contributions open numerous perspectives to better take into account the evolution of the geological structures when modelling the subsurface and its heterogeneities. They help us to increase the compatibility of geomodels and simplify the parameterization of geological deformation to facilitate the characterisation of geological structures by inverse approaches
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Evolução sedimentar da Formação Rio do Rasto na região centro-sul do Estado de Santa Catarina / Sedimentary evolution of Rio do Rasto Formation (Permian-Triassic of the Paraná basin) in the central-south portion of Santa Catarina State, BrazilWarren, Lucas Verissimo 31 March 2006 (has links)
A porção sul do supercontinente Gondwana, durante o intervalo de tempo compreendido entre o Neocarbonífero e o Eotriássico, é marcada por importantes eventos de ordem tectônica e sedimentar. Neste contexto, um ciclo de subsidência se desenvolveu acompanhando os movimentos da então denominada Orogenia Sanrafaélica, resposta da colisão do terreno Patagônico com a borda SW do Gondwana. O soerguimento das margens deste supercontinente propiciou a formação de um grande corpo d´água confinado, ou apresentando diminutas conexões oceânicas. A geração de novo e volumoso espaço de acomodamento possibilitou a acumulação de uma seqüência transgressivo-regressiva entre o neopermiano e o eotriássico da Bacia do Paraná. O caráter predominantemente progradacional da porção superior desta seqüência, culminou com a completa colmatação do corpo d´água, propiciando o desenvolvimento de sistemas deposicionais continentais ao final deste ciclo. Os sedimentos da Formação Rio do Rasto, objeto da presente dissertação, se inserem neste contexto e são caracteristicamente representativos dos depósitos de trato de mar alto desenvolvidos nos estágios terminais da evolução desta seqüência de segunda ordem, denominada ?Gondwana I? (Milani, 1997). A área de estudo da presente dissertação compreende a porção centro-sul e leste do Estado de Santa Catarina, englobando a carta topográfica do município de Lages e as serras do Rio do Rasto, Rio do Sul e Espigão, localizadas nas escarpas a leste do estado homônimo. Nesta região ocorrem rochas das unidades paleozóicas e mesozóicas na Bacia do Paraná, litoestratigraficamente pertencentes aos Grupos Tubarão, Guatá, Passa Dois e São Bento. A Formação Rio do Rasto caracteriza-se por aflorar muito bem na área estudada, possibilitando o levantamento de seções contínuas e o estudo detalhado de afloramentos sob a ótica da análise de fácies, elementos arquiteturais e análise de paleocorrentes. A Formação Rio do Rasto encontra-se encerrada por contatos de caráter transicional com as formações Teresina na base e Pirambóia no topo. É composta, litoestratigraficamente, pelos membros Serrinha e Morro Pelado, que perfazem, na área de estudo, espessuras máximas da ordem de 250 metros. De modo geral, a unidade caracterizase por seu caráter predominantemente progradacional, com a tendência de aumento de estratos de arenitos para o topo. Os sedimentos da porção basal da unidade, pertencentes ao Membro Serrinha, caracterizam-se pela presença de fácies heterolíticas, pelíticas e de coloração acinzentada, depositadas em condições de costa-afora. A ocorrência de elementos arquiteturais constituídos por arenitos com estrutura hummocky, swalley e laminação cruzada por onda é indicativa da deposição a partir de eventos pontuados de elevado grau energético. Concentrações fossilíferas compostas por dentes, escamas e coprólitos de peixes, aqui classificadas com bone beds, apresentam afinidades tafonômicas com depósitos originados por tempestades. Intercaladas a esta associação, ocasionalmente ocorrem camadas métricas lenticulares e sigmoidais de arenitos finos, interpretadas como depósitos de barras de desembocadura deltaica. Para o topo da unidade ocorre a mudança na coloração das fácies pelíticas cinzas para termos de coloração avermelhada e roxa, bem como o predomínio de elementos arquiteturais tipicamente deltaicos, como depósitos de baías, canais interdistributários e vi lobos de rompimento de diques marginais. Elementos arquiteturais eólicos ocorrem intercalados nas porções superiores do Membro Morro Pelado. A ocorrência de associações de fácies depositadas em diferentes posições fisiográficas dentro de um contexto deltaico pode ser expressa na alternância de elementos arquiteturais distais e proximais em todos os exemplos estudados. Esta particularidade pode ser parcialmente explicada pelo caráter fortemente autocíclico esperado em sistemas deposicionais deltaicos, o que propicia a migração constante dos canais, e conseqüentemente das áreas de baía interdistributários e desembocadura. Além da autociclicidade, outro fator determinante na construção do padrão arquitetural observado, é a variação das taxas de subida do nível relativo do mar. Ressalta-se que, inserido em um contexto maior de trato de mar alto, a tendência de desaceleração de subida do nível do mar é sempre esperada. Esta variação, ocorrendo em freqüência relativamente alta, propicia a variação na geração de espaço de acomodamento, determinando aumentos ou diminuições na razão entre aporte sedimentar e abertura de espaço. Desta maneira, quando a razão apresenta valores positivos desenvolve-se um padrão sedimentar progradacional, com conseqüente regressão da linha de costa. Valores negativos, materializados em maior taxa de geração de espaço de acomodação, em relação ao aporte sedimentar, propicia a formação de sucessões de arquitetura retrogradacional e transgressão da linha de costa. Conforme o sistema deltaico progradava, o mar interior ia sendo paulatinamente colmatado, resultando na tendência geral de diminuição do espaço de