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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.
11

Investigating Time Series Shoreline Changes By Integration Of Remote Sensing And Geographical Information Systems

Fulat, Alper Ihsan 01 December 2005 (has links) (PDF)
Spatial analyses of shoreline recession and accretion, and future shoreline position predictions in coastal countries have considerable importance due to engineering, planning, management and environmental concerns. In spite of this importance, there are only a few studies in Turkey. The aim of this thesis are to determine the shoreline rate-of-change of B&uuml / y&uuml / k Menderes Delta, by geographical information systems for the last fifty-year period, in order to approximate future shoreline position of B&uuml / y&uuml / k Menderes Delta shoreline, and to evaluate appropriate models while predicting the future shoreline position. To achieve the purpose of the study time series shoreline position data is extracted from three sets of topographic maps belonging to 1954-1957, 1977-1978 and 1993 aerial photographs and two sets of high resolution satellite imageries (January 2002 Ikonos, August 2004 QuickBird). Then Coastal script of TNTMips, which uses some statistical shoreline analyses methods, that are End Point Rate (EPR), Average of Rates (AOR), Linear Regression (LR) and Jackknifing (JK) is edited so that it can locate the future shoreline positions on the map. Suitable baselines are created and appropriate transect intervals are decided to analyze the shoreline. Finally, some additional analyses that are Backward Analysis and Oscillation Analysis are done to obtain most suitable future shoreline position with rate-of-changes. The results showed that, shorelines having different geomorphologic characteristics needed to be analyzed separately and the linear methods to model the future shoreline position differ from one geomorphologic region to another.
12

Sequence stratigraphic characterisation of petroleum reservoirs in Block 11b/12b of the Southern Outeniqua Basin

Nfor, Nformi Emmanuel January 2011 (has links)
Magister Scientiae - MSc / The main purpose of this study was to identify and characterize the various sand prone depositional facies in the deepwater Southern Outeniqua Basin which generally tend to form during lowstand (marine regression) conditions producing progradational facies. It made use of sequence stratigraphy and turbidite facies models to predict the probable location of deepwater reservoirs in the undrilled Southern Outeniqua Basin using data from basin margin Pletmos Basin and the deepwater Southern Outeniqua Basin. Basin margin depositional packages were correlated in time and space with deepwater packages. It was an attempt at bridging the gap between process-related studies of sedimentary rocks and the more traditional economic geology f commercial deposits of petroleum using prevailing state-of-the-art in basin analysis. It enabled the most realistic reconstructions of genetic stratigraphy and offered the greatest application in exploration. Sequence stratigraphic analysis and interpretation of seismics, well logs, cores and biostratigraphic data was carried out providing a chronostratigraphic framework of the study area within which seismic facies analysis done. Nine (9) seismic lines that span the shallow/basin margin Pletmos basin into the undrilled deepwater Southern Outeniqua basin were analysed and interpreted and the relevant seismic geometries were captured. Four (4) turbidite depositional elements were identified from the seismic lines: channel, overbank deposits, haotic deposits and basin plain (basin floor fan) deposits. These were identified from the relevant seismic geometries (geometric attributes) observed on the 2D seismic lines. Thinning attributes, unconformity attributes and seismic facies attributes were observed from the seismic lines. This was preceded by basic structural analyses and interpretation of the seismic lines. according to the structural analysis and interpretation, deposition trended NW-SE and NNW-SSE as we go deepwater into the Southern Outeniqua basin. Well logs from six (6) of the interpreted wells indicated depositional channel fill as well as basin floor fans. This was identified in well Ga-V1 and Ga-S1 respectively. A bell and crescent shape gamma ray log signature was observed in well Ga-V1 indicating a fining up sequence as the channel was abandoned while an isolated massive mound-shape gamma ray log signature was observed in Ga-S1 indicating basin plain well-sorted sands. Core analyses and interpretation from two southern-most wells revealed three (3) facies which were derived based on Walker‘s 1978, turbidite facies. The observed facies were: sandstone, sand/shale and shale facies. Sequence stratigraphic characterisation of petroleum reservoirs in block 11b/12b of the Southern Outeniqua Basin. Cores of well Ga-V1 displayed fine-grained alternations of thin sandstone beds and shales belonging to the thin-bedded turbidite facies. This is typical of levees of the upper fan channel but could easily be confused with similar facies on the basin plain. According to Walker, 1978 such facies form under conditions of active fan progradation. Ga-S1 cores displayed not only classic turbidite facies where there was alternating sand and shale sections but showed thick uninterrupted sections of clean sands. This is typical of basin plain deposits. Only one well had biostratigraphic data though being very limited in content. This data revealed particular depth sections and stratigraphic sections as having medium to fast depositional rates. Such rates are characteristic of turbidite deposition from turbidity currents. This study as well as a complementary study by Carvajal et al., 2009 revealed that the Southern Outeniqua basin is a sand-prone basin with many progradational sequences in which tectonics and sediment supply rate have been significant factors (amongst others such as sea level change) in the formation of these deepwater sequences. In conclusion, the Southern Outeniqua basin was hereby seen as having a viable and unexplored petroleum system existing in this sand prone untested world class. / South Africa
13

