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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

Sedimentação na bacia do Pantanal Mato-Grossense, Centro-Oeste do Brasil /

Assine, Mario Luis. January 2003 (has links)
Resumo: O Pantanal é uma bacia sedimentar quaternária localizada na Bacia do Alto Rio Paraguai, na Região Centro-Oeste do Brasil. A sucessão estratigráfica mostra afinamento textural para o topo e preenchimento essencialmente siliciclástico. O trato de sistemas deposicionais é composto por uma planície fluvial meandrante como sistema distal de vários leques aluviais dominados por rios, dos quais o mais notável é o megaleque do rio Taquari. Na paisagem atual há muitas feições geomórficas herdadas de diferentes climas, que produziram registros de uma sucessão de eventos do Pleistoceno ao Holoceno. A geometria original de vários leques aluviais de rios entrelaçados está preservada como formas reliquiares, sendo facilmente reconhecíveis em imagens de satélite, onde são visíveis paleocanais distributários. Processos eólicos foram ativos em alguns lobos abandonados, enquanto outros lobos eram construídos, tendo sido provavelmente mais efetivos durante o período de máximo glacial. Lagoas bordejadas por dunas de areia em meia-lua, originalmente depressões de deflação, são formas eólicas reliquiares na paisagem do Pantanal. A paisagem tem continuamente mudado desde o fim do Pleistoceno, numa adaptação a um ambiente mais úmido e quente, dominante no Holoceno. O surgimento das modernas terras úmidas (wetlands) ocorreu na transição do Pleistoceno para o Holoceno, assim como a individualização dos sistemas lacustrinos. O Pantanal, como hoje o conhecemos, é uma vasta planície com gradiente topográfico muito baixo e de lento escoamento superficial das águas, por isso sazonalmente inundável nos meses de verão e outono. Apesar das mudanças climáticas, os leques aluviais permaneceram sistemas deposicionais ativos. Novos lobos foram formados ao mesmo tempo em que lobos antigos foram submetidos a processos de pedogênese e erosão por sistemas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Pantanal is a Quaternary sedimentary basin located at the left margin of the Upper Paraguay River, west-central Brazil. Basin infilling was mainly by siliciclastic sediments and the stratigraphic succession exhibits an overall finingupward pattern. The depositional system tract is composed by a large meandering fluvial plain and several marginal alluvial fans, being the Taquari megafan the most striking feature. The present landscape is a complex tropical wetland, with geomorphic features derived from the present conditions and other inherited from successive Pleistocene and Holocene climates. During the Pleistocene, the sedimentary environment was dominated by braided alluvial fans, the original geometry of which is preserved as relict forms, permitting remarkable patterns of distributary paleochannels to be easily recognized in satellite images. Eolian processes were active in some abandoned lobes, contemporaneously with sedimentation in active fan lobes. Closed ponds bordered by lunette sand dunes, originally salt pans produced by eolian deflation, are relict eolian landforms in the Pantanal landscape. Eolian processes were probably more effective at the glacial maximum. Landscape has been changing in the Pantanal area since the end of the Pleistocene in adaptation to a more humid and warmer environment prevailing during Holocene. Initiation of the modern wetland has occurred during the Pleistocene / Holocene transition, with the change to a more humid climate and the individualization of lacustrine systems. The modern Pantanal wetland is a vast expanse of poorly drained lowlands that experiences annual flooding from summer to fall months. Although climatic fluctuations have occurred during all the Holocene, the alluvial fans have remained active depositional systems and lobes were formed by progradation and abandonment. Abandoned lobes were subjected... (Complete abstract click electronic address below)
2

Sedimentological re-interpretation of the early cretaceous oil reservoir in the Northern Bredasdorp Basin, offshore South Africa

Asiashu, Mudau January 2015 (has links)
>Magister Scientiae - MSc / This study was aimed at determining the sedimentary environment, its evolution and facies areal distribution of the Upper Shallow Marine (USM, Late Valanginian). The study was conducted in wells E-S1, F-AH4 and E-W1 in the Bredasdorp basin between E-M and F-AH fields, located in a basinwards transect roughly transverse to the palaeocoast. The wells were studied by logging all the cores in detail between the chosen intervals, followed by facies analysis. Each core log was tied with its respective gamma ray and resistivity well logs. The logs were then correlated based on their log signatures, trends and facies interpretation. The Gamma ray logs show a fining-upwards and coarsening-upwards trend (“hour-glass shape”) in E-S1 and F-AH4 while in E-W1 it shows more accommodation space. These trends are believed to have been influenced by relative sea level changes, such as transgression and regression. Facies analysis identified seven facies in the study area: Facies A, B, C, D, E, F and G. Facies A, B and C were interpreted as fair-weather and storm deposits of the offshore-transition zone, shoreface and foreshore respectively. Facies D was considered as lagoonal mud deposits, while Facies E and F were interpreted as tidal channel and tidal bar deposits respectively. Finally Facies G was considered as fluvial channel deposits. The facies inferred that the sedimentary environment of the study area is a wave-dominated estuary or an Island-bar lagoon system. This led to the production of a conceptual model showing the possible locations for the three wells in the Island bar-lagoon system. The conceptual model inferred the previous findings from PGS (1999) report, that the Upper Shallow Marine beds were deposited in a tidal/estuarine to shoreface setting. This model also supports the findings of Magobiyane (2014), which proposed a wave-dominated estuary for the Upper Shallow Marine reservoir between E-M and F-AH fields, located west of the study area.
3

Ichnofosilie spodního paleozoika Železných hor / Ichnofossils from the Lower Palaeozoic of the Železné hory Mts.

Doucek, Jan January 2010 (has links)
On five key sites of the Lower Palaeozoic of the Železné hory Mountains (Bačalský rybník, Bačalský mlýn, Palác, Rabštejn and Deblov) the detailed research involving the compilation of schematic lithostratigraphic profiles (exluding site Deblov) was conducted. Individuals of ichnotaxa Zoophycos that have maximum Middle Cambrian age were described on the site Palác. This is the third oldest finding in the world. Ichnotaxa Zoophycos was further described on the site Bačalský rybník, where they are exposed quartz siltstones, the equivalent of the Dobrotiv of the Barrandian area. Ichnofossils abundant in the study area are Skolithos, Pragichnus, to a lesser extend Phycodes and Monocraterion. Skolithos on the site Rabštejn occurs in extreme size (until 90 cm). On the site Deblov community of Skolitos ichnofacies on the area measuring hundreds of square meters were described. There was also performed ichnological imaging which showed proportional representation of each ichnotaxa. Study samples for microprobe showed differences in structure and chemistry of ichnofabrics up filling and surrounding environment.
4

Interpretace georadarových měření s využitím kombinovaného geoelektrického průzkumu / GPR data interpretation with use of a combined geoelectrical survey

Široký, Jakub January 2016 (has links)
GPR data interpretation is often difficult due to complex geological environments, reflections ambiguity and time-depth conversion uncertainty. Thanks to the geophysical fields interoperability it is possible to compare results of related survey methods. Radargrams from three model sites were processed and interpreted in an usual way to uniformly amplify all recorded reflections. Results were compared with ERT and EM (DEMP) data within integrated interpretation. GPR data interpretation was extended and new geological and geomorphological interpretations were uncovered. The GPR processing sequence was modified and simplified following outcomes from the integrated interpretation to ease different methods results comparison. Adapting a velocity model to precise time- depth conversion hasn't showed improvements. Key words: ground penetrating radar, electrical resistivity tomography, dipole electromagnetic profiling, integrated interpretation, integrated inversion, GPR processing optimization, sedimentary environment, velocity model

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