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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Compartimentação do meio físico, evolução morfológica e aspectos morfotectônicos em São Thomé das Letras (MG)

Marques Neto, Roberto [UNESP] 29 October 2007 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-10-29Bitstream added on 2014-06-13T19:15:23Z : No. of bitstreams: 1 marquesneto_r_me_rcla.pdf: 2544757 bytes, checksum: c23c3787ee6420768ab406cae71bd6c2 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O propósito da presente dissertação consiste na determinação de unidades de paisagem para o município de São Thomé das Letras (MG), no estudo da evolução morfológica da área e na apreciação de aspectos morfotectônicos. O cumprimento dos objetivos estipulados demandou uma série de dispositivos analíticos que se coadunaram para a interpretação da fisiologia da paisagem e para o discernimento de diferentes unidades paisagísticas representadas em documento cartográfico de síntese. O estudo da evolução morfológica demandou a avaliação de elementos do quadro genético-evolutivo regional como meio para o entendimento dos processos operantes em âmbito local. A pesquisa focalizou a ocorrência e posicionamento de diferentes superfícies de erosão na área de estudo, diferenciando remanescentes relacionados à Superfície Sul-Americana, do Terciário Inferior, de modelados de dissecação mais recentes, de idade plio-pleistocência. A esta etapa se somou, com ênfase, estudos interessados na evolução morfológica levada a efeito durante o Quaternário em consonância com as oscilações climáticas que marca o referido período, o que se deu por meio do estudo de processos de pedimentação recente e dos depósitos correlatos, da avaliação da cobertura vegetal atual e dos fenômenos cársticos operantes, também sendo estimada a evolução do relevo com enfoque na estrutura, que confere tipicidade apalachiana para a morfologia local e regional. No tocante aos aspectos morfotectônicos, a pesquisa se valeu da análise do relevo e da drenagem, enfando os fenômenos neotectônicos com base na identificação de feições morfológicas indicativas (shutter ridges, capturas, migração lateral de cursos dágua, canais fluviais com trechos excessivamente retilíneos, etc.) e na identificação e interpretação dos principais lineamentos. Os estudos morfotectônicos... / The aim of this present dissertation consists in the determination of landscape unity for the town of São Thomé das Letras (MG), in the study of the area morphological evolution and appreciation of morphotectonic aspects. The fulfilment of stipulated purpose demanded a serie of analytical device that were gathered for the comprehention of landscape phisiology as well as the understanding of different landscape unities represented in graphic-chart document of synthesis. The study of morphological evolution demanded the evaluation of components the regional genetic-evolutive chart as so as to understand the operating process in local range. The research focused the occurence and status of different erosion surface in the studied area, differenciating remainders related to Superfície Sul-Americana of low Terciary, of latest dissection molded, of plio-pleistocene age. To such stage, with emphasis, was added studies interested in the morphological evolution effectuatedduring the Quaternary in consonance with climatic fluctuations that mark the referred era, which happened by means of process study of recent pedimentation and correlated deposits from evaluation of current vegetal covering and operating carstic phenomenon, also evolution of relief beig estimated focusing the structure, that grants appalachian tipicality to regional and local morphology. Regarding the morphotectonic aspects, the research turned to the relief analisis and drainage emphasizing the neotectonic phenomena based on identification of indicative morphological features (shutter ridges, captures, water-course lateral migration, river channel with excessively right-lined streches, etc.) and identification and interpretation of main lineages. The morphotectonic studies were subsidized by measuring the geomorphic rate useful for estimating neotectonic effects, notoriously the asymmetry Factor of Drainage Basins... (Complete abstract click electronic access below)
2

Compartimentação do meio físico, evolução morfológica e aspectos morfotectônicos em São Thomé das Letras (MG) /