[en] PROJECTIONS OF FUTURE SCENARIOS OF SHORELINE BEHAVIOR: ATAFONA AND GRUSSAÍ BEACH (RJ) BASED ON THE DYNAMIC TREND OBSERVED IN THE PERIOD FROM 1954 TO 2022 / [pt] PROJEÇÕES DE CENÁRIOS FUTUROS DE COMPORTAMENTO DA LINHA DE COSTA ENTRE ATAFONA E GRUSSAÍ (SÃO JOÃO DA BARRA, RJ) A PARTIR DA TENDÊNCIA DINÂMICA OBSERVADA NO PERÍODO DE 1954 A 2022

ISABELLE AFONSO VIEIRA DE SOUZA 14 November 2023 (has links)
[pt] A zona costeira é caracterizada por possuir certa fragilidade devido a sua complexa dinâmica ambiental, que é diretamente correspondente a interação dos agentes continentais e marinhos que, nem sempre, atuam em equilíbrio. Sendo assim, a intensa ocupação humana nas regiões costeiras, muitas vezes de forma desordenada, vem intensificando este desequilíbrio gerando consequências e impactos, usualmente negativos, ao ambiente costeiro e a população que habita a beira mar. Neste contexto, o presente trabalho compreende a realização do monitoramento continuado para o trecho do litoral entre Atafona e Grussaí, localizado em São João da Barra, litoral norte fluminense, através da projeção de cenários futuros de comportamento da linha de costa, para a temporalidade de 5, 10, 15, 20, 25 e 30 anos, baseados na tendência de comportamento de diversos pontos fixos observado através da dinâmica mapeada sobre séries históricas de fotografias aéreas e imagens de satélite nos últimos 68 anos. Os resultados encontrados para os cenários futuros mostram a retrogradação da linha de costa a uma velocidade média de -2,78m/ano na região afetada pelo processo erosivo e uma progradação de +2,51 m/ano onde ocorre predominantemente o processo de acreção. Mantendo-se a dinâmica atualmente delineada, o cenário futuro para os próximos 30 anos aponta que a região próxima ao pontal de Atafona continuará sendo a mais afetada pela perda de terreno costeiro em resposta à dinâmica erosiva, onde a maior taxa linear encontrada é de -161,10m a partir da atual linha de costa; na praia de Grussaí, a incorporação de sedimentos devido o processo de acreção tende a produzir uma progradação da linha de costa atual de cerca de +127,10m. / [en] The coastal zone is characterized by having a certain fragility due to its complex environmental dynamics, which is directly corresponding to the interaction of continental and marine agents that, not always, act in balance. Thus, an intense human occupation in coastal regions, often in a disorderly way, has intensified this imbalance, generating consequences and impacts, usually negative, to the coastal environment and a population that inhabits the seashore. In this context, the present work comprises the carrying out of continuous monitoring for the stretch of coast between Atafona and Grussaí, examination in São João da Barra, Rio do Janeiro s north coast, through the projection of future behavior scenarios. coastline, for the temporality of 5, 10, 15, 20, 25 and 30 years, based on the behavior trend of each fixed point observed through the dynamics mapped in the last 68 years. The results found for future scenarios show the displacement of the coastline at an average speed of -2.78 m/year in the region affected by the erosion process and +2.51 m/year where the progradation process occurs. Keeping the currently outlined dynamics, the future scenario for +30 years points out that the region close to the Atafona point will continue to be the most affected by the erosion dynamics, where the highest linear rate found is -161.10m from the current line of coastline in the region, while at Grussaí beach, the progressive process will have added +127.10m to the current coastline.
14