acomodação de sedimentos. Nas porções inferiores da Formação Rio do Rasto (Membro Serrinha) este fato se expressa na diminuição dos depósitos de tempestade para o topo, ou seja, com o decréscimo volumétrico e em área do corpo d´água, diminui a possibilidade da atuação de ondas de tempestade e conseqüentemente, o retrabalhamento dos sedimentos deltaicos por estes. Os depósitos de tempestades praticamente não ocorrem nas porções superiores da unidade (Membro Morro Pelado), onde, portanto, estão preservadas camadas tabulares lateralmente contínuas, associadas ao desenvolvimento de fluxos hiperpicnais nas porções frontais das barras de desembocadura deltaicas. O preenchimento por sedimentos e a diminuição volumétrica do corpo aquoso não implicaram na compartimentação deste em diversos lagos de menor extensão. O padrão de empilhamento de elementos arquiteturais associado à escassez de níveis contínuos de paleossolo e superfícies erosivas regionais bem marcadas permitem refutar esta hipótese. Dada a continuidade das associações de fácies e recorrência de elementos arquiteturais, em toda a área estudada na presente dissertação, o Sistema Deltaico do Rio do Rasto possivelmente apresentava tamanho em área compatível com a escala de dezenas de milhares de quilômetros quadrados. Dados de paleocorrentes sugerem progradação do edifício deltaico de SE para NW. A ocorrência no segundo terço estratigráfico da unidade, de elementos arquiteturais eólicos intercalados, pode ser considerada uma evidência da transição para o sistema desértico Pirambóia. Os dados de paleoventos indicam tendência de migração do sistema de dunas para WNW, em direção concordante à estimada para a migração do Sistema Deltaico Rio do Rasto. A tendência de continentalização da bacia culmina com os depósitos da Formação Pirambóia, estratigraficamente localizada acima e em contato transicional com a Formação Rio do Rasto. / The south portion of the supercontinent Gondwana, during the time period between the neocarboniferous and the eotriassic, is marked by important events in tectonic and sedimentary order. In this context, a subsidence cycle developed itself along the movements of the then-nominated Sanrafaelic Orogeny, the result of the collision between the Patagonic terrains with the southwestern border of Gondwana. The uplift of this supercontinent?s margins made possible the creation of a large confined body of water, or displaying small oceanic connections. The development of a new, large space of accommodation generated, then, the accumulation of a transgressive-regressive sequence between the neopermian and the eotriassic of Paraná Basin. The mainly progradational character of the upper portion of this sequence culminated with the complete filling of the body of water, allowing the development of depositional continental systems at the end of this cycle. The sediments of the Rio do Rasto formation, object of the present dissertation, are inserted in this context and characteristically representative of the highstand system tract deposits that developed in the terminal stages of this second-order sequence, named ?Gondwana I?(Milani, 1997). The study area of the present dissertation comprehends the central-southern and the eastern portion of the state of Santa Catarina, including the topographic chart of the Lages province e the Rio do Rasto, Rio do Sul and Espigão sierras, located in the eastern cliffs of the homonymous state. In this region, rocks of the paleozoic and mesozoic units of Paraná?s Basin occur, which lithostratigraphically are part of the Tubarão, Guatá, Passa Dois and São Bento groups. The Rio do Rasto formation is notable for an outcropping in the studied area, making possible the uplifting of the continued sessions and the detailed study of the outcrops under the view of the facies analysis, architectural elements and the paleocurrents analysis.The Rio do Rasto formation is surrounded in contacts of transitional character with the the Teresina formation, at the base, and Pirambóia formation at the top. It is composed, lithostratigraphically, by the Serrinha and Morro Pelado members, that present, in the studied área, maximum thickness of 250 meters. Generally, the unit is marked by its predominant progradational character, with the tendency of sandstones strata increasing to the top. The sediments of the base portion of the unit, from the Serrinha member, are characterized by the presence of heterolithic, pelithic and gray-colored facies, deposited in offshore conditions. The occurrence of sandstone-based architectural elements with hummocky structure, swalley and cross-lamination by waves, is indicative of the deposition from high energetic degree events. Fossil concentrations composed of teeth, scales e fish coprolites, here classified as bone beds, present tafonomic similarities with the stormgenerated deposits. Interbedded to this association, lenticular and sigmoidal metric layers from thin sandstones occasionally occur, interpreted as deltaic mouth bars deposits. At the top of the unit, the change of the gray pelithic facies coloration to red and purple tonalities occurs, as well as the predominance of typically deltaic architectural elements, such as basin deposits, interdistributary channels e crevasse splay lobes. Eolian architectural elements occur interbedded on the upper portions of the Morro Pelado member. The occurrence of associations of deposited facies in different physiographic positions inside a deltaic context, can be expressed in the alternation of nearshore and offshore architectural elements in all of the studied examples. This particularity can be partially explained by the strong auto cyclic character expected in deltaic depositional systems, which allows the constant migration of