Marques Neto, Roberto. January 2007 (has links)
Orientador: Adler Guilherme Viadana / Banca: Archimedes Perez Filho / Banca: Francisco Sérgio Bernardes Ladeira / Resumo: O propósito da presente dissertação consiste na determinação de unidades de paisagem para o município de São Thomé das Letras (MG), no estudo da evolução morfológica da área e na apreciação de aspectos morfotectônicos. O cumprimento dos objetivos estipulados demandou uma série de dispositivos analíticos que se coadunaram para a interpretação da fisiologia da paisagem e para o discernimento de diferentes unidades paisagísticas representadas em documento cartográfico de síntese. O estudo da evolução morfológica demandou a avaliação de elementos do quadro genético-evolutivo regional como meio para o entendimento dos processos operantes em âmbito local. A pesquisa focalizou a ocorrência e posicionamento de diferentes superfícies de erosão na área de estudo, diferenciando remanescentes relacionados à Superfície Sul-Americana, do Terciário Inferior, de modelados de dissecação mais recentes, de idade plio-pleistocência. A esta etapa se somou, com ênfase, estudos interessados na evolução morfológica levada a efeito durante o Quaternário em consonância com as oscilações climáticas que marca o referido período, o que se deu por meio do estudo de processos de pedimentação recente e dos depósitos correlatos, da avaliação da cobertura vegetal atual e dos fenômenos cársticos operantes, também sendo estimada a evolução do relevo com enfoque na estrutura, que confere tipicidade apalachiana para a morfologia local e regional. No tocante aos aspectos morfotectônicos, a pesquisa se valeu da análise do relevo e da drenagem, enfando os fenômenos neotectônicos com base na identificação de feições morfológicas indicativas (shutter ridges, capturas, migração lateral de cursos dágua, canais fluviais com trechos excessivamente retilíneos, etc.) e na identificação e interpretação dos principais lineamentos. Os estudos morfotectônicos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this present dissertation consists in the determination of landscape unity for the town of São Thomé das Letras (MG), in the study of the area morphological evolution and appreciation of morphotectonic aspects. The fulfilment of stipulated purpose demanded a serie of analytical device that were gathered for the comprehention of landscape phisiology as well as the understanding of different landscape unities represented in graphic-chart document of synthesis. The study of morphological evolution demanded the evaluation of components the regional genetic-evolutive chart as so as to understand the operating process in local range. The research focused the occurence and status of different erosion surface in the studied area, differenciating remainders related to Superfície Sul-Americana of low Terciary, of latest dissection molded, of plio-pleistocene age. To such stage, with emphasis, was added studies interested in the morphological evolution effectuatedduring the Quaternary in consonance with climatic fluctuations that mark the referred era, which happened by means of process study of recent pedimentation and correlated deposits from evaluation of current vegetal covering and operating carstic phenomenon, also evolution of relief beig estimated focusing the structure, that grants appalachian tipicality to regional and local morphology. Regarding the morphotectonic aspects, the research turned to the relief analisis and drainage emphasizing the neotectonic phenomena based on identification of indicative morphological features (shutter ridges, captures, water-course lateral migration, river channel with excessively right-lined streches, etc.) and identification and interpretation of main lineages. The morphotectonic studies were subsidized by measuring the geomorphic rate useful for estimating neotectonic effects, notoriously the asymmetry Factor of Drainage Basins... (Complete abstract click electronic access below) / Mestre
3

Foraminifera and tidal notches: dating neotectonic events at Korphos, Greece

Nixon, Chantel 10 1900 (has links)
<p> Foraminiferal and thecamoebian biofacies were documented in the modem Korphos marsh located on the western coast of the Saronikos Gulf, Greece in order to define the general ecological features (such as salinity and proximity to marine influence) of the environments they occupied. These constraints were later used to identify fossil biofacies in subsurface marsh sediments at Korphos. </p> <p> Positive marine tendencies identified in fossil biofacies distributions were used for the first time to radiocarbon date relative changes in sea-level implied by a series of discrete, submerged tidal notches and beach rock adjacent to the marsh along the coast. Magnitude of subsidence events based on notch and beach rock data were measured to 2.9m, 0.5m, 1.3m, 0.39m, 0.47m, and 0.34m. The relatively unaltered v-shape of each notch profile suggested that sea-level rise was rapid and episodic. </p> <p> A comparison between the tidal notches and beach rock and an isostatically corrected model of sea-level for this area isolated the tectonic contribution to sea-level change and revealed that at least four of the six sea-level indicators plotted well-below predicted sea-level during subsidence. Therefore, the gradual sea-level rise of the late Holocene was interrupted by at least four sub-meter to meter-scale, step-wise increases in relative sea-level during coseismic subsidence of the Korphos marsh. The results of this study show how the combination of geomorphological and salt-marsh records have the potential to remove errors stemming from a lack of datable material for notches and autocompaction of marsh sediments when reconstructing local sea-level change. </p> / Thesis / Master of Science (MSc)
4