Dynamique du trait de côte sur les littoraux sableux de la Mauritanie à la Guinée-Bissau (Afrique de l'Ouest) : Approches régionale et locale par photo-interprétation, traitement d'images et analyse de cartes anciennes

Faye, Ibrahima 15 February 2010 (has links) (PDF)
Ce mémoire sur l'évolution des littoraux sableux de la Mauritanie à la Guinée-Bissau est le fruit d'une recherche doctorale menée dans le cadre du projet «Bilan prospectif des changements à long terme de l'environnement côtier d'Afrique de l'Ouest», composante recherche du Programme Régional de Conservation des Zones Côtières et Marines en Afrique de l'Ouest (PRCM). Il s'envisageait à deux échelles spatiales (régionale et locale) et avait pour objectif de mettre en évidence et de mesurer les phénomènes d'érosion et d'accumulation intervenus depuis plusieurs décennies sur les côtes sableuses de la Mauritanie à la Guinée-Bissau. A l'échelle régionale, la superposition des lignes instantanées de rivage ou des limites de végétation extraites d'images Landsat multidates par équidensitométrie ou par classification avec l'ISODATA indique en dépit d'une érosion ponctuelle, une tendance à la progradation des formes très mobiles telles que les pointes des flèches, des petites îles et cordons sableux isolant des mangroves dans les systèmes estuariens du Sénégal à la Guinée-Bissau. L'analyse locale porte sur quatre sites répartis sur le littoral sénégalo-mauritanien (Nouakchott, Ndiago – Saint-Louis, Bargny – Yène-sur-mer, Mbour – Pointe Sarène) et s'étendant sur 67 km environ. Fondée essentiellement sur le traitement numérique et l'interprétation d'images aériennes au sein d'un SIG, l'étude de l'évolution spatio-temporelle de la position des marqueurs sélectionnés comme traits de côte (ligne de pleines mers ou limite supérieure de la plage) révèle une érosion sur 47 km (70 %) de côte et une progradation sur 20 km (30 %).
15

Controls on sedimentary processes and 3D stratigraphic architecture of a mid-Miocene to recent, mixed carbonate-siliciclastic continental margin : northwest shelf of Australia

