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Late Mesozoic extensional tectonics in south China / La tectonique extensive à la fin du Mésozoïque en Chine du sudJi, Wenbin 17 October 2014 (has links)
Les structures extensives d'âge Mésozoïque tardif (Crétacé) sont très répandues en Eurasie orientale, depuis la Transbaïkalie en Russie jusqu'à l'intérieur de la Chine du Sud. Elles constituent la plus grande province de distension crustale dans le monde. Cette thèse a sélectionné des structures développées dans trois endroits différents du bloc de Chine du sud en utilisant les méthodes de la géologie structurale, de l'anisotropie de la susceptibilité magnétique et de la géochronologie (U-Pb sur zircon et titanite, U-Th-Pb sur monazite et Ar-Ar sur micas et amphiboles). L'expression des structures extensives diffère selon les endroits étudiés: (1) la ceinture orogénique de HP/UHP Tongbai-Dabie, le long de la bordure nord du bloc de Chine du sud a été remaniée par au Crétacé par la formation d'un antiforme ou d'un dôme métamorphique extensif. Contemporaine de la migmatisation et du magmatisme syntectonique, le régime extensif a commencé à environ 145 Ma et s'est approché de son point culminant vers 130 Ma. Ce qui a été interprété comme le résultat de la suppression de la racine orogénique. Localement, un nouvel épisode de distension vers 110-90 Ma a également été enregistré; (2) le batholite de Dayunshan-Mufushan intrudif dans l'orogène Neoproterozoic Jiangnan se compose de deux phases d'intrusions granitiques d'âge Jurassique (ca. 150 Ma) et Crétacé inférieur (ca. 132 Ma). Le pluton le plus récent s'est mis en place dans un contexte d'extension NW-SE correspondant au processus amincissement crustal du Crétacé inférieur, avec une faille de détachement développée le long de sa bordure ouest; (3) l'anticlinal de Huangling dans le craton du Yangtze est un pli asymétrique d'axe N-S formé entre le Jurassique et le Crétacé inférieur. Sur les deux flancs, la couverture sédimentaire a participé à une série de plis d'effondrement de vergence opposée et de glissements banc-sur-banc des couches. Les exemples étudiés ci-dessus représentent une série de structures d'extension d'âge Crétacé développées dans différents niveaux structuraux: exhumation de croûte inférieure et moyenne de accommodée par un fort étirement, mise en place syntectonique de plutons granitiques avec étirement limité, déformation de la couverture sédimentaire sous une faible extension. Ils indiquent que la Chine du Sud a également participé au régime extensif bien connu en Chine du Nord. Ces résultats apportent des données nouvelles de première main permettant de discuter le cadre tectonique et géodynamiques spatio-temporel du régime extensif du Crétacé sur la marge orientale de l'Eurasie. / Late Mesozoic extensional structures are widespread in eastern Eurasia (from Transbaikalia region in Russia to inland South China). They constitute the largest crustal extensional province in the world. This thesis selected extensional structures developed in three different tectonic settings in the South China block. Detailed studies including structural geology, anisotropy of magnetic susceptibility and geochronology (zircon and titanite U-Pb, monazite U-Th-Pb, and mica Ar-Ar) were conducted. The expression of these extensional structures is not the same for each area: (1) the Tongbai-Dabie HP/UHP orogenic belt along the northern edge of the South China block was reworked by Cretaceous extensional antiform or metamorphic core complex. Coeval with migmatization and syntectonic magmatism, the extensional regime started at ca. 145 Ma, and approached its climax at ca. 130 Ma that was signaled by removal of the orogenic root. Locally, a late (110-90 Ma) extensional event was also recorded; (2) the Dayunshan-Mufushan batholith intruding the Neoproterozoic Jiangnan orogen is composed of two phases of granitic intrusions with Late Jurassic (ca. 150 Ma) and Early Cretaceous (ca. 132 Ma) ages, respectively. The late pluton emplaced under a NW-SE extensional setting corresponding to the Early Cretaceous crustal thinning process, with a detachment fault developed along its western margin; (3) the Huangling anticline within the Yangtze craton is a nearly N-S striking asymmetric dome formed between the Late Jurassic and Early Cretaceous. The sedimentary cover on the two flanks was involved in a series of oppositely-directed collapse folding and layer-parallel slipping. These examples of Cretaceous extensional structures in different tectonic levels (exhumation of middle-lower crust by strong stretching, syn-tectonic emplacement of granitic pluton with limited stretching, deformation of sedimentary cover under a weak extension) indicates that South China also was involved into the regional extensional regime coeval with the destruction of the North China craton. These results provide first-hand new structural evidence for further discussing the temporal-spatial framework and geodynamic setting of the Cretaceous extensional tectonics on the eastern margin of Eurasia.