Fractures and Fracture Filling in the Guelph Formation, Steetley Quarry Flamborough, Ontario

Campbell, Ian T. 04 1900 (has links)
<p> The North Quarry (north of Ontario Highway 4) is located in Flamborough Ontario. In it, rocks of the Guelph formation are well exposed. The Guelph formation consists of dolomite and at the North Quarry has an average thickness of 30m. These rocks are cut by three predominant joint sets which have no indication of shear motion. The 030° set was formed as a result of compaction and loading; It appears to represent an upward joint propagation mirroring the Algonquin Arch trend. Joint sets 120° and 160° are a north western analogue to the conjugate pair described by Nickelson and Hough (1967) in the north eastern United States.</p> <p> Vein data and sampled minerals, using techniques such as cathodoluminescence, photoluminescence, and isotope analysis enable paragenesis of joint propagation and crystallization relationships to be inferred. Possible stress field configurations have been deduced from these data. The joint set 030° was the first to open. Next, a minor east-west trending set opened. Joint sets 120° and 160° are the last to open. The joints were infilled by cement in the order of Organics > Calcite > Sulphides > Iron Oxides. Buckle heaves in the quarry were unreliable indicators of neotectonic stress.</p> / Thesis / Bachelor of Science (BSc)
5

Investigation of Neotectonic Activity within the Shallow, Unconsolidated Stratigraphy of the Pearl River Delta Area, Louisiana

Fischer, Dane 05 August 2010 (has links)
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.
6

Estudo morfotectônico da região da serra de São Pedro e do baixo Piracicaba/SP / Morphotectonic Study of the São Pedro Ridge and Lower Piracicaba Region/SP

