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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.
51

Arquitetura deposicional de um sistema de lençol de areia eólica : a Bacia Bauru na região de Marília (SP) / Depositional architecture of an aeolian sand sheet system : the Bauru basin on Marília (SP)

Prandi, Pedro Lifter Rodrigues, 1985- 03 September 2012 (has links)
Orientador: Giorgio Basilici / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-21T07:38:10Z (GMT). No. of bitstreams: 1 Prandi_PedroLifterRodrigues_M.pdf: 6770707 bytes, checksum: cf2520ff00d4079bf88ddac4cccd8e0b (MD5) Previous issue date: 2012 / Resumo: O principal objetivo deste trabalho é a caracterização estratigráfica da bacia Bauru nas proximidades do município de Marília (SP) através da análise das diferentes litofácies e superfícies limitantes de diversas escalas. O trabalho inclui também a análise dos paleossolos como elemento arquitetural, e a geofísica de poços que proporcionaram um maior detalhamento nas análises dos dados de superfície e subsuperfície. Os depósitos na área são interpretados como sucessões de lençóis de areia eólica com forte influência de processos pedogenéticos no topo e depósitos subaquosos na base da sequência. Esta influência ocorre devido a variações no clima. A espessura dos depósitos na área é de aproximadamente 260 metros, como pode ser comprovado pelos dados de perfilagem. As litofácies determinadas para este trabalho foram o arenito com laminação plano paralela, arenito com estruturas de fluxo não canalizado e arenito com estruturas de adesão. Para os paleossolos encontrados foram o Aridisols e o Entisols. Três fases deposicionais são distintas, da base para o topo: 1) A primeira fase deposicional é caracterizada por uma predominância de depósitos eólicos com grande influência do lençol freático aflorante; 2) A segunda fase também predominada por depósitos eólicos, porém mais seca, com pequena influência do lençol e a presença de paleossolos é pequena; 3) A terceira fase, do topo, é caracterizada por uma predominância de processos pedogenéticos ainda de clima árido a semiárido / Abstract: The main objective of this work is the stratigraphic characterization of Bauru basin in the city of Marília (SP) through the analysis of different lithofacies and bounding surfaces of various scales. This work also include an analysis of paleosols as an architectural element, and the analysis of geophysics wells data that provide a better detailed characterization of the surface and subsurface lithology. The deposit on this area is interpreted as eolian sand sheet deposits with strong influence of pedogenetic processes at the top and subaqueous at the bottom of the sequence. This influence occur due to the climate variations. The thickness of the deposit in this area is approximately 260 meters, as proven by the profiling data. The lithofacies determined for this work are: the sandstone with parallel lamination; sandstone with non-channeled flow structures and sandstone with adhesion structures. The palaeosols found was Aridisols and Entisols type. Three deposition phases can be distinguished, from the base to the top: 1) The first phase of the aeolian deposition process is characterized by a predominance of aeolian deposits with highly influence of water table; 2) The second phase is also of aeolian sedimentation but drier than the lower one, it is not so influenced by the water table and that are few paleosols; 3) Third phase, at the top of the deposit, is characterized by pedogenic processes from arid to semiarid climate / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências
52

Etude des propriétés de structuration de matériaux mixtes et fins. Application à l'envasement des systèmes naturels / Study of structuring properties of mixed and fine materials. Multi-scale approach. Application in the mundding of the natural system

