Subsidence is one of the main factors controlling the stratigraphy and overall stratal architecture in tectonically active basins. This was particularly important in the Western US Cordilleran foreland and Laramide basins when some other controls were minor, e.g. reduced eustatic fluctuations in the late Cretaceous greenhouse period. The first part of the dissertation examines the upper Campanian Williams Fork Clastic Wedge (WFCW) in southern Wyoming and northern Colorado, through an outcrop and subsurface database. The WFCW built out from the Sevier orogenic belt like earlier clastic wedges, but its large-scale geometry changed as basement involved Laramide structures partitioned it. At the center of the WFCW there is an extensive fluvial sandstone sheet, the Canyon Creek Member of the Ericson Formation. From its proximal to distal reaches (~200 km) there is a first order trend of stratigraphic thickening and net-to-gross reduction, and a change from braided to meandering depositional style. These trends are caused by isostatic rebound of the foreland basin during periods of relative quiescence in the Sevier orogenic belt and by the eastward migration of dynamic subsidence. However, this long spatial trend was markedly modified by differential subsidence across Laramide-style structures. The Campanian age initiation of the Laramide structures appears to be earlier than the Maastrichtian to Paleogene age commonly attributed to the initiation of this orogeny. The second part of this research focuses on the transgressive limb of the WFCW, particularly on two sandstone bodies isolated in marine mudstones in the uppermost Almond Formation. The sandstone bodies previously interpreted as lowstand shoreline deposits are re-interpreted as transgressive shelf ridges generated by tidal currents and storm waves. There are limited examples of ancient tidal shelf ridges published and no facies model was described. Using Almond Fm. outcrops and examples from the literature, the diagnostic characteristics of storm and tidal shelf ridges are presented. The third part of the dissertation investigates the effects of differential subsidence on the large scale stratigraphic infill of a foreland basin through a geometric model and a series of flume experiments. The mathematical model and flume experiments show that despite constant allogenic forcing, three distinct autogenic responses in stratal architecture, associated with the imposed tectonic and sediment supply conditions are possible. The first response was “autoretreat”, where shoreline migration switched from initial progradation to retrogradation. The second response was progradation followed by constant aggradation. The third response was maintained progradation with a markedly accelerating rate, a new autogenic behavior termed “shoreline autoacceleration”. / text

Ce mémoire est consacré au Carbonifère et Permien du pays briançonnais entre Monétier et Névache. Sont abordés : - la stratigraphie des formations - les niveaux charbonneux : anthracite - la tectonique - les lambeaux houillers de réotier, St crépin - le Massif de Peyre Haute et du Prorel - la rive gauche de la Guisane et rive gauche et droite de la Clarée, le massif du chardonnet , de Rochachille et la vallée etroite

non renseigné

Description stratigraphique et tectonique

This dissertation presents results from a multi-year interdisciplinary study of the Late Quaternary geomorphic history of northwest Calvert Island, British Columbia, Canada. There is a considerable knowledge gap in the region pertaining to Cordilleran ice cover and extent as well as landscape response to a uniquely stable relative sea-level history. The objective of this study was to reconstruct this regional landscape response to deglaciation including post-LGM ice cover and extent, relative sea-level changes, coastal landform development, and climate and ecological variance. Methods used to inform this reconstruction included airborne lidar, aerial photography interpretation, sedimentary stratigraphy and detailed sedimentology of samples from shovel pits and lake cores, surficial geology and geomorphic mapping, palaeoecological examinations, and the development of a geochronology using radiocarbon and optical dating. To assist with landscape reconstruction, a new method was developed and used to differentiate littoral and aeolian sands in sediment samples that range in age from Mid to Late Holocene by using modern reference samples. The method utilized a standard optical microscope paired with freely available software (ImageJ) to characterize grain shape parameters. The method was tested on nearly 6,000 sand grains from samples of known and hypothesized depositional settings and was able to correctly identify the depositional setting for 76% of the samples. After testing, the method was used to differentiate littoral and aeolian sands in a number of shovel pit, exposure, and core sediment samples to give context to stratigraphic and geomorphic interpretations. A short-lived Late Pleistocene re-advance of Cordilleran ice occurred in the study area, with radiocarbon ages indicating ice advanced to, and then retreated from, the western edge of Calvert Island between 14.2 and 13.8 ka cal BP, respectively. Sedimentological and palaeoecological information that suggests a cold climate and advancing/retreating glacier as well as lidar remote sensing and field-based geomorphic mapping of moraines in the region provide evidence of the re-advance. After ice retreated from the area, a broad suite of geomorphic landforms developed, including flood plains, iv aeolian dunes, beaches, spits, marshes, and tombolos. Coastal reworking was extensive, with progradation rates greater than 1 m a-1 occurring in some locations during the Late Holocene. These data provide the first evidence of a re-advance of the retreating ice sheet margin on the central coast of British Columbia, contribute an important methodology to advance Quaternary reconstructions, and give a unique account of the geomorphic development of a Pacific Northwest coastline that experienced little relative sea-level change over the Late Pleistocene and Holocene. Results help fill a spatial and temporal gap in the landscape history of British Columbia and have implications for climate and sea-level reconstructions, early human migration patterns, and the palaeoenvironment of an understudied area of the Pacific Northwest coast of North America. / Graduate / 0368 / 0372 / 0426 / jeamer7@gmail.com