Pinheiro, Marcos Roberto 30 October 2014 (has links)
As cuestas são definidas como uma forma de relevo dissimétrico, composta por uma vertente em declive íngreme de um lado e uma rampa em declive suave no reverso, decorrente da erosão diferencial das rochas. A região da Serra de São Pedro/SP, área de ocorrência de basaltos juro-cretáceos (topo da escarpa) e arenitos eólicos (escarpa e glacis) do Triássico ao Cretáceo Médio, consiste em uma das zonas mais típicas das cuestas na Bacia do Paraná, porém a configuração geometrizada do relevo da área, do sistema fluvial e até do baixo rio Piracicaba sugerem um controle tectônico das formas. Nesse sentido, o objetivo deste trabalho foi verificar o possível controle tectônico no relevo da Serra de São Pedro e do Baixo Piracicaba, focalizando a ação da Neotectônica, tendo como hipótese a existência de um forte controle das estruturas modernas sobre as formas. Os resultados mostraram que a atividade neotectônica na área é caracterizada principalmente pela atividade de falhas transcorrentes e normais subverticais WNW-ESE, W-E, NW-SE e NE-SW, ambas de pequeno rejeito e de impacto reduzido na morfologia do relevo. A influência das estruturas nas formas é mais intensa no sistema fluvial, comandando a dissecação do relevo de toda a área a partir de linhas estruturais que correspondem aos planos de juntas, grandes fraturamentos e falhas, ainda que a tectônica recente seja responsável pelo controle da direção apenas dos canais de 1º e 2º ordens. A Neotectônica condiciona ainda a formação de facetas triangulares na frente da escarpa da Serra de São Pedro, provoca perturbações de depósitos fluviais quaternários, anomalias no perfil longitudinal dos rios e inflexões dos interflúvios e canais de drenagem, além de pequenos basculamentos de blocos que causam a formação e degradação de terraços fluviais nos afluentes da margem direita do baixo Piracicaba. Essas informações são coerentes com os dados das estruturas medidas e materiais descritos em campo, bem como com as informações do contorno estrutural e dados geofísicos da área. Apesar do claro registro de neotectônica na região da Serra de São Pedro e do Baixo Piracicaba, os resultados demonstraram que a magnitude dessa atividade é reduzida e o seu impacto no relevo é pequeno, sendo que a configuração geomorfológica atual é mais influenciada por fatores litológicos, pela disposição das camadas sedimentares das rochas, pelos (paleo)climas e pela orientação/distribuição de estruturas tectônicas anteriores ao Neógeno, refutando assim a hipótese inicial do trabalho. / Cuestas are asymmetric landforms characterized by a steep slope along the plateau front and a gentle slope on its reverse, and they are interpreted as a relief formed by differential erosion of rocks. The São Pedro Ridge (Serra de São Pedro)/SP region, area with occurrence of juro-cretacic basalts (top of the ridge) and Triassic medium Cretaceous aeolian sandstone (scarp and glacis), is one of the most typical examples of the cuestas in the Paraná Basin. Although São Pedro Ridge is considered a cuesta, the geomorphological settings and the fluvial system (including the Lower Piracicaba River) of the area suggest a tectonic control on the landforms. Thus, the aim of this research was to verify a possible tectonic control on the São Pedro Ridge and Lower Piracicaba River landforms, emphasizing the Neotectonic influence. The hypothesis is that modern tectonics has a strong influence in the actual landforms. The results showed that the neotectonic activity in the study area is characterized mainly by sub-vertical strike-slip and normal faults WNW-ESE, WE, NW-SE and NE-SW, both with very small offsets and inconspicuous impact in the relief. The influence of the tectonic activity in the landforms is more intense in the fluvial system, controlling the relief dissection from joint planes, large fractures and faults, though modern tectonics is responsible for the control of the direction only of first and second order drainage channels. Neotectonics also controls the formation of triangular facets at the escarpment front of the São Pedro Ridge, faulting in quaternary fluvial deposits, anomalies in the longitudinal profiles of streams and changes in the direction of ridge lines and watercourses (river bends), as well as small block tilting which influences the formation and degradation of fluvial terraces of the Piracicaba right margin tributaries. These interpretations are coherent with the data set concerning the structures measured and materials characterized in the field, as well as with the information about the structural contour and geophysical data of the area. Despite the clear record of neotectonics in the São Pedro Ridge and Lower Piracicaba River region, the results demonstrated that the magnitude of the modern tectonic activity is small, and that the actual geomorphological configuration is more influenced by lithological factors, paleoclimates and the arrangement of sedimentary rock layers and pre-Neogene tectonic structures, thus refuting the initial hypothesis of this study.
7