Sanchez, Carla Maria, 1978- 11 July 2012 (has links)
Determining the relative importance of processes that control the generation and preservation of continental margin stratigraphy is fundamental to deciphering the history of geologic, climatic and oceanographic forcing imprinted on their sedimentary record. The Northern Carnarvon Basin (NCB) of the North West Shelf of Australia has been a site of passive margin sedimentation throughout the Neogene. Cool-water carbonate sedimentation dominated during the early-middle Miocene, quartz-rich siliciclastics prograded over the shelf during the late-middle Miocene, and carbonate sedimentation resumed in the Pliocene. Middle Miocene to Pliocene siliciclastics were deposited as clinoform sets interpreted as delta lobes primarily based on their plan-view morphology and their relief of 40-100 m. Shelf-edge trajectory analysis suggests that part of this stratigraphic succession was built during a long-term, third order, regressive phase, producing shelf-edge deltas, followed by an aggradational episode. These trends appear to correlate with third-order global eustatic cycles. Slope incisions were already conspicuous on the slope before deltas reached the shelf-break. Nevertheless, slope gullies immediately downdip from the shelf-edge deltas are wider and deeper (>1 km wide, ~100 m deep) than coeval incisions that are laterally displaced from the deltaic depocenter (~0.7 km wide, ~25 m deep). This change in gully morphology is likely the result of greater erosion by sediment gravity flows sourced from shelf-edge deltas. Total late-middle to late Miocene margin progradation increased almost three times from 13 km in the southwest to 34 km in the northeast, where shelf-edge deltas were concentrated. Flat-topped carbonate platforms seem to have initiated on subtle antecedent topographic highs resulting from these deltaic lobes. A reduction of siliciclastic supply to the outer paleo-shelf during the Pliocene combined with the onset of a southwestward-flowing, warm-water Leeuwin Current (LC) most likely controlled the initiation of these carbonate platforms. These platforms display marked asymmetry, likely caused by an ancestral LC, which created higher-angle, upcurrent platform margins, and lower-angle, downcurrent clinoforms. The along-strike long-term migration trend of the platforms could be the result of differential subsidence. These platforms constitute the first widespread accumulation of photozoan carbonates in the Northern Carnarvon Basin. They became extinct after the mid-Pleistocene when the LC weakened or became more seasonal. / text
16

Processos organo-sedimentares da Lagoa Salgada (RJ, Brasil) durante os últimos 7000 anos A.P. : implicações paleoambientais

Blanco, Angélica Maria 22 March 2016 (has links)
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-03-22T19:15:25Z No. of bitstreams: 1 Dissertação Mestrado_ Angélica Blanco_FINALCORRIGIDA.pdf: 3674860 bytes, checksum: 71cb912a535da66b5045cc37b27095b1 (MD5) / Made available in DSpace on 2016-03-22T19:15:25Z (GMT). No. of bitstreams: 1 Dissertação Mestrado_ Angélica Blanco_FINALCORRIGIDA.pdf: 3674860 bytes, checksum: 71cb912a535da66b5045cc37b27095b1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências-Geoquímica. Niterói, RJ / O desenvolvimento de planícies costeiras e a evolução de ambientes deposicionais Fúlviolagunares e depósitos praias deu origem a diversas lagoas ao longo da costa do Estado do Rio de Janeiro. Os sistemas lagunares estiveram influenciados pelas variações do nível do mar com sedimentos oriundos de diversas fontes. Como consequência das flutuações do nível do mar, os sistemas lagunares formados apresentaram características especiais como mistura de águas continentais e marinhas, geralmente com alta salinidade. Este trabalho caracteriza a sedimentação do paleoambiente da lagoa Salgada com uso de isótopos 13C, 15N, do 14C e C:N na matéria orgânica (MO) do testemunho