Many recent studies have sought to understand the response of barrier islands and their attendant marshes to sea level rise. The Mississippi River delta plain, specifically the Chandeleur Islands and associated interior wetlands in eastern Louisiana, serves as an excellent natural laboratory for studying these responses. This region is presently undergoing the highest rates of shoreline erosion (> 15 m yr -1) in North America as wetlands are converted to open water in a regime of subsidence-driven rapid relative sea-level rise (~1 cm yr-1). Three conceptual models were developed based on the geomorphic relationships observed in the marsh that describe and predict shoreline processes as the Chandeleur Islands continue to disintegrate and submerge. These models indicate that shells are the dominant shoreline-forming material in the marsh due to the lack of sand-rich strata in the subsurface of the marsh.

During the last half century researchers have suggested that active deformation driven by neotectonic activity has locally influenced areas of southeastern Louisiana in the form of wetland loss and coastal erosion. This study, within the Pearl River Delta Area of Louisiana, applied geomorphologic and stratigraphic methods of analysis to assess whether evidence of recent fault motion is present within the shallow, unconsolidated Holocene strata of the study area. Geomorphological historical change analyses focused on meander patterns, elongated water bodies and spatial changes in vegetation identify areas where fault motion may have recently occurred. The shallow stratigraphy was then investigated in these locations using vibracores and seismic reflection profiling. Facies relationships coupled with radiocarbon ages of select stratigraphic intervals led to the development of a detailed stratigraphic framework. Based on these relationships, data suggest that subsurface deformation, resultant of neotectonic activity, has recently occurred within the shallow, unconsolidated Holocene strata.

The western portion of the Mississippi/Atwater fold belt in the Gulf of Mexico contains what is known as The Green Knoll Salt Dome. The creation and growth of this salt diapir is punctuated by salt deposition, salt migration, sediment loading, and is linked to the “Frampton” fold belt. An indicator of these growth periods is exhibited in an angular unconformity (halo-kinetic sequence boundary) that flanks the diapir. This unconformity developed during the Miocene-Pliocene chronostratigraphic boundary. The “Redwood” (Green Canyon 1001) prospect was drilled after the discovery of middle Miocene sands containing hydrocarbons in the Mad Dog field (GC 826). The objective Miocene sand in the “Redwood” borehole was thin due to this angular unconformity causing the sand to pinch out. An evaluation of seismic and well log data provided by Bureau of Ocean Energy Management indicated that the unconformity might not provide the seal needed to trap hydrocarbons on the flank of the salt dome, or it did not allow enough sand to be deposited. A palinspastic structural restoration of the Green Knoll Salt Dome revealed that the growth of the Green Knoll and Frampton are connected. It is still possible that if a well were to be drilled further down dip from where The “Redwood” prospect was drilled, one may find a potential hydrocarbon reservoir.