Neotectonics And Evolution Of The Eskipazar Basin, Karabuk

Biryol, Berk Cemal 01 July 2004 (has links) (PDF)
Study area, the Eskipazar Basin, is located in the western part of the North Anatolian Fault System. It is a 3-5 km wide, 10 km long and NWSE trending depression, bounded by a complex array of oblique-slip normal faults and strike-slip faults. The Eskipazar Basin is interpreted to be a superimposed basin. The basin fill is composed of two different units deposited under the control of different tectonic regimes, namely the paleotectonic and the neotectonic regimes. The latest paleotectonic fill of the basin is the fluvio-lacustrine deposits of the paleotectonic Eskipazar formation. This formation is unconformably overlain by a group of neotectonic units namely, the Budaklar, the Karkin and the imanlar formations. The unconformity in between these paleotectonic and neotectonic units represents the time interval during which the paleotectonic period comes to end and the neotectonic period started. Thus, onset age of the strike-slip neotectonic regime in the study area is Late Pliocene (&amp / #8764 / 2.6 My). Common basin margin-bounding faults of the Eskipazar Basin are the Kadilar fault set, the Beytarla Fault Zone, the Budaklar fault set, the Arslanlar fault set, the Dibek fault, the Karkin fault, the Boztepe fault and the Acisu fault. These faults display well preserved fault scarps, in places. Morphological expressions of these faults and their geometrical relationships to regional stress system indicate that these faults are mostlystrike-slip faults with normal component. However the Kadilar fault set displays a different characteristic, being the major fault controlling the basin to the west and it is indeed an oblique slip normal fault. Long term seismicity and their epicentral distribution in and very close to the study area suggest that the Eskipazar basin is located in an area of seismic quiescence, nevertheless the morphotectonic expressions of the faults exposing in the basin suggest that these faults are active. Since the most of settlements are located on different lithologies of poorly consolidated deposits of the Eskipazar formation susceptible to landslides, the area is open to future earthquake hazard. Therefore, structures and settlements have to be constructed on strong ground away from active faults.
8

Estudo morfotectônico da região da serra de São Pedro e do baixo Piracicaba/SP / Morphotectonic Study of the São Pedro Ridge and Lower Piracicaba Region/SP

Marcos Roberto Pinheiro 30 October 2014 (has links)
As cuestas são definidas como uma forma de relevo dissimétrico, composta por uma vertente em declive íngreme de um lado e uma rampa em declive suave no reverso, decorrente da erosão diferencial das rochas. A região da Serra de São Pedro/SP, área de ocorrência de basaltos juro-cretáceos (topo da escarpa) e arenitos eólicos (escarpa e glacis) do Triássico ao Cretáceo Médio, consiste em uma das zonas mais típicas das cuestas na Bacia do Paraná, porém a configuração geometrizada do relevo da área, do sistema fluvial e até do baixo rio Piracicaba sugerem um controle tectônico das formas. Nesse sentido, o objetivo deste trabalho foi verificar o possível controle tectônico no relevo da Serra de São Pedro e do Baixo Piracicaba, focalizando a ação da Neotectônica, tendo como hipótese a existência de um forte controle das estruturas modernas sobre as formas. Os resultados mostraram que a atividade neotectônica na área é caracterizada principalmente pela atividade de falhas transcorrentes e normais subverticais WNW-ESE, W-E, NW-SE e NE-SW, ambas de pequeno rejeito e de impacto reduzido na morfologia do relevo. A influência das estruturas nas formas é mais intensa no sistema fluvial, comandando a dissecação do relevo de toda a área a