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Vertebrados fósseis do estado de Goiás, com ênfase em sua fauna de amniotas, compreendida entre o período permiano e a época pleistoceno /Paulo, Pedro Oliveira. January 2009 (has links)
Orientador: Reinaldo José Bertini / Banca: Maria Rita Caetano Chang / Banca: Gisele Mendes Lessa del Giúdice / Resumo: Embora possua significativas áreas com depósitos sedimentares, o Estado de Goiás apresenta-se quase inexplorado quanto aos vertebrados fósseis. O principal objetivo desta investigação foi reunir, em um único trabalho, todas as ocorrências de paleovertebrados de Goiás, compreendidos entre o Período Permiano e a Época Pleistoceno, a partir das referências bibliográficas disponíveis e dos materiais depositados em algumas coleções brasileiras. No Estado de Goiás ocorrem significativas áreas de exposição de estratos paleozóicos, da Bacia do Paraná. Destacam-se as formações Irati e Corumbataí, cujas idades correspondem respectivamente aos Permianos Inferior e Médio. Para a Formação Irati têm sido reportadas ocorrências de restos de mesossauros, desde os primeiros levantamentos geológicos empreendidos em Goiás, em meados dos anos 1930. Para a Formação Corumbataí, os restos coletados em Goiás limitam-se a fragmentos de escamas e dentes de peixes, ainda inéditos. No Estado de Goiás ocorrem também significativas áreas de exposição de afloramentos das unidades componentes da Bacia Bauru, de idade Cretáceo Superior. Correspondem às formações Adamantina e Marília, aflorantes em amplas áreas ao Sul do estado. Destas unidades foram anotadas ocorrências de restos dinossaurianos na região Sudoeste, especialmente no Membro Echaporã da Formação Marília. Coberturas superficiais pleistocênicas são encontradas em áreas correspondentes aos interflúvios dos principais rios. Algumas destas forneceram significativas quantidades de restos atribuíveis a megafauna pleistocênica, especialmente em localidades nunca antes reportadas, como Goiânia e Niquelândia. As cavernas de Goiás forneceram expressiva quantidade de materiais pleistocênicos / holocênicos, de grande interesse ao estudo da diversidade das comunidades... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Despite significant areas with sedimentary strata, and great possibility for prospections of fossil remains, the Goias State is still barely explored. The main objective of this work is to gather, in one contribution, all occurrences of paleovertebrates of the Goiás State, from Permian Period to Pleistocene Epoch. The informations for this compilation are based on available literature and Brazilians museums and collections. In the Goiás State there are considerable areas with exposition of Paleozoic strata, being related to the Paraná Basin. The Irati and Corumbataí formations are respectively related to Lower and Middle Permian. For the Irati Formation there has been reported the occurrence of mesosaurs, since the first geological studies performed in Goias, during the 1930s. For the Corumbataí Formation, the remains collected in the state are restricted to fragments of fishes teeth and scales, still not published. In the Goiás State there are substantial areas of the Bauru Basin, from the Upper Cretaceous. They are associated to the Adamantina and Marília formations, geological unities occurrying on areas situated Southern Goiás State. From these units there have been reported the occurrence of dinosaur remains, especially in the Echaporã Member from the Marília Formation. Pleistocenic deposits are commonly found in areas corresponding to ridges between the most important rivers. Some of these regions provide relevant amounts of remains, associated the Giant Pleistocene Fauna, especially in localities never reported before, just as Goiânia and Niquelândia. Goiás State caves also provided an abundant amount of Pleistocenic / Holocenic remains, of great importance for the study of the diversity of vertebrates communities during this chronological transition. Among the most important catalogued families are Didelphidae, Dasypodidae, Phylostomidae, Natalidae, Vespertilionidae... (Complete abstract click electronic access below) / Mestre
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Descrição de Novos Materiais Referentes à Tapejaridae (pterosauria, Pterodactyloidea) da Formação Romualdo (Bacia do Araripe, Ceará, Brasil)Aires, Alex Sandro Schiller January 2013 (has links)
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Previous issue date: 2013 / O clado Pterosauria é constituído por répteis alados que viveram durante a Era
Mesozóica (entre 215 a 65 milhões de anos antes do presente) e habitaram diversas regiões do
planeta. Pertencente a este clado, o g rupo Tapejaridae é caracterizado principalmente pela
peculiar morfologia rostral e por não possuir dentes. O estudo filogenético de tapejarídeos do
nordeste do Brasil é baseado na sua maioria em elementos do crânio, devido à escassez de esqueletos
pós-cranianos. Este estudo descreve morfologicamente e classifica, através de análise filogenética,
um novo espécime atribuído à Tapejaridae, proveniente da Formação Romualdo (Grupo
Santana, Bacia do Araripe, CE). O material compreende dez vértebras articuladas (as três
últimas cervicais e também as sete primeiras dorsais que se fusionam, formando o notário), o
escapulocoracóide direito, a escápula e o coracóide esquerdos, um fragmento de esterno, o
úmero direito parcialmente preservado, um fragmento da 4a falange do dígito alar, a porção
distal do femur direito e a porção proximal da tíbia/fíbula . Foram geradas três árvores na
análise filogenética, sendo que em duas delas AMNH 22567 foi posicionado dentro de
Thalassodrominae . Contudo, na outra árvore o espécime se pocisionou como Tapejaridae basal.
Mesmo assim, sua assignação como Thalassodrominae se justifica pela presença de três foramens
posicionados dorsal e lateralmente ao canal neural nas vértebras cervicais; presença de notário e
presença de um forâmen pneumático ventral na porção proximal do úmero. Estes materiais são os
mais completos elementos pós-cranianos deste grupo de pterossauros descritos até o
momento. Com relação à paleobiogeografia, Tapejaridae aparenta ter surgido no oeste da
Eurásia durante o Neojurássico, migrando para sudoeste e dando origem as formas
eocretácicas da Bacia do Araripe. / Pterosauria is a clade composed of flying reptiles that lived during the Mesozoic Era
(215 to 65 million of years before present) and inhabited various regions of the world. Within
this large clade, Tapejaridae is mainly characterized by peculiar rostral morphology and
absence of tooths. The phylogenetical studies of the tapejarids from northeastern Brazil are
mainly based on cranial elements, due to shortage of postcranial skeletons. This study
described and classified through a phylogenetical analysis, a new specimen ascribed to
Tapejaridae from Romualdo Formation (Araripe Basin, CE), housed at the American Museum
of Natural History (under the acronym AMNH 22567) and comments on the
paleobiogeography of this group. The material comprises ten articulated vertebrae (three
cervicals and seven subsequent dorsals fusioned, ones forming the notarium), a right
scapulocoracoid, a left scapula and a left coracoid, a partial sternum, a right humerus, a
fragment of 4th phalanx of the alar digit, a distal fragment of right femur and a fragment of
the proximal portion of the right tibia/fibula. The phylogenetical analysis generated three
different topologies, two of them placing AMNH 22567 within Thalassodrominae (subclade
of Tapejaridae). In the other one, the specimen was placed in a basal position within
Tapejaridae. Nonetheless, the presence of three foramina lateral and dorsal to the neural canal
of the cervical vertebrae, the presence of a notarium and presence of a pneumatic foramen on
the ventral side of the proximal portion of the humerus allow its assignation as a
Thalassodrominae indet. The specimen comprises the more complete postcranial material for
this subfamily described so far. Regarding the paleobiogeography of Tapejaridae, it appears to
originated in western Eurásia during the Neojurassic and later migrated to southwest and
irradiated to new Eocretacic forms in Araripe Basin.