As campanhas de investigação geotécnica e geoambiental do subsolo utilizam diversos tipos de sondagem e ensaios com objetivo de mapear a distribuição espacial das unidades e definir os parâmetros de projeto específicos para cada tipo de intervenção. A etapa de identificação da distribuição e da constituição dos materiais é comum a grande parte dos projetos e normalmente é conduzida através de sondagens em campo que produzem uma perfilagem pontual e vertical do terreno. Os estudos realizados durante esta pesquisa tiveram como principal objetivo avaliar a influência da história geológica na execução e na interpretação dos ensaios de piezocone para identificação estratigráfica. Os ensaios de piezocone sísmico foram realizados com objetivo de identificar a interface entre solos lateríticos e os não-laterítico. Os ensaios de piezocone de resistividade foram realizados principalmente para avaliação de intrusões de cunhas de águas salinas em aqüíferos sedimentares rasos. Desta forma, foram selecionadas nove áreas localizadas em regiões com diferentes condições geológicas, representativas do território brasileiro. Abrangem sedimentos quaternários das planícies litorâneas, sedimentos cenozóicos de bacias tafrogênicas e solos tropicais desenvolvidos a partir de rochas sedimentares e ígneas da Bacia do Paraná. Os locais foram selecionados em função da disponibilidade de informações adequadas às análises pretendidas. Nos sedimentos os resultados dos ensaios de piezocone foram eficazes na caracterização estratigráfica, classificação dos sedimentos e estimativa de parâmetros de projeto a partir de correlações. Nestes sedimentos, a experiência internacional, adquirida principalmente em sedimentos da América do Norte e Europa, pôde ser utilizada. Os ensaios com piezocone de resistividade foram eficazes em identificar intrusões salinas no aqüífero, contribuindo também para identificação da estratigrafia do perfil. Nestes sedimentos foram observadas relações consistentes entre a história de formação do perfil e as propriedades geotécnicas estimadas a partir da interpretação dos ensaios de piezocone. Já, nos solos tropicais, os processos de intemperísmo produzem transformações no perfil que dificultam a definição da estratigrafia, a classificação dos solos e a estimativa de parâmetros com base em correlações. Em solos tropicais, os ensaios com piezocone de resistividade foram ineficientes na identificação da profundidade do nível d’água e na definição da sequência estratigráfica, provavelmente devido à presença de óxidos de ferro e nível de água profundo. Já, os ensaios de piezocone sísmico foram eficazes para diferenciar os solos de comportamento laterítico dos de comportamento não-laterítico através da relação Go/qc. Conclui-se que o entendimento da história geológica é fundamental na interpretação dos ensaios de piezocone, principalmente na etapa de integração entre ensaios pontuais, para identificação da geometria e variabilidade dos solos. A quantidade de processos ou de variáveis independentes que contribuem para a formação do perfil de solo normalmente aumenta a variabilidade. Neste sentido, ensaios combinados, como o piezocone sísmico, onde vários parâmetros podem ser obtidos em um mesmo ponto, contribuem para minimizar os efeitos da variabilidade na estimativa de parâmetros de projeto / In situ tests for geotechnical and geo-environmental site investigation embraces a variety of soundings and tests to map and define stratigraphic logging and specific design parameters for each kind of job. Stratigraphic logging and soil classification are a common stage to all investigation programs and frequently they are performed throughout logging tests which results in local vertical information. The main objective of this research is to evaluate the influence of geological history in the interpretation of piezocone tests for stratigraphic logging. Seismic piezocone tests were carried out to try to identify difference response between lateritic and non lateritic soils. Resistivity piezocone tests were carried out to evaluate salt-water intrusion within a shallow sedimentary aquifer. In this sense, nine sites with different geologic conditions, representing extensive area from Brazil, were selected and investigated. They include quaternary sediment sequences on the brazilian coast, tafrogenic sedimentary sequences and tropical soils originated from weathering of Paraná basin sedimentary and igneous rocks. Piezocone tests were effective for stratigraphic logging, sediment classification as well as to estimate geotechnical design parameters based on correlations for sedimentary sediments. For these type of soils, the international experience developed for sedimentary soils from North America and Europe can be used. Resistivity piezocone tests were effectively useful to identify salt-water intrusion within a sedimentary aquifer and contributed to refine soil stratigraphy. Consistent relations between geologic history and geotechnical properties were established based on piezocone test results. In the other hand, the weathering process produces profile transformations in the tropical soils and imposes limitations to stratigraphy definition, soil classification and to estimate geotechnical soil parameters based on these correlations. For tropical soils, the resistivity piezocone test was not efficient to identify the groundwater level and to refine stratigraphic logging, probably due to the presence of iron oxides and deep groundwater. The seismic piezocone tests were effective to separate lateritic and non-lateritic soils throughout the relation between maximum shear modulus and poit resistance (Go/qc). It is concluded that the geological information is fundamental for the interpretation of piezocone results, especially to integrate several logging test data, to identify spatial distribution and variability of soil layers. In this sense, combined tests, such as the seismic piezocone, where more than one parameter can be measured at the same location, contribute to minimize variability effects in the estimation of geotechnical soil parameters