partir de linhas estruturais que correspondem aos planos de juntas, grandes fraturamentos e falhas, ainda que a tectônica recente seja responsável pelo controle da direção apenas dos canais de 1º e 2º ordens. A Neotectônica condiciona ainda a formação de facetas triangulares na frente da escarpa da Serra de São Pedro, provoca perturbações de depósitos fluviais quaternários, anomalias no perfil longitudinal dos rios e inflexões dos interflúvios e canais de drenagem, além de pequenos basculamentos de blocos que causam a formação e degradação de terraços fluviais nos afluentes da margem direita do baixo Piracicaba. Essas informações são coerentes com os dados das estruturas medidas e materiais descritos em campo, bem como com as informações do contorno estrutural e dados geofísicos da área. Apesar do claro registro de neotectônica na região da Serra de São Pedro e do Baixo Piracicaba, os resultados demonstraram que a magnitude dessa atividade é reduzida e o seu impacto no relevo é pequeno, sendo que a configuração geomorfológica atual é mais influenciada por fatores litológicos, pela disposição das camadas sedimentares das rochas, pelos (paleo)climas e pela orientação/distribuição de estruturas tectônicas anteriores ao Neógeno, refutando assim a hipótese inicial do trabalho. / Cuestas are asymmetric landforms characterized by a steep slope along the plateau front and a gentle slope on its reverse, and they are interpreted as a relief formed by differential erosion of rocks. The São Pedro Ridge (Serra de São Pedro)/SP region, area with occurrence of juro-cretacic basalts (top of the ridge) and Triassic medium Cretaceous aeolian sandstone (scarp and glacis), is one of the most typical examples of the cuestas in the Paraná Basin. Although São Pedro Ridge is considered a cuesta, the geomorphological settings and the fluvial system (including the Lower Piracicaba River) of the area suggest a tectonic control on the landforms. Thus, the aim of this research was to verify a possible tectonic control on the São Pedro Ridge and Lower Piracicaba River landforms, emphasizing the Neotectonic influence. The hypothesis is that modern tectonics has a strong influence in the actual landforms. The results showed that the neotectonic activity in the study area is characterized mainly by sub-vertical strike-slip and normal faults WNW-ESE, WE, NW-SE and NE-SW, both with very small offsets and inconspicuous impact in the relief. The influence of the tectonic activity in the landforms is more intense in the fluvial system, controlling the relief dissection from joint planes, large fractures and faults, though modern tectonics is responsible for the control of the direction only of first and second order drainage channels. Neotectonics also controls the formation of triangular facets at the escarpment front of the São Pedro Ridge, faulting in quaternary fluvial deposits, anomalies in the longitudinal profiles of streams and changes in the direction of ridge lines and watercourses (river bends), as well as small block tilting which influences the formation and degradation of fluvial terraces of the Piracicaba right margin tributaries. These interpretations are coherent with the data set concerning the structures measured and materials characterized in the field, as well as with the information about the structural contour and geophysical data of the area. Despite the clear record of neotectonics in the São Pedro Ridge and Lower Piracicaba River region, the results demonstrated that the magnitude of the modern tectonic activity is small, and that the actual geomorphological configuration is more influenced by lithological factors, paleoclimates and the arrangement of sedimentary rock layers and pre-Neogene tectonic structures, thus refuting the initial hypothesis of this study.
9