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Nova proposta de arcabouço estratigráfico e evolução tectono-sedimentar do registro cretácico da Bacia dos Parecis, centro oeste do BrasilRubert, Rogério Roque January 2017 (has links)
A Bacia dos Parecis é uma bacia intracratônica, com uma área de 500.000 km2 na região Centro-Oeste do Brasil. Ocupa a porção sul-sudeste do Cráton Amazônico, tendo este como maior parte de seu embasamento. Acumula mais de 6.000 m de sedimentos, relacionados ao Paleozoico, Mesozoico e Cenozoico. O registro mesozoico inclui unidades sedimentares e vulcânicas. O registro cretácico da Bacia dos Parecis consiste em duas sequências sedimentares com assinaturas deposicionais distintas. Essas sequências são fisicamente descontínuas e relacionadas a diferentes depocentros, nas porções leste e oeste do Arco da Serra Formosa, ou seja, sub-bacias Juruena e Alto Xingu. Isto gera controvérsias em termos de correlação regional, posicionamento estratigráfico e correta subdivisão das sequências. Com base em afloramentos e testemunhos de sondagem foi possível a reconstituição do registro a partir das associações de fácies. Estas associações juntamente com o reconhecimento regional de superfícies e relações estratigráficas permitiu a identificação de uma assinatura deposicional diferencial para cada sequência. Na sub-bacia Juruena foram depositadas sequências predominantemente clásticas, fluviais e eólicas. Na sub-bacia do Alto Xingu, na base foram identificadas fácies de natureza química e clástica e no topo, sedimentação clástica. A reconstituição da evolução da bacia no Mesozoico e a contextualização das unidades cretácicas foram efetuadas levando-se em conta os registros do tectonismo, do magmatismo e da sedimentação na região. A evolução da bacia no Mesozoico teve início no Triássico Superior e Jurássico Inferior com vulcanismo e sedimentação, sucedido de soerguimento e erosão até o Cretáceo Inferior, quando ocorreram magmatismos básico e alcalino. A partir do Cretáceo Superior, com início da fase compressiva da Orogenia Andina e abertura do Oceano Atlântico, desenvolveu-se tectonismo e a sedimentação na sub-bacia Juruena no Cenomaniano. Porém, na sub-bacia Alto Xingu esta ocorre a partir do Coniaciano. A análise do registro fossilífero e as relações com unidades adjacentes indicam uma idade entre Cenomaniano-Turoniano para a sequência da sub-bacia Juruena e Coniaciano-Santoniano para a sequência da sub-bacia Alto Xingu. Assim, foi proposta uma nova unidade litoestratigráfica para esta última, denominada de Formação Rio Tapirapé. A atuação da tectônica na geração de subsidência diferenciada para cada sub-bacia ocasionou a geração de diferentes assinaturas deposicionais. Na sub-bacia Juruena a taxa de sedimentação superior à taxa de subsidência é perceptível, gerando sequências clásticas de alta energia. Na sub-bacia Alto Xingu, a taxa de subsidência é superior à taxa de sedimentação, com um sistema lacustre transgressivo nas fases iniciais. Ao final em ambas as sub-bacias prevalecem sistemas sedimentares fluviais e deltaicos enquanto a taxa de subsidência é reduzida. A reconstituição paleoambiental da sequência cretácica da sub-bacia Alto Xingu identificou uma sedimentação clasto-química de fundo e borda de lago na base. Na porção superior ocorre uma progradação com ambientes de prodelta, frente deltaica e uma planície deltaica com planície fluvial e deposição eólica. O posicionamento cronoestratigráfico Coniaciano-Santoniano baseou-se em fósseis de vertebrados e ostracodes que tem crono-correlatos regionais na Formação Adamantina (Grupo Bauru) e Formação Capacete (Bacia Sanfranciscana) e ainda na Formação Bajo de Carpa (Grupo Neuquén, na Argentina). / The Parecis Basin is an intracratonic basin, covering a huge area of 500.000 km2 in center-west portion of Brazil. The Amazonian Craton constitutes the most part of its basement. In this basin, there are an accumulation of more than 6,000 m of sediments, related to Paleozoic, Mesozoic and Cenozoic ages. The Mesozoic record includes sedimentary and volcanic units. The cretaceous record of the Parecis Basin is represented by two sedimentary sequences characterized by distinct depositional signatures. These sequences are physically discontinuous, and related to different depocenters located in the east and west of Serra Formosa Arch, namely Juruena and Alto Xingu sub-basins. So, this distribution is controversy in terms of regional correlation, stratigraphic positioning and correct subdivision of the sequences. Based on outcrops and cores information it was possible the reconstruction of the record from the facies association, which together with regional surface recognition and stratigraphic relations allowed the identification of a differential depositional signature for each sequence. In the Juruena sub-basin, predominantly clastic fluvial and aeolian sequences were deposited. In the Alto Xingu sub-basin the base is marked by facies of lacustrine chemical and clastic nature but top, clastic sedimentation of a fluvio-deltaic system is recognized. The reconstruction of the mesozoic evolution of the basin and contextualization of the Cretaceous units were carried out taking into account records of tectonism, magmatism and sedimentation in the region. The basin evolution in Mesozoic age start in Upper Triassic to Lower Jurassic period where occurred volcanism and sedimentation, followed by uplift and erosion until the Lower Cretaceous, when as occurred basic and alkaline magmatism. From the Upper Cretaceous, with the beginning of the compressive phase of Andean Orogeny and opening of the Atlantic Ocean, tectonism and sedimentation were developed in Juruena Sub-basin in the Cenomanian and Alto Xingu Sub-basin from Coniacian. The relation of the fossiliferous record with adjacent units allows to assign one related age between Cenomanian-Turonian to Juruena sub-basin sequence. But the Coniacian-Santonian to Alto Xingu sub-basin is being proposed an new lithostratigraphic. unit named Rio Tapirapé Formation results from this recognition. The tectonism is the main event in the generation of differentiated subsidence to each sub-basin and the differential depositional