the channels, and consequentially of the interdistributary bay areas and deltaic mouths. Aside from the autocyclicity, another determinant factor in the interbedding of architectural elements is the variation of relative sea level rates, inside a larger context of highstand system tract, where the tendency of deceleration in the sea level rising speed is expected. This variation, occurring in relatively high frequency, makes possible the variation in the accommodation space generation, determining increasing and decreasing on the reason between sedimentary in-fill and the generation of acomodation space. Hence, when the reason presents positive values, a sedimentary progradational character is developed, with consequent regression of the coast line. Negative values, expressed in a bigger rate of accommodation space generation, compared to the sedimental aport, make possible the formation of retrogradational architecture successions and a transgression of the coast line. As the deltaic system progrates, the inner sea is gradually filled, materializing the general tendence of a shrinking in the accommodation space of sediments. In the lower portions of the Rio do Rasto formatiom (Serrinha member), this fact is expressed in the smaller presence of storm deposits to the top, which means that with the reduction of the body of water area, the possibility of reworking of the deltaic sediments through certain high energetic level events is diminished. The storm deposits do not occur on the upper portions of the unit (Morro Pelado member), where, as a result, the horizontally continuous tabular layers are preserved, associated to the development of hyperpicnal fluxes on the frontal portions of the deltaic mouth bars. The filling by sediments and the diminishing in volume of the water body do not result in its compartmentation in several smaller lakes. The pattern of the vertical succession of architectural elements associated to the shortage of continuous levels of paleosoils and marked regional erosive surfaces, allows one to deny this hypothesis. Given the continuity of the deltaic elements in all of the area studied in the present dissertation, the deltaic system of Rio do Rasto possibly presented a size, in area, compatible with the scale of thousands of square kilometers. Data of paleocurrents suggest progradation of the deltaic building from S/SE to N/NW. The occurrence of eolian architectural elements interbedded with sub aquatically deposited sediments, on the second stratigraphic third of the unit, can be considered an evidence of transition to the Pirambóia desert system. The paleoevents data indicate a migration tendence of the dune system to the NW, in a similar direction to the estimated for the Rio do Rasto deltaic system migration. The continentalization tendence of the basin results in the eolic deposits of the Pirambóia formation, stratigraphically located above and in transitional contact with the Rio do Rasto formation.
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Sedimentology and Stratigraphy of the Middle Jurassic Preuss Sandstonein Northern Utah and Eastern IdahoCook, Preston Scott 01 June 2016 (has links)
The purpose of this study is to analyze the sedimentology and stratigraphy of the Middle Jurassic Preuss Sandstone and re-evaluate past sedimentological interpretations. The Preuss is located in northern Utah, western Wyoming and eastern Idaho and is stratigraphically equivalent to the Entrada Sandstone, which is Callovian in age (Dossett et al., 2014). This study is the first attempt at 1) a sequence stratigraphic framework, 2) a petroleum system analysis and 3) an extraterrestrial analog study for the Preuss. This study frames the Preuss within three broad facies groups: marine, coastal and terrestrial. The marine group includes the open marine and restricted marine facies with associated subfacies, the coastal group includes coastal sabkha and associated subfacies, and the terrestrial group includes alluvial, inland sabkha and eolian facies with associated subfacies. Three sections in northern Utah and one section in eastern Idaho compromise the focus of this study. The three Utah sections were measured and described, and samples were collected from two Utah sections and the Idaho section. The Preuss Sandstone was deposited in an asymmetrical retroarc basin, consequently the Preuss thickens from the east towards west-central Utah and the Jurassic Elko highlands. The deposits are mostly terrestrial, which is in accord with recent sedimentological interpretations, but at odds with the old paradigm, which postulates that the Entrada and Preuss were largely tidal in origin. There are marine transgressions within the trough of the retroarc basin, and the transgressions affect terrestrial sedimentary patterns. During marine incurstions, alluvium shed off the highlands is confined west of the seaway, and does not prograde east of the trough until all the available accommodation is filled. The Preuss was deposited during a complete third-order sequence-stratigraphic cycle that lies within the Lower Zuni II second-order lowstand. The Preuss Sandstone can be used as an outcrop analog for ancient and modern environments both here on Earth and on other planetary bodies. The petroliferous Norphlet Formation along the U.S. Gulf Coast was deposited in an environment very similar to the Preuss, but the Waltherian succession of facies might be slightly different. Likewise, the facies present in the Preuss are analogous to modern arid environments, such as the Persian Gulf. Furthermore, the alluvial, sabkha, eolian and shallow marine facies of the Preuss are highly similar to facies observed in ancient Martian environments and modern environments on Saturn's moon, Titan.