Caracterização geomorfológica e morfométrica da Folha Alhandra (1:25.000) / Geomorphical and Morphometrical Characterization of Alhandra Leaf (1:25.000)

Freitas, Gilvonete Maria Araujo de 23 March 2012 (has links)
Made available in DSpace on 2015-05-14T12:16:59Z (GMT). No. of bitstreams: 1 parte1.pdf: 5475254 bytes, checksum: 1a571217557e2d67cedb0f985af3b27d (MD5) Previous issue date: 2012-03-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With the aid of morphometric rates, the present work aimed at characterizing the geormorphology of the area corresponding to Alhandra Leaf 1:25.000, which is located mainly on Tabuleiros Litorâneos, formed largely by poorly consolidated sediments of Formação Barreiras. This geormorphology is associated with other elements of the physical environment with which the area studied keeps mutual interaction. In addition, this work searched for features that could indicate neotectonic action on the configuration of the relief and on the drainage pattern of the area. The forms of land occupation and use were also verified in comparison with the current legislation. Having this in mind, a bibliographical research was done in order to describe the theme and to characterize the geomorphological, geological, pedological and climatic aspects of the vegetation and the hidrography of the area. Considering the importance of geotechnology, we were able to describe more precisely the area by using the maps produced. With the level curves taken from Alhandra Leaf and the SPRING 5.1.7, hypsometric, clinographic and geomorphological maps were made. Also, by using the same software, satellite images, and field work, a map about the land occupation and use was produced. With the aid of the hypsometric and the clinographic maps, it was possible to measure the relief modeling and analyze the forms of land occupation and use, which were synthetised both in the land occupation and use map and also in the declivity irregular land occupation and use map, which was constructed by the overlapping of clinographic and land occupation and use maps. The geomorphological map made it possible to establish the chronological order (geological time), from the old soil formation to the most recent ones. Topographic profiles were constructed by the use of Microsoft Office Excel 2007 in order to observe details in the ground variation. As geomorphology is directly related to pedology, laboratory analyses were made (pH, soil density, particle density and granulometrics). Finally, Slope Length (SL) and drainage density (Dd) rates were created to investigate the drainage network with the aid of SPRING 5.1.7 software. The Slope Length (SL) rate was applied in order to verify the neotectonic influence, by correlating the results with the morphology of the relief. The drainage density (Dd) rate was used to identify points vulnerable to erosive processes and rates related to the production and to the transport of sediments, originated from interfluvial system. After applying and analyzing the technicaloperating procedures, we observed that the geomorphological features as well as the drainage pattern are the result of the conjunction of structural control, neotectonics and regional climatic factors. The possible neotectonic influence is evidenced by means of the tilted and scaled blocks and by means of the drainage network, through the abrupt inflexion of some river courses and right-lined channels. The climatic factors are mainly responsible for the denudational processes and for the erosive features, when associated with anthropic actions. With relation to land occupation and use, we noticed that the transgression of current legislation (Florest Code, 1965) is a common practice; areas with declivity superior to 12% as well as those very close to the river courses are occupied mainly with sugar cane crops. / Com o apoio de índices morfométricos, o presente trabalho teve como objetivo caracterizar a geomorfologia da área correspondente à Folha Alhandra 1:25.000, localizada predominantemente nos Tabuleiros Litorâneos esculpidos na maior parte pelos sedimentos mal consolidados da Formação Barreiras. Esta geomorfologia encontra-se associada aos demais elementos do meio físico com os quais mantém interação mútua. Além disto, este trabalho buscou feições que evidenciem a ação da neotectônica na configuração do relevo e no arranjo da rede de drenagem atual Ainda, foram verificadas as formas de ocupação e uso da terra, avaliando quanto ao cumprimento da legislação vigente. Nesse sentido, fez-se o levantamento bibliográfico para a descrição geral do tema e para a caracterização no que diz respeito aos aspectos geomorfológicos, geológicos, pedológicos, climáticos, da vegetação natural e da hidrografia. Percebendo a importância das geotecnologias, procurou-se utilizá-las para descrever a área com mais precisão, por meio dos produtos cartográficos produzidos. A partir das curvas de nível extraídas da Folha Alhandra e com o auxílio do SPRING 5.1.7, confeccionaram-se as cartas temáticas: hipsométrica, clinográfica, geomorfológica e ainda com o apoio do software referido, de imagens de satélites e de trabalhos de campo, produziuse a carta de ocupação e uso da terra. As duas primeiras possibilitaram mensurar o modelado, o que deu subsídio para analisar as formas de ocupação e uso da terra, sintetizadas tanto na carta de nome homônimo, como na carta de ocupação e uso da terra irregular quanto à declividade, a qual foi construída a partir da sobreposição das cartas clinográfica e de ocupação e uso da terra. Já a carta geomorfológica permitiu estabelecer a ordem cronológica (tempo geológico), partindo da formação mais antiga para as formas atuais. Também se construíram perfis topográficos utilizando o Microsoft Office Excel 2007 para observar detalhes da variação do terreno. Por entender que a geomorfologia está diretamente vinculada à pedologia, fizeram-se análises laboratoriais (pH, densidade do solo, densidade das partículas e granulometria). Por fim, para averiguar a rede de drenagem foram confeccionados os índices Relação Declividade-Extensão (RDE) e densidade de drenagem (Dd), tendo como suporte o software SPRING 5.1.7. O primeiro foi aplicado com intuito de verificar a influência da neotectônica, correlacionando os resultados com a morfologia do relevo. O segundo teve como finalidade identificar pontos suscetíveis a processos erosivos e índices relacionados à produção e ao transporte de sedimentos, provenientes dos interflúvios. Aplicados e analisados todos os procedimentos técnico-operacionais pode-se perceber que as feições geomorfológicas, bem como o arranjo da drenagem atual são resultados da conjunção do controle estrutural, da neotectônica e dos fatores climáticos regionais. A possível influência neotectônica é evidenciada por meio de blocos basculados e escalonados e, na rede de drenagem, por intermédio da inflexão brusca de alguns cursos e de canais retilíneos. Os fatores climáticos são responsáveis, principalmente, pelos processos denudacionais e pelas feições erosivas atestadas, principalmente quando associados às ações antrópicas. Com relação à ocupação e ao uso da terra, percebeu-se que o descumprimento às leis vigentes (Código Florestal, 1965) é prática comum; áreas com declividades superiores a 12%, bem como aquelas muito próximas dos cursos dos rios estão ocupadas principalmente com a monocultura da cana-de-açúcar.
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Evoluation géomorphologique des ravins de l'Artois et du Pays de Thelle (Bassin parisien) / Geomorphological evolution of the ravines of Artois and the Pays de Thelle (Paris basin)