signatures. In the Juruena sub-basin the sedimentation rate over the subsidence rate is perceptible, and a clastic high energy sequence is deposited. In the Alto Xingu sub-basin, the subsidence rate is higher than the sedimentation rate, with a transgressive lacustrine system with chemical sedimentation in the initial phases. At the end of the process, in both sub-basins, fluvial and deltaic sedimentary systems prevail while the subsidence rate decreases. The paleoambiental reconstruction of Alto Xingu sub-basin cretaceous sequence indicates a chemical and clastic sedimentation of bottom and shoreline lake, in a context of high initial subsidence and low sedimentation rate. As the subsidence process decreased, a deltaic progradation became dominant with deposition in a prodelta environment, deltaic front and deltaic plain interbedded with fluvial plain, and aeolian deposition. The Coniacian–Santonian chronostratigraphic positioning was based on vertebrate fossils and ostracods with regional chrono-correlates in the Adamantina Formation (Bauru Group), the Capacete Formation (Sanfranciscana Basin), and also in the Bajo de la Carpa Formation (Neuquén Group, in Argentina).
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Análise palinológica em folhelhos da Formação Morro do Chaves e implicações na evolução paleogeográfica da fase rifte da Bacia de Sergipe - AlagoasGarcia, Gustavo Gonçalves January 2016 (has links)
O processo de fragmentação do Continente Gondwana vem sendo gradativamente mais entendido a partir de estudos realizados nas bacias sedimentares situadas nas margens atlânticas atuais. Nesse contexto a Bacia de Sergipe-Alagoas torna-se relevante em decorrência da completude com que apresenta as sequências estratigráficas deposicionais registradas durante este processo, expostas em afloramento ou em subsuperfície, com importante significado no âmbito das pesquisas sobre rochas geradoras e reservatório de hidrocarbonetos. O presente trabalho tem como objetivo aprofundar a recuperação e o reconhecimento de conteúdos palinológicos em depósitos da Formação Morro do Chaves, Sub-bacia Alagoas, visando contribuir para a ampliação da base de dados micropaleontológicos da unidade e direcionado para o refinamento dos enfoques bioestratigráficos, paleoambientais e paleogeográficos relacionados com a sua origem. Como objetivo consequente busca-se o melhor entendimento sobre a evolução paleo-bio-geográfica da região, hoje ocupada por distintas bacias residuais no interior do nordeste do Brasil, durante os eventos iniciais de invasões marinhas sobre áreas antes continentais localizadas no interior do continente gondwanico, seja através da ruptura da crosta e oceanização propriamente dita, ou pela invasão de águas marinhas através de baixios intra-continentais, durante intervalos de elevação do nível do mar global (Mar de Thetis/Atlantico Central). A análise do material tem sua origem nos afloramentos da Formação Morro do Chaves, pertencente a Pedreira InterCement (ex-Cimpor/Atol), localizada no município de São Miguel dos Campos, Alagoas. Dezessete amostras de folhelhos foram coletadas na cava da pedreira, ao longo de 63 m de uma seção vertical principal para análises palinológicas. Além destas, 28 amostras de folhelhos coletadas em testemunhos de quatro furos (IC-1 a IC-4) perfurados na área da pedreira. Foram selecionadas duas amostras para análise do furo IC-1 (96,14 m de profundidade total), 10 do IC-2 (225,55 m), 14 do IC-3 (212,54 m) e duas do IC-4 (119,98 m). Um total de 11 táxons de palinomorfos foram identificados, cinco relativos a esporos, três a grãos de pólen gimnospérmicos, três a angiospermas, quatro de elementos algálicos (?Dinophyceae, Prasinophyceae e Clorophyceae), um ?palinoforamínfero e cinco esporos indeterminados de fungos. Com base na ocorrência da espécie Dicheiropollisetruscus, que compreende os andares Rio da Serra até Jiquiá Superior, em conjunto com outros dados paleontológicos e geológicos determina-se a idade Barremiana para o intervalo. A partir da associação palinológica reconhecese que estes corpos d’água estavam situados em uma planície, com plantas herbáceas, cercada por regiões montanhosas remotas, com vegetação rara de porte arbóreo. Em alguns níveis identificaram-se vesículas de algas pré-classificadas como possíveis algas da classe Prasinophyceae, cujo habitat possível é marinho, no entanto também há registros em ambientes de água doce ou salobra. A identificação preliminar dos espécimes de palinoforaminifero e de dinoflagelado corroboram com esta idéia, bem como a presença de organismos como Scenedesmus e Botryoccocus, organismos que toleram certa salinidade. Ratifica-se assim a probabilidade de influência marinha e/ou salobra no Cretáceo, no setor norte da Bacia de Sergipe-Alagoas, podendo aproximar a unidade ao modelo paleogeográfico que discute a entrada de águas Thetianas ao norte do continente Sul-Americano. / The fragmentation process of the Gondwana continent has been increasingly understood as a result of the studies held in the sedimentary basins located on the Atlantic’s current margins. Within this context, the Sergipe-Alagoas Basin becomes important as a result of the complementarity with which the depositional stratigraphic sequences recorded during this process are presented. Such sequences, exposed in outcrop or in subsurface, are of great deal for research studies in source-rocks and hydrocarbon reservoirs. The objective of the present work is to get a more detailed knowledge of the palynological content in Morro do Chaves Formation deposits, at Alagoas Sub-basin. It will allow an expansion of the micropaleontological database of the studied unit as well as a refinement of the biostratigraphic, paleoenvironmental and paleogeographic approaches related to its origin. Also, we search for a better understanding of the paleo-biogeographical region evolution, which is nowadays occupied by different residual basins in Brazil northeast interior, during the early events of marine ingressions over previous continental areas located inside the Gondwana continent, either through crust rupture and oceanization itself or due to the invasion of marine waters through intra-continental