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Els caròfits de les fàcies continentals i transicionals del Garumnià basal (Cretaci superior) del Pirineu OrientalVillalba Breva, Sheila 27 March 2012 (has links)
Aquesta tesi té com a objectiu fonamental la caracterització taxonòmica, biostratigràfica i paleoecològica de les associacions de caròfits de les fàcies lacustres i transicionals del Garumnià basal (Cretaci superior) de les Conques de Vallcebre, Coll de Nargó, Tremp i Àger. L’altre objectiu d’aquesta tesi és la caracterització tafonòmica i paleoecològica de les restes fòssils de plantes vasculars productores dels lignits garumnians.
La flora de caròfits del Garumnià basal està constituïda per girogonits de Feistiella malladae, Peckichara cancellata, P. sertulata, Microchara cristata, M. parazensis, Platychara caudata, P. turbinata i Dughiella obtusa, i utricles de Clavator brachycerus. Pel que fa als òrgans vegetatius les calcàries garumnianes son molt riques en tal•lus de grans dimensions de Charaxis sp. associats a Peckichara sp., i de tal•lus més gràcils de Clavatoraxis microcharophorus Villalba-Breva et Martín-Closas 2011, portadors de Microchara sp. També és freqüent la presència de Munieria grambastii associada a vegades a Clavator brachycerus.
Des del punt de vista biostratigràfic, les associacions de caròfits de les conques d’Àger i Vallcebre pertanyen a la biozona de caròfits Peckichara cancellata (Campanià superior - Maastrichtià inferior basal), mentre que les associacions de caròfits de les conques de Coll de Nargó i Tremp pertanyen a la biozona Septorella ultima (Maastrichtià inferior). En base a l’estudi estratigràfic i sedimentològic i l’anàlisi de microfàcies s’ha determinat que la sedimentació a la Conca d’Àger està formada majoritàriament per calcàries lacustres organitzades en centenars de seqüències de somització, que van des de fàcies lacustres profundes, passant per ambients marginals, ben il•luminats dominats per herbeis de caràcies, fins a fàcies de vora de llac dominades per herbeis de clavatoràcies. A les conques de Vallcebre, Coll de Nargó i Tremp, la sedimentació del Garumnià basal està organitzada en diversos cicles, els quals comencen amb dipòsits salabrosos formats per margues amb mol•luscs eurihalins a la base, seguits per lignits i calcàries d’ambients salabrosos dominades per porocaràcies, i calcàries d’aigua dolça amb caràcies i clavatoràcies. Les diferències en el registre sedimentari i la flora de caròfits mostren que les conques sud pirinenques presentaven una polaritat de fàcies sud-nord durant l’inici de la sedimentació continental del Cretaci superior, i que aquesta continentalització va començar al sud i desprès va continuar al nord, d’est a oest.
L’estudi de la macroflora del Garumnià basal de les conques de Vallcebre, Coll de Nargó i Tremp indica que la comunitat vegetal dels aiguamolls del Maastrichtià inferior estava dominada per la conífera queirolepidiàcia Frenelopsis, que va ser la planta productora de la matèria orgànica precursora del lignit. Associada a aquestes coníferes hi havia la palmera Sabalites longirhachis, i en alguns casos altres angiospermes d’aiguamoll, representades per les seves llavors, especialment Bergacarpon viladricii Marmi, Gomez, Villalba-Breva et Martín-Closas 2012. Altres plantes vasculars significatives encara que menys abundants eren les falgueres, cicadals i pandanals. / This thesis aims to characterize the taxonomy, biostratigraphy and palaeoecology of charophyte assemblages of lacustrine and transitional facies from the basal Garumnian (Late Cretaceous) of the Vallcebre, Coll de Nargó, Tremp and Àger basins. The other objective of this study is the taphonomic and palaeoecological characterization of the precursory vascular plants of the Garumnian lignite.
The charophyte flora of the basal Garumnian consists of gyrogonites of Feistiella malladae, Peckichara cancellata, P. sertulata, Microchara cristata, M. parazensis, Platychara caudata, P. turbinata and Dughiella obtusa, and utricles of Clavator brachycerus. Regarding the vegetative organs, Garumnian limestones are rich in large thalli of Charaxis sp. associated to Peckichara sp., and smaller thalli of Clavatoraxis microcharophorus Villalba-Breva et Martín-Closas 2011, with attached Microchara sp. Also Munieria grambastii thalli are abundant, associated sometimes with Clavator brachycerus.