Bochi, Lara 03 December 2014 (has links)
En raison de son importance comme source de sédiments et de sa capacité à modifier l'eau et la connectivité des sédiments lors de pluies intenses, en particulier dans les terres cultivées, le ravinement a besoin d'être mieux compris afin de pouvoir le gérer et atténuer ses effets. Le Pays de Thelle et l'Artois sont les deux régions du Bassin parisien qui concentrent le plus grand nombre de ravins, or les études sur les processus de ravinement ainsi que les tentatives de modélisation restent rares. En utilisant l'analyse morphométrique et l'étude des dépôts conservés à l'aval des incisions, la recherche vise à déterminer quelles sont les variables du système contrôlant de telles incisions, et à reconstituer les étapes de la morphogenèse de ces incisions et les risques qu'elles représentent aujourd'hui. Les ravins se développent là où l'aire drainée et la pente sont suffisantes pour que l'écoulement concentré puisse éroder, on les trouve souvent au niveau de rupture de pente. La mesure des volumes érodés et accumulés montre que l'érosion l'emporte largement sur le dépôt.Les ravins ont enregistré plusieurs phases d'incision dont l'importance s'explique par la conjonction de précipitations exceptionnelles, de fortes pressions anthropiques (défrichements et mise en culture) et de phénomènes tectoniques (soulèvement lent des axes anticlinaux du Bray et de l'Artois). Ces ravins sont des formes fluviatiles, mais la néotectonique joue un rôle essentiel dans le Pays de Thelle, alors qu'en Artois ce sont plutôt les phénomènes karstiques qui l'emportent. Le boisement récent des ravins freine l'incision, mais n'empêche pas l'érosion régressive de faire reculer les têtes de ravins et les risques d'inondations et de coulées boueuses menacent toujours les villages situés à l'aval immédiat de ces ravins / Because of its importance as a source of sediment and its capacity to change the water and the connectivity of sediments during intense rainfall, particularly in the cultivated lands, the gullies have need to be better understood for being able to manage them and mitigate its effects. The Pays de Thelle and Artois are the two regions of the Parisian Basin in which the largest number of ravines is concentrated ; however the studies about the processes of gullies and the attempts of modeling remain rare. Using the morphometric analysis and the study of the preserved deposits in the downstream of the incisions, the research aims to determine which are the variables of the controlling system such incisions, and to reconstruct the morphogenesis stages of these incisions and the risks they represent today. Ravines are occurring where the area draining and the slope are sufficient to make concentrated flow that can erode, they are often found at the level of slope's breakdown. The measurement of the volumes which have been eroded and accumulated shows that the erosion wins largely on the depot. The ravines have recorded several phases of incision in which the importance is explained by the conjunction of exceptional rainfall, strong anthropogenic pressures (land clearing and cultivation) and tectonic phenomena (uprising slow anticlinal axes of Bray and Artois). These ravines are fluvial forms, but the Neotectonic plays an essential role in the Pays de Thelle, whereas it is rather the karst phenomena which prevail in Artois. The recent afforestation of ravines slows the incision, but does not prevent the regressive erosion to roll back the heads of gullies and the risks of floods and mudslides muddy still threaten the villages located immediately downstream of these ravines

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