shallows during intervals of rising of the global sea levels (Tethys Sea / Center Atlantic). The analysis of the material has its origin in outcrops from the Morro do Chaves Formation belonging to the InterCement Quarry (former Cimpor/Atol), located in São Miguel dos Campos, Alagoas State. Seventeen samples were collected from shales in the quarry pit, along 63 m of the main vertical section for pollen analysis. Apart from these, 28 samples of shales were collected from the four drill-cores (IC-1 to IC-4) drilled in the quarry area. Two samples from the IC-1 drill-core (96.14 m total depth), ten from IC-2 (225.55 m), fourteen from IC-3 (212.54 m) and two from IC-4 (119.98 m) were selected for analysis. A total of eleven taxa of palynomorphs have been identified. Five are related to spores, three to gymnosperms pollen grains, three to angiosperms, four to algae elements (?Dinophyceae, Prasinophyceae, and Clorophyceae), one to a ?palinoforaminifera and five unidentified fungal spores. Based on the occurrence of Dicheiropollis etruscus species, comprising Rio da Serra to Upper Jiquiá Superior age, together with other paleontological and geological data, it is possible to determine the Barremian age for the studied interval. The pollen association shows that these water bodies were located on a plain, with herbaceous plants, surrounded by remote mountain regions, where arborous vegetation was rare. In some levels were identified algae vesicles pre-classified as possible algae from the Prasinophyceae class, most likely from marine environment. However there are also records of this algae class in fresh or brackish water environments. The preliminary identification of specimens of ?palinoforaminifera and dinoflagellate corroborate this idea as well as the presence of organisms such as Scenedesmus and Botryoccocus, organisms that tolerate a certain level of salinity. It is thus recognized the possible influence of marine and/or brackish waters in the Cretaceous, in the northern sector of the Sergipe-Alagoas Basin. Such conclusions allow an approach of the studied unit to the paleogeographic model that discusses the input of waters from the Tethys Sea at the north of the South American continent.
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Bioestratigrafia e paleoecologia de foraminíferos da Bacia de Barreirinhas, cretácio, margem equatorial brasileiraSilva, Cristiane Pakulski da January 2011 (has links)
O presente estudo integra informações bioestratigráficas e paleoecológicas obtidas através da análise de foraminíferos planctônicos e bentônicos recuperados dos sedimentos provenientes de cinco poços (1-MAS-1, 1-MAS-3A, 1-MAS-4A, 1-MAS-14 e 1-MAS-15) da Bacia de Barreirinhas, perfazendo um total de 127 amostras de calha preparadas e analisadas. Os sedimentos aqui analisados abrangem os andares Albiano superior ao Campaniano superior com registro geológico inserido nos grupos Caju (Albiano - Cenomaniano) e Humberto de Campos (Turoniano - Maastrichtiano). Através dos dados bioestratigráficos obtidos foi possível estabelecer sete biozonas de foraminíferos, de caráter local, com base na última ocorrência do táxon guia (LAD - Last Appereance Datum). O Albiano superior foi definido com base nas biozonas do foraminífero planctônico Ticinella primula Lauterbacher (1963) e foraminíferos bentônicos Lingulogavelinella albiensis Malapris (1965)-Gyroidina bandyi Trujillo (1960); o Cenomaniano inferior foi determinado através das biozonas do foraminífero planctônico Globigerinelloides bentonensis Morrow (1934) e foraminífero bentônico Coronorotalites aptiensis Bettenstaedt (1952); o Cenomaniano superior foi reconhecido através das biozonas do foraminífero planctônico Rotalipora appeninica Renz (1936) e foraminífero bentônico Gavelinella intermedia Berthelin (1880); o Campaniano superior foi determinado com base na biozona do foraminífero planctônico Heterohelix pulchra Brotzen (1936). Após a identificação da microfauna, foi possível reconhecer 108 espécies de foraminíferos pertencentes a cinco subordens: a Subordem Globigerinina, de foraminíferos planctônicos, é representada por 40 espécies e 15 gêneros; os foraminíferos bentônicos são compostos por 68 espécies e 48 gêneros, pertencentes as Subordens Rotaliina, Textulariina, Lagenina e Miliolina. Através da análise da assembléia de foraminíferos, foi possível traçar a CCD (Carbonate Compensation Depth - Profundidade de Compensação do Carbonato) nos poços e separá-los com base na profundidade em: distais (1-MAS-1 e 1-MAS-14) e proximais (1-MAS-3A, 1-MAS-4A e 1-MAS-15). Observou-se que a Bacia de Barreirinhas possui uma tendência geral transgressiva ao longo do Período Cretáceo, caracterizada por meio do influxo sedimentar através de variações climáticas, como o aquecimento global ocorrido neste período. Esta teoria é reforçada pela completa ausência de tecas calcárias, tanto de foraminíferos bentônicos, quanto planctônicos, associada à ocorrência exclusiva de bentônicos aglutinantes e silicosos (Reophax globosus) nos poços distais ao final do Período Cretáceo. Nos poços 1-MAS-3A, 1-MAS-4A e 1-MAS-15, a fauna de foraminíferos identificada apresenta adaptações morfológicas a condições de baixa oxigenação na coluna d'água, características normalmente observadas durante os Eventos Oceânicos Anóxicos (Oceanic Anoxic Event - OEA). Como exemplo destas adaptações morfológicas, foram identificadas três espécies pertencentes ao gênero Schakoina, que possui câmaras alongadas e a espécie Biticinella breggiensis, que possui câmaras bilobadas, sugerindo um aumento na produtividade primária, disponibilidade de nutrientes e paleoambientes depletados em oxigênio. Com base nestas informações foi possível identificar que um Evento Anóxico de caráter local tenha ocorrido durante o Albiano superior, registrado somente nos poços 1-MAS-3A e 1-MAS-4A, enquanto que o Evento Anóxico Global 2 foi registrado no poço 1-MAS-15. / This study integrates biostratigraphic and paleoecological information obtained through of planktonic and benthic foraminifera analysis from sediment recovered from five wells (1-MAS-1, 1-MAS-3A, 1-MAS-4A, 1-MAS-14 and 1-MAS-15) of Barreirinhas Basin, making a total of 127 samples