From a biostratigraphic point of view, charophyte assemblages of Vallcebre and Àger basins belong to the Peckichara cancellata biozone (Late Campanian – Earliest Maastrichtian), while charophyte assemblages of Coll de Nargó and Tremp basins belong to the Septorella ultima biozone (Early Maastrichtian). Based on the sedimentological and stratigraphic studies and microfacies analyses, the sedimentation in the Àger Basin is organised into hundreds of small order sedimentary cycles corresponding to lacustrine infilling sequences, ranging from deep lacustrine facies, through marginal environments dominated by characean meadows, to lakeshore facies dominated by clavatorecean meadows. In the Vallcebre, Coll de Nargó and Tremp basins, the deposits of the basal Garumnian are organized into small number of cycles that show a transition from brackish deposits formed by marls with euryhaline molluscs, lignites and limestones with porocharaceans, to lacustrine limestones with characeans and clavatoraceans. The differences in the sedimentary record and in the charophyte flora show that the Southern Pyrenean Basin displayed a south to north shift of facies during the onset of the Upper Cretaceous continental sedimentation and that this continentalisation began in the south and then continued to north, from east to west.
The study of megafossil plant remains from the basal Garumnian of the Vallcebre, Coll de Nargó and Tremp basins indicates that the cheirolepidiacean conifer Frenelopsis was the main component of the wetlands vegetation associated with Sabalites longirhachis palms, and in some cases with other angiosperms, such as the plant bearing Bergacarpon viladricii Marmi, Gomez, Villalba-Breva et Martín-Closas 2012, probably a commelinid.
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Stratigraphy, paleogeography and tectonic evolution of early Paleozoic to Triassic pericratonic strata in the northern Kootenay Arc, southeastern Canadian Cordillera, British ColumbiaKraft, Jamie L Unknown Date
No description available.
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Sedimentology, stratigraphy, and provenance of the upper Purcell Supergroup, southeastern British Columbia, Canada: implications for syn-depositional tectonism, basin models, and paleogeographic reconstructionsGardner, David William 29 April 2008 (has links)
This thesis reports eight measured sections and >400 new detrital zircon U-Pb SHRIMP-II ages from the Mesoproterozoic (~1.4 Ga) upper Purcell Supergroup of southeastern British Columbia, Canada. The goal of my study is to constrain the depositional, tectonic and paleogeographic setting of the upper Purcell Supergroup.
Stratigraphic sections across the Purcell Anticlinorium, constructed from measured sections, reveal three syn-depositional growth faults: (1) paleo-Hall Lake, (2) paleo-Larchwood Lake, and (3) paleo-Moyie. Stratigraphic sections were combined into a fence diagram, revealing a large north-northeast trending graben bound to the east by the paleo-Larchwood Lake fault and to the west by the paleo-Hall Lake fault.
Five samples were collected for detrital zircon analysis along the eastern extent of exposed Purcell strata; one sample was collected from the western limit of strata. All samples are characterized by subordinate numbers of detrital zircons that yield Paleoproterozoic and Archean ages. Detrital zircon ages from the Sheppard Formation are dominated by 1500, 1700, 1750, and 1850 Ma grains. The overlying Gateway Formation is dominated by 1400-1450, 1700, 1850, and 1900 Ma zircon grains. The overlying Phillips, Roosville (east), and Mount Nelson formations are dominated by detrital zircon ages between 1375-1450 Ma and 1650-1800 Ma. Detrital zircon ages from the Roosville Formation (west) are dominated by 1500-1625 Ma grains.
Based on the margin perpendicular orientation of the long axis of syn-depositional grabens relative to Laurentia, and on the presence of syn-depositional aged zircons through the entire sedimentary succession, we interpret the upper Purcell Supergroup to have been deposited in a transpressional pull-apart basin setting, adjacent to a convergent/translational plate margin bound to the west by terranes now located in northeastern Australia.
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Evolução sedimentar da Formação Rio do Rasto na região centro-sul do Estado de Santa Catarina / Sedimentary evolution of Rio do Rasto Formation (Permian-Triassic of the Paraná basin) in the central-south portion of Santa Catarina State, BrazilLucas Verissimo Warren 31 March 2006 (has links)
A porção sul do supercontinente Gondwana, durante o intervalo de tempo compreendido entre o Neocarbonífero e o Eotriássico, é marcada por importantes eventos de ordem tectônica e sedimentar. Neste contexto, um ciclo de subsidência se desenvolveu acompanhando os movimentos da então denominada Orogenia Sanrafaélica, resposta da colisão do terreno Patagônico com a borda SW do Gondwana. O soerguimento das margens deste supercontinente propiciou a formação de um grande corpo d´água confinado, ou apresentando diminutas conexões oceânicas. A geração de novo e volumoso espaço de acomodamento possibilitou a acumulação de uma seqüência transgressivo-regressiva entre o neopermiano e o eotriássico da Bacia do Paraná. O caráter predominantemente progradacional da porção superior desta seqüência, culminou com a completa colmatação do corpo d´água, propiciando o desenvolvimento de sistemas deposicionais continentais ao final deste ciclo. Os sedimentos da Formação Rio do Rasto, objeto da presente dissertação, se inserem neste contexto e são caracteristicamente representativos dos depósitos de trato de mar alto desenvolvidos nos estágios terminais da evolução desta seqüência de segunda ordem, denominada ?Gondwana I? (Milani, 1997). A área de estudo da presente dissertação compreende a porção centro-sul e leste do Estado de Santa Catarina, englobando a carta topográfica do município de Lages e as serras do Rio do Rasto, Rio do Sul e Espigão, localizadas nas escarpas a leste do estado homônimo. Nesta região ocorrem rochas das unidades