S15. Foi construído um modelo cronológico, através de regressão linear resultando em um período compreendido entre 6.300 e 1.300 anos cal. AP. Devido à complexidade nas interpretações paleoambientais e sedimentológicas de ambientes de planícies deltáicas, assim como a identificação das fontes de MO, os processos de sedimentação foram analisados através da litologia e história evolutiva do lago. O testemunho S-15 foi dividido em três unidades (I, II e III) e nove sub-unidades litológicas (A, B, C, D, E, F, G, H e I) de modo a correlacionar os sedimentos e a MO e assim compreender os processos de sedimentação na lagoa nos últimos 7.000 anos. Os sedimentos são siliciclásticos com fases intercaladas de lama arenosa e lama síltico-argilosa, isto sugere uma sedimentação lacustre num sistema com variações de energia. A geoquímica isotópica do testemunho S-15 mostrou pouca variação ao longo da sucessão sedimentar. A variabilidade dos valores do 13C e do 15N ao longo do testemunho sugere três fases de sedimentação orgânica (fluvial, estuarina e lagunar) devido à transição do ambiente marinho a lagunar, influenciado pela evolução deltáica. Os valores C:N sugerem mistura de fontes de MO alóctone e autóctone (plantas terrestres C3, bactérias e fitoplâncton). O clima semiárido na região, em consequência da ressurgência costeira e fechamento do sistema lagunar, favoreceu a precipitação de sais e carbonatos uma vez que a lagoa ficou isolada na planície costeira. Assim, a geoquímica e os processos de sedimentação mudaram gerando condições específicas para o desenvolvimento de tapetes microbiais e, posteriormente para o topo da sucessão, os estromatólitos. / The development of coastal plains and the evolution of fluvial-lagoonal depositional environments and beach deposits gave rise to several lakes along the Rio de Janeiro State coast. The lagoonal systems were influenced by the sea level variations with sediments from different sources. As a consequence of the fluctuations in sea levels, the lagoonal systems presented special features as a mixture of continental and marine waters, usually with high salinity. This study characterizes the sedimentation of the paleo-environment of Salgada lake, using 13C, 15N isotopes, 14C and C:N in the organic matter (OM ) of the core S-15. It was constructed a chronological model based on linear regression resulting in a period between 6.300 and 1.300 yrs cal. BP. Due to the complexity on paleoenvironmental and sedimentological interpretations in delta plain environment as well the identification of OM sources, the sedimentation processes were analyzed trough the lithology and evolutionary history of the lake. The S-15 core was divided into three units (I , II, and III) and nine lithological sub-units (A, B, C , D, E , F, G , H and I) in order to correlate the sediments and the OM and therefore to understand the lake sedimentation processes in the last 7.000 years. The sediments are siliciclastic with intercalated phases of sandy mud- and clay silt mud -. This suggests a lacustrine system with variations in energy. The isotopic geochemistry of S- 15 core showed little variation throughout the sedimentary succession. The variability of 13C and 15N values along the core suggests three phases of organic sedimentation (fluvial, estuarine and lagoonal) due to the transition from the marine to lagoonal environment, influenced by the deltaic evolution. The C:N values suggests mixing sources of allochthonous and autochthonous OM (C3 terrestrial plants, bacteria and phytoplankton). The semiarid weather in the region, as a consequence of coastal upwelling, and closure of the lake system favored the precipitation of salts and carbonates, since the lagoon was isolated in the coastal plain. Therefore the geochemistry and the sedimentation processes changed generating specific conditions for the development of microbial mats and further, to the top of the succession, the stromatolites.
17