O monumento histórico normalmente constitui-se por acúmulos de estratos, mudanças advindas de novas construções ou demolições que se sucedem no tempo e deixam marcas e testemunhos materiais. E é como tal que, do ponto de vista da ciência, cultura e ética, deverá ser compreendido. Isso faz com que seja imprescindível o domínio da estratigrafia pelos agentes que lidam com o patrimônio cultural. A estratigrafia ou análise estratigráfica abrange o estudo da estratificação, ou seja, o estudo das ações construtivas e destrutivas em um edifício. Contudo, no Brasil, a sua utilização ainda é incipiente, pouco difundida. A grande maioria dos profissionais utiliza apenas a microestratigrafia para as pinturas murais e não usa o método consolidado para edifícios com e sem revestimento. Por isso, o objetivo geral deste trabalho consiste numa apresentação e também numa reflexão sobre essa ferramenta de origem arqueológica como um dos instrumentos primordiais para projeto e obra de Restauro. A compreensão e reflexão com relação ao tema são alcançadas a partir de pesquisa bibliográfica na qual se analisam as experiências em andamento nos principais centros de estudo localizados na Itália e Espanha. A dissertação está dividida em quatro capítulos: o primeiro esclarece conceitos ligados à análise estratigráfica; o segundo e terceiro capítulos abordam a metodologia de aplicação desta ferramenta (sendo o segundo para edifícios sem revestimento e os métodos de datação e o terceiro para os edifícios com revestimento); o quarto capítulo tem o importante papel de abordar questões conceituais, técnicas e metodológicas do projeto de restauro a partir de casos concretos e, dessa forma, demonstrar que não basta apenas conhecer, mas saber o que fazer com este conhecimento. Assim, esta dissertação de mestrado pretende contribuir para a divulgação do método da estratigrafia no Brasil ao agrupar experiências internacionais significativas para a reflexão e a inovação das tradicionais condutas de conhecimento do edifício. Deve-se deixar claro que tal contribuição seria muito útil para formação de equipes especializadas e para instigar futuras pesquisas. / The historical monument is constituted by the juxtaposition of layers, changes that came from new constructions or demolitions, which succeed over time. They constitute material testimonials and impressions which must be comprehended through the perspectives of scientific, cultural and ethical studies. For so, the knowledge of Stratigraphy by cultural heritage specialists is indispensable. Stratigraphy - or Stratigraphic Analysis -consists of the study of constructive or destructive actions in a building. However, in Brazil, its use remains incipient and not widely disseminated. The majority of professionals applies microstratigraphy mostly to wall paintings, rarely using the broader and consolidated technique to coated or uncoated buildings. Therefore, it is the general objective of this work not to only make a presentation of Stratigraphy, but also to reflect upon this archaeological-based tool as a prime instrument for a restoration project and a field work. The understanding and reflection are based on bibliographical research, in which ongoing experiences from the main Italian and Spanish study centers are analyzed. This piece is divided in four chapters: the first clarifies stratigraphic analysis concepts; the second and third chapters approach the methodology and its application as a tool (the second chapter comprises uncoated buildings and dating methods; whereas the third one is about coated buildings); the fourth chapter brings forth the importance of discussing restoration project concepts, techniques and methods, by using concrete cases in order to perceive the need of not only knowing the theoretical concepts, but also understanding how to apply them. This thesis intends to help disclosing the stratigraphic method in Brazil by gathering significant international experiences with the aim of stimulating reflection and innovation regarding traditional aspects in building interventions. It is important to stress that such contribution would be very useful in professional formation and in stimulating future researches.