paleozóicas e mesozóicas na Bacia do Paraná, litoestratigraficamente pertencentes aos Grupos Tubarão, Guatá, Passa Dois e São Bento. A Formação Rio do Rasto caracteriza-se por aflorar muito bem na área estudada, possibilitando o levantamento de seções contínuas e o estudo detalhado de afloramentos sob a ótica da análise de fácies, elementos arquiteturais e análise de paleocorrentes. A Formação Rio do Rasto encontra-se encerrada por contatos de caráter transicional com as formações Teresina na base e Pirambóia no topo. É composta, litoestratigraficamente, pelos membros Serrinha e Morro Pelado, que perfazem, na área de estudo, espessuras máximas da ordem de 250 metros. De modo geral, a unidade caracterizase por seu caráter predominantemente progradacional, com a tendência de aumento de estratos de arenitos para o topo. Os sedimentos da porção basal da unidade, pertencentes ao Membro Serrinha, caracterizam-se pela presença de fácies heterolíticas, pelíticas e de coloração acinzentada, depositadas em condições de costa-afora. A ocorrência de elementos arquiteturais constituídos por arenitos com estrutura hummocky, swalley e laminação cruzada por onda é indicativa da deposição a partir de eventos pontuados de elevado grau energético. Concentrações fossilíferas compostas por dentes, escamas e coprólitos de peixes, aqui classificadas com bone beds, apresentam afinidades tafonômicas com depósitos originados por tempestades. Intercaladas a esta associação, ocasionalmente ocorrem camadas métricas lenticulares e sigmoidais de arenitos finos, interpretadas como depósitos de barras de desembocadura deltaica. Para o topo da unidade ocorre a mudança na coloração das fácies pelíticas cinzas para termos de coloração avermelhada e roxa, bem como o predomínio de elementos arquiteturais tipicamente deltaicos, como depósitos de baías, canais interdistributários e vi lobos de rompimento de diques marginais. Elementos arquiteturais eólicos ocorrem intercalados nas porções superiores do Membro Morro Pelado. A ocorrência de associações de fácies depositadas em diferentes posições fisiográficas dentro de um contexto deltaico pode ser expressa na alternância de elementos arquiteturais distais e proximais em todos os exemplos estudados. Esta particularidade pode ser parcialmente explicada pelo caráter fortemente autocíclico esperado em sistemas deposicionais deltaicos, o que propicia a migração constante dos canais, e conseqüentemente das áreas de baía interdistributários e desembocadura. Além da autociclicidade, outro fator determinante na construção do padrão arquitetural observado, é a variação das taxas de subida do nível relativo do mar. Ressalta-se que, inserido em um contexto maior de trato de mar alto, a tendência de desaceleração de subida do nível do mar é sempre esperada. Esta variação, ocorrendo em freqüência relativamente alta, propicia a variação na geração de espaço de acomodamento, determinando aumentos ou diminuições na razão entre aporte sedimentar e abertura de espaço. Desta maneira, quando a razão apresenta valores positivos desenvolve-se um padrão sedimentar progradacional, com conseqüente regressão da linha de costa. Valores negativos, materializados em maior taxa de geração de espaço de acomodação, em relação ao aporte sedimentar, propicia a formação de sucessões de arquitetura retrogradacional e transgressão da linha de costa. Conforme o sistema deltaico progradava, o mar interior ia sendo paulatinamente colmatado, resultando na tendência geral de diminuição do espaço de acomodação de sedimentos. Nas porções inferiores da Formação Rio do Rasto (Membro Serrinha) este fato se expressa na diminuição dos depósitos de tempestade para o topo, ou seja, com o decréscimo volumétrico e em área do corpo d´água, diminui a possibilidade da atuação de ondas de tempestade e conseqüentemente, o retrabalhamento dos sedimentos deltaicos por estes. Os depósitos de tempestades praticamente não ocorrem nas porções superiores da unidade (Membro Morro Pelado), onde, portanto, estão preservadas camadas tabulares lateralmente contínuas, associadas ao desenvolvimento de fluxos hiperpicnais nas porções frontais das barras de desembocadura deltaicas. O preenchimento por sedimentos e a diminuição volumétrica do corpo aquoso não implicaram na compartimentação deste em diversos lagos de menor extensão. O padrão de empilhamento de elementos arquiteturais associado à escassez de níveis contínuos de paleossolo e superfícies erosivas regionais bem marcadas permitem refutar esta hipótese. Dada a continuidade das associações de fácies e recorrência de elementos arquiteturais, em toda a área estudada na presente dissertação, o Sistema Deltaico do Rio do Rasto possivelmente apresentava tamanho em área compatível com a escala de dezenas de milhares de quilômetros quadrados. Dados de paleocorrentes sugerem progradação do edifício deltaico de SE para NW. A ocorrência no segundo terço estratigráfico da unidade, de elementos arquiteturais eólicos intercalados, pode ser considerada uma evidência da transição para o sistema desértico Pirambóia. Os dados de paleoventos indicam tendência de migração do sistema de dunas para WNW, em direção concordante à estimada para a migração do Sistema Deltaico Rio do Rasto. A tendência de continentalização da bacia culmina com os depósitos da Formação Pirambóia, estratigraficamente localizada acima e em contato transicional com a Formação Rio do Rasto. / The south portion of the supercontinent Gondwana, during the time period between the neocarboniferous and the eotriassic, is marked by important events in tectonic and sedimentary order. In this context, a subsidence cycle developed itself along the movements of the then-nominated Sanrafaelic Orogeny, the result of the collision between the Patagonic terrains with the southwestern border of Gondwana. The uplift of this supercontinent?s margins made possible the creation of a large confined body of water, or displaying small oceanic connections. The development of a new, large space of accommodation generated, then, the accumulation of a transgressive-regressive sequence between the neopermian and the eotriassic of Paraná Basin. The mainly progradational character of the upper portion of this sequence culminated with the complete filling of the body of water, allowing the development of depositional continental systems at the end of this cycle. The sediments of the Rio do Rasto formation, object of the present dissertation, are inserted in this context and characteristically representative of the highstand system tract deposits that developed in the terminal stages of this second-order sequence, named ?Gondwana I?