prepared and analyzed. The sediments analyzed here cover the upper Albian to upper Campanian stages with geological record inserted in the Caju (Albian - Cenomanian) and Humberto de Campos (Turonian - Maastrichtian) groups. Through the biostratigraphic data obtained it was possible to establish seven foraminiferal biozones, of local character, based on the last occurrence of taxon guide (LAD - Last Appereance Datum). The upper Albian was defined based on planktonic foraminifera biozones of Ticinella primula Lauterbacher (1963) and benthic foraminifera Lingulogavelinella albiensis Malapris (1965)-Gyroidina Bandy Trujillo (1960); the lower Cenomanian was determined through the planktonic foraminifera biozones of Globigerinelloides bentonensis Morrow (1934) and benthic foraminifera Coronorotalites aptiensis Bettenstaedt (1952); the upper Cenomanian was recognized through the planktonic foraminifera biozones of Rotalipora appeninica Renz (1936) and benthic foraminifera Gavelinella intermedia Berthelin (1880); the upper Campanian was determined based on the planktonic foraminifera biozone Heterohelix pulchra Brotzen (1936). After the identification of microfauna, was possible to recognize 108 species of foraminifera belonging to five suborders: the Suborder Globigerinina, of planktonic foraminifera, is represented by 40 species and 15 genera; the benthic foraminifera are composed of 68 species and 48 genera, belonging to the suborders Rotaliina, Textulariina, Lagenina and Miliolina. Through analysis of foraminifera assemblage it was possible to trace the CCD (Carbonate Compensation Depth) in the wells and separate them based on depth in: distal (1-MAS-1 and 1-MAS-14) and proximal (1-MAS-3A, 1-MAS-4A and 1-MAS-15). It was noted that the Barreirinhas Basin has an overall transgression during the Cretaceous Period, characterized by sedimentary influx through weather changes, like global warming that occurred during this period. This theory is enhanced by the complete absence of calcareous tests, both of benthic as planktonic foraminifera associated with the exclusive occurrence of agglutinating and arenaceous benthic (Reophax globosus) in the distal wells of the end of Cretaceous Period. In the wells 1-MAS-3A, 1-MAS-4A and 1-MAS-15, the foraminifera fauna identified presents morphological adaptations to conditions of low oxygen in the water column, features typically seen during the Oceanic Anoxic Event (OEA's). As examples of these morphological adaptations, was identified three species of the Schakoina genera, which has elongated chambers and Biticinella breggiensis species, which has bilobeted chambers, suggesting an increase in the primary productivity, nutrient availability and paleoenvironments depleted in oxygen. Based on this information it was possible to identify a local character anoxic events occurred during the upper Albian, recorded only in a well 1-MAS-3A and 1-MAS-4A, while the global anoxic event 2 was recorded in a well 1-MAS-15.
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Gimnospermas eocretáceas da Formação Crato, bacia do Araripe, Nordeste do Brasil / Early Creatceous gymnosperms from the Crato Formation, Araripe Basin, Northeast BrazilSucerquia Rendon, Paula Andrea 19 January 2007 (has links)
A Formação Crato, localizada na bacia do Araripe, Nordeste do Brasil, contém um dos registros fossíferos vegetais mais importantes do Cretáceo Inferior. Estes fósseis apresentam excelente estado de preservação, no geral, com pouca fragmentação, órgãos em conexão e estruturas epidérmicas e anatômicas delicadamente substituídas por óxidos de ferro. Como acontecia globalmente, as gimnospermas eram o grupo vegetal dominante na paleoflora eocretácea da Formação Crato, ocorrendo na forma de Bennettitales, Coniferales e Gnetales. As Bennettitales foram um componente aparentemente raro, estando representado pelas espécies Otozamites sp. e Zamites sp. Dentre as Coniferales, encontram-se as famílias Araucariaceae e Cheirolepidiaceae, as Araucariaceae registradas nas espécies Araucarites vulcanoi Duarte e Araucarites kunzmanni sp. nov.; as Cheirolepidiaceae, o grupo mais diverso, estão representadas pelas espécies Brachyphyllum obesum Heer, Brachyphyllum ponsi sp. nov., Brachyphyllum araripense sp. nov., Tomaxellia aff. T. biforme Archangelsky, Toxamellia aff. T. degiustoi e Pseudofrenelopsis sp. As Gnetales ocorrem na forma das espécies Limaephyton cratense gen. et sp. nov., Limaephyton duartei gen. et sp. nov. e Limaephytophyllum mohrium gen. et sp. nov. Características morfológicas, epidérmicas e anatômicas presentes nos macrofitofósseis da Formação Crato, evidenciam adaptações a um ambiente de baixa umidade. Esta flora se desenvolveu dentro da Região Equatorial, numa área intracontinental sob condições climáticas áridas e semi-áridas. / Crato Formation, located in the Araripe Basin, Northeastern Brazil, bears one of the most important Lower Cretaceous fóssil plant Record. The fossils have an excellent preservation, usually low fragmentated, with attached organs and epidermic and anatomic features delicatedly replaced by iron oxides. As it happens worldwide, gymnosperms were the dominant group in the Lower Cretaceous Crato Formation paleoflora, existing as Bennettitales, Coniferales e Gnetales. Bennettitales were an apparently scarce component, represented by the species Otozamites sp. and Zamites sp. Between the Coniferales, are the families Araucariaceae and Cheirolepidiaceae, the Araucariaceae recorded by the species Araucarites vulcanoi Duarte and Araucarites kunzmanni sp. nov.; Cheirolepidiaceae, the most diverse group, is registered by species Brachyphyllum obesum Heer, Brachyphyllum ponsi sp. nov., Brachyphyllum araripense sp. nov., Tomaxellia aff. T. biforme Archangelsky, Toxamellia aff. T. degiustoi e Pseudofrenelopsis sp. As Gnetales are documented by the species Limaephyton duartei gen. et sp. nov. and Limaephytophyllum mohrium gen. et sp. nov. Morphologic, epidermic and anatomic features founded in the plant fossils from Crato Formation, evidence low moisture environment adaptations. That flora was developed in the Equatorial Region, in an intracontinental area with arid to semi-arid climatic conditions.