Serhal, Saly 19 December 2017 (has links)
Les estuaires sont généralement soumis à des phénomènes de comblement sédimentaires. Dans cette partie des systèmes fluviaux du territoire, l'accumulation des matériaux fins modifie radicalement la morphologie de l'estuaire, et conditionne la présence des espèces animales et végétales et on distingue un impact fort sur le plan économique, social et industriel. Les comblements compliquent la circulation dans les estuaires, compliquent les activités de pêches, de loisirs, modifient les propriétés des écoulements et constituent un facteur risque sur les zones d'habitations voisines. Des solutions temporaires consistent à curer les estuaires et des solutions d'aménagement des estuaires peuvent être envisagées. Néanmoins, il ressort de la littérature un manque important sur la caractérisation des mélanges liquides-solides et sur les mécanismes de structuration. Ce travail s'inscrit dans le contexte de l'étude des mécanismes de structuration des matériaux sédimentaires dans les estuaires afin de mieux comprendre les remplissages des zones estuariennes et surtout d'envisager des solutions durables de « nettoyage » de ces zones. L'estuaire de la Rance est particulièrement ciblé par notre étude. Le but est de donner des éléments de réponse sur le comportement rhéologique des vases naturelles en distinguant les échelles les plus significatives afin de détecter les facteurs structurants qui influencent les paramètres rhéologiques. La rhéologie des sédiments est ainsi étudiée à l'aide du rhéomètre Kinexus, géométrie plan-plan. On a pu alors détecter un comportement visco-plastique Bighamien. L'influence du diamètre moyens et de la fraction volumique solide sur la viscosité et le seuil de la contrainte de cisaillement dynamique du modèle de Bingham sont ainsi analysés. Ensuite, nous avons étudié grâce à des sédiments sans sel et sans matière organique, l'influence de ces deux composés chimiques sur le comportement rhéologiques des sédiments et puis leurs influences sur le vieillissement des sédiments. Une étude statique est également réalisée à l'aide du Va ne test permettant le calcul de la contrainte de cisaillement seuil. •Enfin, une assimilation du piège du Lyvet est réalisée grâce à des colonnes de sédimentation dans des conditions assez proches des conditions naturelles. Un processus de sédimentation-tassement-consolidation sous poids propre est recréé en laboratoire. Les sédiments sont amenés à vieillir cette fois pour des longues durées allant jusqu'à 9 mois. Au terme de périodes de vieillissement retenues, le massif créé est caractérisé depuis l'interface fluide-sédiments. Cela nous a permis d'étudier la répartition granulaire des sédiments après structuration et la variation de la contrainte de cisaillement seuil selon la profondeur de la colonne et la durée du vieillissement. Ce type d'essai est aussi réalisé pour les sédiments sans sel et sans matières organiques. / Estuaries are generally subject of sedimentary filling phenomena that alter their morphology and affect subsequently the economic, social and industrial plans. In this part of the fluvial systems of the territory, the accumulation of fine materials radically modifies the morphology of the estuary, and conditions the presence of animal and plant species and cause a strong impact on the economic, social and industrial. Filling complicates navigation in estuaries, fishing, recreational activities and modifies flow properties and is a risk factor in neighboring housing areas. Temporary solutions consist of cleaning estuaries and estuarine management solutions can be considered. Nevertheless, the literature shows a significant lack of characterization of liquid-solid mixtures and structuring mechanisms. This work is in the context of the study of structuring mechanisms of sedimentary materials in estuaries to better understand the fillings estuarine areas and specially to consider sustainable solutions of "cleansing" of these areas. The Rance estuary is particularly targeted by the study. The aim is to provide answers on the rheological behavior of natural vessels by distinguishing the most significant scales to detect structural factors influencing the rheological parameters. The rheology of the sediments is studied using the Kinexus rheometer, plan-plan geometry. A Bighamien visco-plastic behavior was then detected. The influence of the mean diameter and the solid volume fraction on the viscosity and the threshold of the dynamic shear stress of the Bingham model are thus analyzed. Then, using sediments without salt and organic matter, we studied the influence of these two chemical compounds on the rheological behavior of the sediments and their influence on the aging of the sediments. A static study is also carried out using the Vane test allowing the calculation of the threshold shear stress. Finally, an assimilation of the natural filling phenomenon is achieved in columns under conditions similar to natural conditions. These columns are then filled with natural sediments, washed sediments and sediments free of organic material and left for ages ranging from one week to 9 months. Then, the columns will be disassembled and rheological tests with the Brookfield Rheometer will be performed throughout the depth of the columns as well as measurements of water content and grain size. These tests allow us to study sediment structuring in the long term and also to identify the effect of salt and organic matter on sedimentation.
53