Patterns of Coal Sedimentation in the Ipswich Basin Southeast Queensland

Chern, Peter Kyaw Zaw Naing January 2004 (has links)
The intermontane Ipswich Basin, which is situated 30km south-west of Brisbane, contains coal measures formed in the Late Triassic Epoch following a barren non-depositional period. Coal, tuff, and basalt were deposited along with fluvial dominated sediments. The Ipswich Coal Measures mark the resumption of deposition in eastern Australia after the coal hiatus associated with a series of intense tectonic activity in Gondwanaland during the Permo-Triassic interval. A transtensional tectonic movement at the end of the Middle Triassic deformed the Toogalawah Group before extension led to the formation of the Carnian Ipswich Coal Measures in the east. The Ipswich Coal Measures comprise the Brassall and Kholo Subgroups. The Blackstone Formation, which forms the upper unit of the Brassall Subgroup, contains seven major coal seams. The lower unit of the Brassall Subgroup, the Tivoli Formation, consists of sixteen stratigraphically significant coal seams. The typical thickness of the Blackstone Formation is 240m and the Tivoli Formation is about 500m. The coal seams of the Ipswich Basin differ considerably from those of other continental Triassic basins. However, the coal geology has previously attracted little academic attention and the remaining exposures of the Ipswich coalfield are rapidly disappearing now that mining has ceased. The primary aim of this project was to study the patterns of coal sedimentation and the response of coal seam characteristics to changing depositional environments. The coal accumulated as a peat-mire in an alluvial plain with meandering channel systems. Two types of peat-mire expansion occurred in the basin. Peat-mire aggradation, which is a replacement of water body by the peatmire, was initiated by tectonic subsidence. This type of peat-mire expansion is known as terrestrialisation. It formed thick but laterally limited coal seams in the basin. Whereas, peat-mire progradation was related to paludification and produced widespread coal accumulation in the basin. The coal seams were separated into three main groups based on the mean seam thickness and aerial distribution of one-meter and four-meter thickness contour intervals. Group 1 seams within the one-meter thickness interval are up to 15,000m2 in area, and seams within the four-meter interval have an aerial extent of up to 10,000m2. Group 1A contains the oldest seam with numerous intraseam clastic bands and shows a very high thickness to area ratio, which indicates high subsidence rates. Group 1B seams have moderately high thickness to area ratios. The lower clastic influx and slower subsidence rates favoured peat-mire aggradation. The Group 1A seam is relatively more widespread in aerial extent than seams from Group 1B. Group 1C seams have low mean thicknesses and small areas, suggesting short-lived peat-mires as a result of high clastic influx. Group 2 seams arebetween 15,000 and 35,000m2 in area within the one-meter interval, and between 5,000 and 10,000m2 within the four-meter interval. They have moderately high area to thickness ratios, indicating that peat-mire expansion occurred due to progressively shallower accommodation and a rising groundwater table. Group 3 seams, which have aerial extents from 35,000 to 45,000m2 within the one-meter thickness contour interval and from 10,000 to 25,000m2 within the four-meter interval, show high aerial extent to thickness ratios. They were deposited in quiet depositional environments that favoured prolonged existence of peat-mires. Group 3 seams are all relatively young whereas most Group 1 seams are relatively old seams. All the major fault systems, F1, F2 and F3, trend northwest-southeast. Apart from the West Ipswich Fault (F3), the F1 and F2 systems are broad Palaeozoic basement structures and thus they may not have had a direct influence on the formation of the much younger coal measures. However, the sedimentation patterns appear to relate to these major fault systems. Depocentres of earlier seams in the Tivoli Formation were restricted to the northern part of the basin, marked by the F1 system. A major depocentre shift occurred before the end of the deposition of the Tivoli Formation as a result of subsidence in the south that conformed to the F2 system configuration. The Blackstone Formation depocentres shifted to the east (Depocentre 1) and west (Depocentre 2) simultaneously. This depocentre shift was associated with the flexural subsidence produced by the rejuvenation of the West Ipswich Fault. Coal accumulation mainly occurred in Depocentre 1. Two types of seam splitting occurred in the Ipswich Basin. Sedimentary splitting or autosedimentation was produced by frequent influx of clastic sediments. The fluvial dominant depositional environments created the random distribution of small seam splits. However, the coincidence of seam splits and depocentres found in some of the seams suggests tectonic splitting. Furthermore, the progressive splitting pattern, which displays seam splits overlapping, was associated with continued basin subsidence. The tectonic splitting pattern is more dominant in the Ipswich Basin. Alternating bright bands shown in the brightness profiles are a result of oscillating water cover in the peat-mire. Moderate groundwater level, which was maintained during the development of the peat, reduced the possibility of salinisation and drowning of the peat swamp. On the other hand, a slow continuous rise of the groundwater table, that kept pace with the vertical growth of peat, prevented excessive oxidation of peat. Ipswich coal is bright due to its high vitrinite content. The cutinite content is also high because the dominant flora was pteridosperms of Dicroidium assemblage containing waxy and thick cuticles. Petrographic study revealed that the depositional environment was telmatic with bog forest formed under ombrotrophic to mesotrophic hydrological conditions. The high preservation of woody or structured macerals such as telovitrinite and semifusinite indicates that coal is autochthonous. The high mineral matter content in coal is possibly due to the frequent influx of clastic and volcanic sediments. The Ipswich Basin is part of a much larger Triassic basin extending to Nymboida in New South Wales. Little is known of the coal as it lacks exposures. It is apparently thin to absent except in places like Ipswich and Nymboida. This study suggests that the dominant control on depocentres of thick coal at Ipswich has been the tectonism. Fluvial incursions and volcanism were superimposed on this.

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