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Taphonomie de l'assemblage de macrorestes fossiles de vertébrés du Lagerstätte d'Angeac-Charente (Crétacé inférieur, Charente, France) / Taphonomy of the assemblage of vertebrate fossil macroremains of the Lagerstätte of Angeac-Charente (Lower Cretaceous, Charente, France)Rozada, Lee 04 June 2019 (has links)
Les opportunités de reconstituer l’écologie et les comportements d’individus et d’espèces de vertébrés éteints sont rares. Plusieurs grands assemblages de vertébrés fossiles datant de la fin du Jurassique au début du Crétacé fournissent des informations sur la biodiversité et les communautés de vertébrés terrestres. Cependant, à l’exception du Lagerstätte de Las Hoyas (Crétacé inférieur, Espagne), les fossiles de ces assemblages ont été retrouvés sur un large éventail géographique, stratigraphique et/ou temporel. Cette thèse présente les résultats d’une étude taphonomique, couplée avec des données néotaphonomiques, paléontologiques, ichnologiques, sédimentologiques et géochimiques, de l’assemblage de macrorestes fossiles de vertébrés du site du Crétacé inférieur d’Angeac-Charente, situé dans l’Ouest de la France. Neuf campagnes de fouilles menées depuis 2010 ont permis de récolter plusieurs milliers de macrorestes de vertébrés appartenant à 16 taxons différents, auxquels viennent s’ajouter d’abondants microrestes appartenant à 27 taxons de vertébrés supplémentaires, plusieurs centaines de coprolithes de termites et de vertébrés riches en inclusions végétales et osseuses, des centaines de remplissages naturels d’empreintes de dinosaures, de nombreux restes de végétaux, des moules de mollusques bivalves et gastropodes, ainsi que des ostracodes. L’ensemble sédimentaire est dominé par des argiles de décantation interrompues par des dépôts localisés de plus haute énergie (cours d’eau, inondation) déposé dans un environnement de zone humide de type marécage. De nombreuses figures de déformations synsédimentaires formées en milieu liquide sont conservées sous forme de « scènes figées ». Des empreintes attribuées à l’ichnogenre Deltapodus et conservées sous forme de remplissages de dépôt direct ont été produites par un groupe multigénérationnel de stégosaures. De nombreuses empreintes de sauropodes sont conservées en 3-D ou en 4-D sous forme de remplissages de profondeurs variables. L’assemblage osseux est multitaxique, très diversifié et comprend des taxons terrestres, amphibies et aquatiques d’eau douce. Il contient une combinaison de macrofossiles et microfossiles et s’est formé de manière complexe, avec l’intervention de multiples processus d’origine biologique, écologique et physique. Il est dominé par les dinosaures, en particulier une nouvelle espèce d’ornithomimosaure non-ornithomimidé, dont de nombreux restent résultent d’une mort en masse d’un troupeau multigénérationnel dominé par des juvéniles et subadultes. D’abondants restes de sauropodes ont été transportés sur une plus ou moins grande distance avant d’être déposés sur le site. De nombreuses traces de morsure à la surface des restes de carapaces appartenant à plusieurs individus de tortues Pleurosternon bullockii résultent du comportement de prédation du crocodylomorphe Goniopholis, avec l’utilisation de la technique « casse-noix ». Les modifications osseuses post-dépositionnelles, comme la désarticulation, les déplacements, réorientations, fractures et traces de surface, résultent principalement de l’intense piétinement par les dinosaures. Le Lagerstätte d’Angeac-Charente ouvre une fenêtre d’une résolution spatiale et temporelle exceptionnellement fine sur un écosystème terrestre ouest-européen du tout début du Crétacé dont les organismes étaient en interaction directe entre eux et avec leur environnement. / Opportunities to reconstruct the ecology and behaviour of individuals of extinct vertebrate species are rare. Several large assemblages of fossil vertebrate dating from the late Jurassic to the early Cretaceous provide information on biodiversity and terrestrial vertebrate communities. However, with the exception of the Lagerstätte of Las Hoyas (Lower Cretaceous, Spain), the fossils of these assemblages have been found over a wide geographical, stratigraphic and/or temporal range. This PhD thesis presents the results of a taphonomic study, coupled with neotaphonic, paleontological, ichnological, sedimentological and geochemical data, of the assemblage of vertebrate fossils macro-remains from the Lower Cretaceous site of Angeac-Charente, located in the western France. Nine excavation campaigns carried out since 2010 allowed to collect thousands of vertebrate macroremains belonging to 16 different taxa, to which are added abundant microremains belonging to 27 additional vertebrate taxa, hundreds of termite and vertebrate coprolites rich in plant and bone inclusions, hundreds of natural casts of dinosaur tracks, numerous plant remains, bivalve and gastropod casts, as well as ostracods. The sedimentary assemblage is dominated by settling clays interrupted by localized deposits of higher energy deposited in a swampy wetland environment. Many synsedimentary deformations formed in liquefied sediments are preserved as "frozen scenes". Tracks attributed to the ichnogenre Deltapodus and preserved as direct deposit infills were produced by a multigenerational group of stegosaurs. Many sauropod footprints of various depths are stored in 3-D or 4-D. The bone assemblage is multitaxic, highly diversified and includes terrestrial as well as freshwater amphibian and aquatic taxa. It contains a combination of macrofossils and microfossils and has been formed in a complex way, with the intervention of multiple processes of biological, ecological and physical origin. It is dominated by dinosaurs, especially a new species of non-ornithomimid ornithomimosaur, many of whom remain resulting from a catastrophic mass death of a multigenerational herd dominated by juveniles and subadults. Abundant sauropod remains were transported by water currents over various distance before their deposit on the site. Many bite marks on the surface of shell remains belonging to several Pleurosternon bullockii turtle individuals result from the predatory behaviour of the crocodylomorph Goniopholis, with the use of the "nutcracker" technique. Post-depositional bone modifications, such as disarticulation, displacements, reorientations, fractures, fissures and surface marks, result mainly from intense trampling by dinosaurs. The Angeac-Charente Lagerstätte opens a window of exceptionally fine spatial and temporal resolution on a western European terrestrial ecosystem from the very beginning of the Cretaceous whose organisms interacted directly with each other and with their environment.