The geology of the Godwan Basin, Eastern Transvaal

Myers, R.E. 05 August 2014 (has links)
M.Sc. (Geology) / Please refer to full text to view abstract
54

Source rock characterization of the organic rich intervals of the Taranaki Basin, Offshore New Zealand

Amansure, Giovanni Ricardo January 2015 (has links)
>Magister Scientiae - MSc / The Taranaki Basin is a large (ca. 330,000 km²) sedimentary basin found along the west coast of the northern island of New Zealand. The basin lies partly onshore but mostly offshore below the broad continental shelf to the west of central North Island. The Taranaki Basin is the first sedimentary basin to be explored in New Zealand and is currently New Zealand’s only hydrocarbon producing basin, with approximately 418 million barrels (MMbbl) of oil and 6190 billion cubic feet (bcf) of gas produced by the end of 2011. Most of New Zealand’s known oil and gas accumulations are geochemically typed to coaly facies of Late Cretaceous and Paleogene ages. The main objective of this thesis is to characterize the source rock quality of the organic rich intervals of the Taranaki Basin, namely, the Wainui Member of the North Cape Formation and the Rakopi Formation. The Rakopi Formation comprises terrestrially deposited coal measures, while the North Cape Formation is generally composed of marine rocks. These Formations make up the Pakawau Group. The objective will be achieved using two key methods. Firstly, the derivation of TOC logs using Passey’s log overlay method (Passey et al., 1990) and secondly, the generation of source rock quality maps (i.e. source rock richness mapping and source potential index mapping). This will integrate concepts relating to petrophysical wireline logs, seismic interpretation, core log information, geochemical analysis, depth mapping and isopach mapping. The results obtained from this study confirms the petroleum potential of the organic rich intervals of the Taranaki Basin. Using Passey’s method it was shown that excellent average percent TOC values are encountered for both the Wainui Member of the North Cape Formation and the Rakopi Formation. From source potential index mapping, it can be concluded that the Rakopi formation has a high source potential index (>1000SPI) on the continental shelf, which indicates that it has excellent potential for petroleum generation. The Wainui Member however, shows less potential for petroleum generation on the shelf, this being attributed to generally low net thicknesses on the shelf.
55

The Evaluation of Subsurface Fluid Migration using Noble Gas Tracers and Numerical Modeling

Eymold, William Karl January 2020 (has links)
No description available.
56

Sedimentary record of tectonic growth along a convergent margin: Insights from detrital zircon geochronology of Mesozoic sedimentary basins and modern rivers in south-central Alaska

Cooper R Fasulo (8067611) 02 December 2019 (has links)
<p>This study presents new detrital zircon geochronologic data from Jurassic to Cretaceous sedimentary basins and modern rivers in south-central Alaska in order to examine the sedimentary record of magmatism and tectonics associated with the Mesozoic to Cenozoic growth of the southern Alaska convergent margin. Jurassic to Cretaceous strata of the Wrangell Mountains, Nutzotin, and Wellesly basins formed coeval with the Mesozoic accretion of the Wrangellia composite terrane (WCT) to the continental margin. New detrital zircon data from the Wrangell Mountains and Nutzotin basins demonstrate that these basins were derived primarily from sources associated with the WCT, with little to no derivation from continental margin sources. Detrital zircon ages from the Wrangell Mountains and Nutzotin basins are very similar, suggesting that these basins may have initially formed in a connected retroarc basin system. New detrital zircon data from the Wellesly basin show that the basin was source chiefly from continental margin sources. These ages show that the Wellesly basin is not related to the Nutzotin basin as previously suggested, and may be genetically related to the Kahiltna basin; this suggests that ~330-390 km of post-collisional strike-slip offset occurred along the Denali Fault. Comparing our new data with a regional detrital zircon database from similar-aged depocenters shows that there is a strong provenance and temporal link between outboard and inboard depocenters, with these depocenters being sourced from the same magmatic arcs from the late Jurassic to the late Cretaceous. Our findings from these comparisons are most consistent with a scenario where the WCT was accreted to the margin along an eastward-dipping subduction zone, in contrast to recent suggestions that the accretion was the result of westward-dipping subduction. New and previously published detrital zircon ages from the Tanana, Matanuska-Susitna, and Copper River watersheds in south-central Alaska document the major magmatic episodes that occurred along the southern Alaska convergent margin. These magmatic episodes display a periodicity that is similar to documented cyclic magmatic patterns in other regions along the Cordilleran margin, suggesting similar processes may be occurring margin-wide. The magmatic record of south-central Alaska can also be compared with the magmatic record of other regions in the northern Cordillera such as the Coast Plutonic Complex in British Columbia and the western Alaska Peninsula, which shows a spatial and temporal relationship of magmatism along the entire northern Cordilleran margin.</p>
57