(Milani, 1997). The study area of the present dissertation comprehends the central-southern and the eastern portion of the state of Santa Catarina, including the topographic chart of the Lages province e the Rio do Rasto, Rio do Sul and Espigão sierras, located in the eastern cliffs of the homonymous state. In this region, rocks of the paleozoic and mesozoic units of Paraná?s Basin occur, which lithostratigraphically are part of the Tubarão, Guatá, Passa Dois and São Bento groups. The Rio do Rasto formation is notable for an outcropping in the studied area, making possible the uplifting of the continued sessions and the detailed study of the outcrops under the view of the facies analysis, architectural elements and the paleocurrents analysis.The Rio do Rasto formation is surrounded in contacts of transitional character with the the Teresina formation, at the base, and Pirambóia formation at the top. It is composed, lithostratigraphically, by the Serrinha and Morro Pelado members, that present, in the studied área, maximum thickness of 250 meters. Generally, the unit is marked by its predominant progradational character, with the tendency of sandstones strata increasing to the top. The sediments of the base portion of the unit, from the Serrinha member, are characterized by the presence of heterolithic, pelithic and gray-colored facies, deposited in offshore conditions. The occurrence of sandstone-based architectural elements with hummocky structure, swalley and cross-lamination by waves, is indicative of the deposition from high energetic degree events. Fossil concentrations composed of teeth, scales e fish coprolites, here classified as bone beds, present tafonomic similarities with the stormgenerated deposits. Interbedded to this association, lenticular and sigmoidal metric layers from thin sandstones occasionally occur, interpreted as deltaic mouth bars deposits. At the top of the unit, the change of the gray pelithic facies coloration to red and purple tonalities occurs, as well as the predominance of typically deltaic architectural elements, such as basin deposits, interdistributary channels e crevasse splay lobes. Eolian architectural elements occur interbedded on the upper portions of the Morro Pelado member. The occurrence of associations of deposited facies in different physiographic positions inside a deltaic context, can be expressed in the alternation of nearshore and offshore architectural elements in all of the studied examples. This particularity can be partially explained by the strong auto cyclic character expected in deltaic depositional systems, which allows the constant migration of the channels, and consequentially of the interdistributary bay areas and deltaic mouths. Aside from the autocyclicity, another determinant factor in the interbedding of architectural elements is the variation of relative sea level rates, inside a larger context of highstand system tract, where the tendency of deceleration in the sea level rising speed is expected. This variation, occurring in relatively high frequency, makes possible the variation in the accommodation space generation, determining increasing and decreasing on the reason between sedimentary in-fill and the generation of acomodation space. Hence, when the reason presents positive values, a sedimentary progradational character is developed, with consequent regression of the coast line. Negative values, expressed in a bigger rate of accommodation space generation, compared to the sedimental aport, make possible the formation of retrogradational architecture successions and a transgression of the coast line. As the deltaic system progrates, the inner sea is gradually filled, materializing the general tendence of a shrinking in the accommodation space of sediments. In the lower portions of the Rio do Rasto formatiom (Serrinha member), this fact is expressed in the smaller presence of storm deposits to the top, which means that with the reduction of the body of water area, the possibility of reworking of the deltaic sediments through certain high energetic level events is diminished. The storm deposits do not occur on the upper portions of the unit (Morro Pelado member), where, as a result, the horizontally continuous tabular layers are preserved, associated to the development of hyperpicnal fluxes on the frontal portions of the deltaic mouth bars. The filling by sediments and the diminishing in volume of the water body do not result in its compartmentation in several smaller lakes. The pattern of the vertical succession of architectural elements associated to the shortage of continuous levels of paleosoils and marked regional erosive surfaces, allows one to deny this hypothesis. Given the continuity of the deltaic elements in all of the area studied in the present dissertation, the deltaic system of Rio do Rasto possibly presented a size, in area, compatible with the scale of thousands of square kilometers. Data of paleocurrents suggest progradation of the deltaic building from S/SE to N/NW. The occurrence of eolian architectural elements interbedded with sub aquatically deposited sediments, on the second stratigraphic third of the unit, can be considered an evidence of transition to the Pirambóia desert system. The paleoevents data indicate a migration tendence of the dune system to the NW, in a similar direction to the estimated for the Rio do Rasto deltaic system migration. The continentalization tendence of the basin results in the eolic deposits of the Pirambóia formation, stratigraphically located above and in transitional contact with the Rio do Rasto formation.