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Mudgases geochemistry and factors controlling their variabilityVlad, Daniela 06 1900 (has links)
Carbon isotope analyses of gases extracted from drilling muds while drilling in the Western Canada Sedimentary Basin (WCSB) can be used to create carbon isotopic depth profiles. These profiles provide essentially continuous data through the stratigraphic section, offering a unique opportunity to study the in-situ gases in various rock matrices. Carbon isotope and molecular compositions of Jurassic - Cretaceous mud gases have been examined from ten depth profiles in the undisturbed WCSB.
The isotopic profiles are surprisingly complex, showing numerous inflections and deviations towards increasing and decreasing carbon isotope values (13C) and wetness index with depth that suggest a correlation with the stratigraphic framework and can be explained in terms of the origin and alteration of the gases. However, the gas isotope geochemistry must be incorporated and applied in a multidisciplinary approach in order to gain a better understanding of causes of variations.
The discernible degree of correlativity of carbon isotope trends between the WCSB wells are likely to be related to the presence of major gas compartments bounded by stratigraphic surfaces, compartmentalization of the gas being strongly influenced by stratigraphic variations. The majority of these boundaries act as effective barriers to gas migration. Mudgas geochemistry is best employed in conjunction with petrophysical analysis and conversion into mineralogy, for defining details of transition zones and reservoir compartments.
Combined evidence suggests that isotopic variability of WCSB gases is only partly induced by source maturity at one single location. The main shifts of carbon isotope ratios are likely to be related to the physical properties of the rocks, differences between organic precursors (type II versus type III kerogen), total organic carbon (TOC) content, gas biodegradation and mixing.
The present thesis demonstrates that the carbon isotopic mud gas profiles represent a powerful tool that provide information about the compartmentalization of the gas, the effectiveness of low permeability barriers, the origin, alteration and maturity of gases, and the regional gas dynamics. Mudgas geochemistry proves to be one part of the puzzle in the investigation of regional gas dynamics, and should be integrated with geological information, lithostratigraphic-, and sequence stratigraphic information, petrographic information and geophysical data.
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Identification of pore type and origin in a Lower Cretaceous carbonate reservoir using NMR T2 relaxation timesLodola, Domenico Domenico 30 September 2004 (has links)
Determining the distribution of porosity and permeability is one of the main challenges in carbonate petroleum reservoir characterization and requires a thorough understanding of pore type and origin, as well as their spatial distributions. Conventional studies of carbonate reservoirs require interpretation and analysis of cores to understand porosity. This study investigates the use of NMR logs in the determination of pore type and origin. This study is based on the analysis of both thin section petrographic and NMR data from a single well that cored the Lower Cretaceous (Aptian) shelf carbonates belonging to the Shuaiba Formation of the Middle East. Photographs of thin sections were used to determine pore type and origin according to Ahr's genetic classification of carbonate porosity. Descriptive statistics and modeling were used to analyze the NMR T2relaxation time distributions. Descriptive statistical analyses included estimating arithmetic average, standard deviation, skewness, median, mode and 90th percentile. T2modeling was performed by fitting multiple log-normal distributions to the measured T2distribution. Data from thin section petrography and from NMR measurements were then compared using conditional probabilities. As expected, thin section analysis revealed the predominance of mud-supported fabrics and micropores between matrix grains Vugs and dissolved rudistid fragments account for most of the macro porosity. Descriptive statistics showed that the mode and th percentile of the T2distribution had the greatest power to discriminate pores by origin. The first principal component (PC1) of the mode-90th percentile system was then used to compute the probabilities of having each pore origin, knowing that PC1 belongs to a given interval. Results were good, with each origin being predictable within a certain range of PC1. Decomposition of the T2distributions was performed using up to 3 log-normal component distributions. Samples of different pore origin behaved distinctively. Depositional porosity showed no increase in fit quality with increasing number of distributions whereas facies selective and diagenetic porosity did, with diagenetic porosity showing the greatest increase.
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