Stratigraphy and sedimentary environments of the Late Permian Dicynodon Assemblage Zone (Karoo Supergroup, South Africa) and implications for basin development

Viglietti, Pia Alexa January 2016 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Doctor of Philosophy. June 2016. / The Dicynodon Assemblage Zone (DiAZ) spans the last three million years of the Late Permian (Lopingian) Beaufort Group (Karoo Supergroup). Fluvio-lacustrine conditions covered the entire Karoo Basin during this period, preserved as the rocks of the Balfour, Teekloof, and Normandien formations. However widely separated exposures and few dateable horizons make correlating between lithostratigraphic subdivisions difficult. Here a revised litho- and biostratigraphic framework is provided for the Upper Permian DiAZ. The Balfour Formation’s Barberskrans Member (BM) is renamed due to identifying the Oudeberg Member and not the BM at the current type locality (Barberskrans Cliffs). It is renamed Ripplemead member (RM) after Ripplemead farm 20 km north of Nieu Bethesda where it outcrops. The Teekloof Formation’s Javanerskop member and Musgrave Grit unit in the central Free State Province are regarded mappable units whereas the Boomplaas sandstone (BS) may represent a unit that is a lateral equivalent to the Oudeberg Member. Palaeontological and detrital zircon data suggest none of these locally persistent sandstone horizons correlate temporally. Three index fossils that currently define the DiAZ (Dicynodon lacerticeps, Theriognathus microps, and Procynosuchus delaharpeae) appear below its lower boundary and disappear below the Permo-Triassic Boundary (PTB), coincidentally with the appearance of Lystrosaurus maccaigi. The base of the DiAZ is redefined, with the revived Daptocephalus leoniceps and T. microps re-established as the index fossil for the newly proposed Daptocephalus Assemblage Zone (DaAZ), and is subdivided into two subzones. Da. leoniceps and T. microps’ appearance define the lower and L. maccaigi defines the base of the upper subzone. The same patterns of disappearance are observed at the same stratigraphic interval throughout the basin, despite the thinning of strata northward. Additionally wetter floodplain conditions prevailed in the Lower DaAZ than in the Upper DaAZ which likely reflects climatic changes associated with the Permo-Triassic mass extinction (PTME). Palaeocurrent and detrital zircon data demonstrate a southerly source area, and recycled orogen petrography indicates the Cape Supergroup is the source of Upper Permian strata. Dominant late Permian zircon population supports the foreland nature of the Karoo Basin. Orogenic loading/unloading events are identified by two fining-upward cycles, separated by a diachronous third-order subaerial unconformity at the base of the RM and Javanerskop members. Sediment progradation northwards was out-of-phase with the south and wedge-shaped. Distributive fluvial systems depositing sediment within a retroarc foreland basin best explains these observations. Lithostratigraphic beds and members are recommended for use as local marker horizons only in conjunction with other proxies, such as index fossils or radiometric dates in future studies. / LG2017
58

An Investigation of the First-Order Mechanics of Polygonal Fault Networks of Utopia Planitia, Mars