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Les séries de l'Ordovicien moyen et supérieur de l'Anti-Atlas oriental (Maroc) : stratigraphie, sédimentologie et paléogéographie des systèmes de plate-forme silico-clastique / Middle and upper Ordovician series of Eastern Anti-Atlas (Morocco) : stratigraphy, sedimentology and paleogeography of siliciclastic platformMeddour, Amira 05 September 2016 (has links)
L’étude de l’Ordovicien de l’Anti-Atlas oriental s’intègre dans un vaste projet celui de l’étude de la plate-forme nord-gondwanienne qui se caractérise par une sédimentation essentiellement silico-clastique avec une polarité globale qui est Sud-Nord. Cette étude, basée sur les principes de la stratigraphie séquentielle et de la sédimentologie, met en évidence l’existence de deux systèmes de dépôts sur la marge nord-ouest de la plate-forme nord-gondwanienne. A l’Ordovicien moyen et supérieur préglaciaire, à l’emplacement de l’Anti-Atlas oriental, coexistent un système deltaïque (lato sensu) et un système de plate-forme dominée par l’action de la houle et des tempêtes. Ces deux systèmes de dépôts ont une certaine répartition spatiale et temporelle. Le système deltaïque domine le nord-est de l’Anti-Atlas oriental où il prend naissance à l’Est du Tafilalt. Ce système deltaïque est à dominance fluviale, il est actif lors des périodes de régression. Pendant les maximums de régression, il incise le haut du plateau continental en créant d’importantes structures érosives dont le remplissage se fait par des faciès de haute énergie à composante unidirectionnelle. Le système de haute énergie influencé par l’action de la houle et des tempêtes domine le secteur sud de l’Anti-Atlas oriental et se répand au nord au cours des périodes transgressives. La sédimentation durant l’Ordovicien préglaciaire sur la marge nord-ouest du Gondwana a un contrôle tectonique et eustatique avec une polarité des systèmes, dans le Tafilalt-Maïder qui diffère de celle de la plate-forme nord-gondwanienne et est Nord Est-Sud-Ouest. Le profil de dépôt est quasi plat où les clinoformes sont de faible amplitudes et se dessinent à l’intérieur des séquences de 3ème ordre. Le Darriwillien se caractérise par des une subsidence différentielle entre le domaine nord et le domaine sud en raison d’une tectonique active. Alors que, le Sandbien-Katien montre un taux de subsidence faible (x 10m/Ma) en adéquation avec un contexte intracratonique. L’Hirnantien dans le Tafilalt, décrit comme étant discontinu voir absent, est très bien développé il se caractérise par la mise en place d’une sédimentation mixte gréso-carbonaté à bryozoaires de type littoral et ce à l’extrémité oriental de l’Anti-Atlas et d’une épaisse série conglomératique (conglomérat d’Amessoui et d’Imzizoui) et flyschoïde qui peut atteindre les 500m dans le Tafilalt. / The Ordovician Anti-Atlas study is part of a larger project of comprehension the sedimentary system of the north Gondwana platform. This sedimentary area is characterized by essentially terrigenous sediments that come from the south from de West African Craton. This study based on sequence stratigraphy and sedimentology principles highlights two systems juxtaposed during the preglacial Ordovician period (before hirnantian). These two deposits systems have a spatial and temporal distribution. One deltaic occurs on north-eastern Tafilalt (east Anti-Atlas) and widespread during regressive periods. The second is storm dominate system which is developed in the south-western part of eastern Anti-Atlas and transgressive periods. The deltaic system is river dominant, it incise the continental shelf by creating a significant erosive structure whose filling is done by high energy facies unidirectional component. During the Ordovician, the sedimentation was controlled by tectonic and eustatic variation. The polarity of the system in the Tafilalt-Maïder is different from that of the northern Gondwana platform and it is given North East- South West. The Darriwilian characterized by differential subsidence, between the north and the south of the oriental Anti-Atlas, due to active tectonics, while, Sandbian-Katian show a low subsidence rates (x10m/Ma) in the line of intracratonic basin. The Hirnantian, in Tafilalt, is largely well developed and characterized by huge conglomeratic series, flysch deposits and Bryozoan limestone at the northeastern.
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