Islam, Fariha 01 January 2009 (has links) (PDF)
This study investigates the first-order mechanics of polygonal fault networks in Utopia Planitia, Mars and whether terrestrial sedimentary basin polygonal terrains are an analog for giant Martian polygons since there is an overlap in scale between the 3 km terrestrial polygons and the 1-40 km giant polygons of Mars. Volumetric contraction accommodates the extensional faulting observed in both cases. Boundary Element Method numerical models are used to simulate the first-order-mechanics of the faulting process. Models use material properties for wet, fine sediment, and apply an extensional strain to produce volumetric contraction. Fracture seeds that simulate the buried topography beneath the basin are placed at the base of the model. MOLA tracks from the Highlands are used to create the uneven topography beneath the basin since the underlying topography of the Northern Lowlands is thought to be similar to the topography of the older, Southern Highlands. The model investigates whether 1 & 2 km layer of wet, fine sediments will produce the fracture spacing observed within the polygonal terrains in Utopia (~5 – 6.5 km). A fracture network that is similar to the scale of the polygonal terrain in the Utopia Basin is established within the model at low strain, supporting the idea that buried topography could be the primary scaling factor for the polygon grabens. The results do not constrain an upper limit for strain; the observed trough widths in Utopia suggest that further strain was expressed by the widening of the troughs. Material properties for wet, fine sediments, analogous to the terrestrial counterpart, are appropriate for the model to match what is observed in Utopia. The power-law scale of Highlands topography controls the scale of the surface fracture spacing in the models. Measurements of running average of trough spacing along radial transects with respect to the center of the basin did not yield a monotonic decrease in trough spacing as would be expected for a smooth basement with no buried topography. Study results support the case for buried topography controlling the scale of the giant polygons of Utopia Planitia.
59

Multi-scale characterization of dissolution structures and porosity distribution in the upper part of the Biscayne aquifer using ground penetrating radar (GPR)

Unknown Date (has links)
The karst Biscayne aquifer is characterized by a heterogeneous spatial arrangement of porosity, making hydrogeological characterization difficult. In this dissertation, I investigate the use of ground penetrating radar (GPR), for understanding the spatial distribution of porosity variability in the Miami Limestone presented as a compilation of studies where scale of measurement is progressively increased to account for varying dimensions of dissolution features. In Chapter 2, GPR in zero offset acquisition mode is used to investigate the 2-D distribution of porosity and dielectric permittivity in a block of Miami Limestone at the laboratory scale (< 1.0 m). Petrophysical models based on fully saturated and unsaturated. water conditions are used to estimate porosity and solid dielectric permittivity of the limestone. Results show a good correspondence between analytical and GPR-based porosity estimates and show variability between 22.0-66.0 %. In Chapter 3, GPR in common offset and common midpoint acquisition mode are used to estimate bulk porosity of the unsaturated Miami Limestone at the field scale (10.0-100.0 m). Estimates of porosity are based on the assumption that the directly measured water table reflector is flat and that any deviation is attributed to changes in velocity due to porosity variability. Results show sharp changes in porosity ranging between 33.2-60.9 % attributed to dissolution areas. In Chapter 4, GPR in common offset mode is used to characterize porosity variability in the saturated Biscayne aquifer at 100-1000 m field scales. The presence of numerous diffraction hyperbolae are used to estimate electromagnetic wave velocity and asses both horizontal and vertical changes in porosity after application of a petrophysical model. Results show porosity variability between 23.0-41.0 % and confirm the presence of isolated areas that could serve as enhanced infiltration or recharge. This research allows for the identification and delineation areas of macroporosity areas at 0.01 m lateral resolution and shows variability of porosity at different scales, reaching 37.0 % within 1.3 m, associated with areas of enhanced dissolution. Such improved resolution of porosity estimates can benefit water management efforts and transport modelling and help to better understand small scale relationships between ground water and surface water interactions. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
60

Comparaison de la composition des roches métasédimentaires archéennes dans six bassins de la province du Supérieur : une étude géochimique et statistique /

Doyon, Julie, January 2004 (has links)
Mémoire (M.Sc.T.) -- Université du Québec à Chicoutimi, 2004. / Bibliogr.: f. [149]-154. Document électronique également accessible en format PDF. CaQCU

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