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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

Spatial dynamics of the population in the Czech Republic (1989 - 2007)

Vobecka, Jana 30 August 2010 (has links) (PDF)
The aim of the thesis is to describe, analyse and discuss the development of spatial population dynamics in the Czech Republic between 1989 and 2007. Demographic structure and migration, the two components of spatial population dynamics, are analysed using two spatial dimensions, the urban-suburban-rural gradient and the core-periphery region distinction, using quantitative analyses, including gravity regression modelling of migration. The analysis primarily focuses on domestic migration as the main vehicle of spatial population dynamics. It discusses the structure, determinants, and temporal evolution of migration and its consequences on the population structure in different spatial categories. The thesis indicates that suburbanisation has recently become the main factor influencing Czech spatial population dynamics. The key factor determining migration destination is the social status of migrants, whereas age has only secondary importance. However, since Czechs are not very mobile, population dispersal is less large-scale than in Western-Europe. This explains why recent domestic migration patterns have had only a small measurable influence on the social or demographic structures of the population across spatial categories.
2

Crustal structure, gravity anomalies and subsidence history of the Parnaíba cratonic basin, Northeast Brazil

Tozer, Brook January 2017 (has links)
Cratonic basins cover more than 10% of Earth's continental surface area, yet their origin remains enigmatic. In this thesis a suite of new and legacy geophysical and geological data are integrated to constrain the origin of the Parnaíba basin, a cratonic basin in Northeast Brazil. These data include a 1400 km long, deep (20 s two-way travel time) seismic reflection profile, five +/- 110 km offset wide-angle split-spread receiver gathers, gravity anomaly, and well data. In the centre of the basin, the depth to pre-Paleozoic basement is ~ 3.3 km, a zone of midcrustal reflectivity (MCR) can be traced laterally for ~ 250 km at depths between 17-25 km and Moho depth is ~ 42 +/- 2 km. Gravity and P-wave modelling suggests that the MCR represents the upper surface of a high density (2985 kg m<sup>3</sup>) and V<sub>p</sub> (6.7 - 7.0 km s<sup>-1</sup>) lower crustal body, likely of magmatic origin. Backstripping of well data shows a concave up decreasing tectonic subsidence, similar in form to that commonly observed in rift-type basins. It is shown, however, that the seismic and gravity data are inconsistent with an extensional origin. It is shown that an intrusive body in the lower crust that has loaded and flexed the surface of the crust, combined with sediment loading, provides a satisfactory fit to the observed gravity anomaly, sediment thickness and basin shape. A buried load model is also consistent with seismic data, which suggest that the Moho is as deep or deeper beneath the basin centre than its flanks and accounts for at least part of the tectonic subsidence through a viscoelastic stress relaxation that occurs in the lithosphere following load emplacement. Comparative analysis of the Michigan and Congo basins shows gravity data from these basins is also consistent with a lower crustal mass excess, while subsidence analysis shows viscoelastic stress relaxation may also contribute to their early subsidence histories. However, unlike Parnaíba, both of these basins appear to have been subjected to secondary tectonic processes that obscure the primary 'cratonic basin' subsidence signals. Parnaíba basin, therefore, offers an excellent record for the investigation of cratonic basin formation.
3

Spatial dynamics of the population in the Czech Republic (1989 - 2007) / Dynamiques spatiales de la population en République tchèque (1989-2007)

Vobecká, Jana 30 August 2010 (has links)
L'objectif central de la thèse est de décrire, analyser et discuter la dynamique spatiale de la population tchèque entre 1989 et 2007. La structure démographique et les migrations, les deux composantes de cette dynamique spatiale, sont analysées par le biais de deux articulations de l’espace : le gradient urbain-périurbain-rural et la distinction régionale centre-périphérie. Des outils quantitatifs sont utilisés, avec en particulier un modèle gravitaire explicatif des migrations. L’orientation principale de l´analyse repose sur les migrations internes, comme étant l’agent majeur de la dynamique spatiale de la population. La structure, les déterminants, et l’évolution dans le temps de ces migrations sont étudiés, ainsi que leurs conséquences sur la structure démographique des ensembles spatiaux. La thèse indique que le processus de périurbanisation est récemment devenu un facteur majeur, influençant la dynamique spatiale de la population tchèque. Il est également établit que le facteur explicatif clé de la destination des migrations est le statut social du migrant, tandis que son âge ne présente qu’une importance secondaire. Cependant, étant donné que les Tchèques sont généralement peu mobiles, la déconcentration de la population s’opère à une échelle plus modeste que dans les pays d’Europe de l´Ouest. Cette constatation permet d’expliquer en quoi les tendances récentes des migrations résidentielles ont un impact mesuré relativement faible sur les structures sociales et démographiques de la population dans les catégories d´espace. / The aim of the thesis is to describe, analyse and discuss the development of spatial population dynamics in the Czech Republic between 1989 and 2007. Demographic structure and migration, the two components of spatial population dynamics, are analysed using two spatial dimensions, the urban-suburban-rural gradient and the core-periphery region distinction, using quantitative analyses, including gravity regression modelling of migration. The analysis primarily focuses on domestic migration as the main vehicle of spatial population dynamics. It discusses the structure, determinants, and temporal evolution of migration and its consequences on the population structure in different spatial categories. The thesis indicates that suburbanisation has recently become the main factor influencing Czech spatial population dynamics. The key factor determining migration destination is the social status of migrants, whereas age has only secondary importance. However, since Czechs are not very mobile, population dispersal is less large-scale than in Western-Europe. This explains why recent domestic migration patterns have had only a small measurable influence on the social or demographic structures of the population across spatial categories. / Cílem této disertační práce je popsat, analyzovat a diskutovat vývoj prostorové dynamiky obyvatel v České republice mezi lety 1989 a 2007. Demografická struktura a migrace, dvě komponenty prostorové dynamiky obyvatel, jsou analyzovány ve dvou prostorových dimenzích, v gradientu město-suburbium-venkov a v regionálním rozlišení jádrových a periferních regionů, prostřednictvím kvantitativní analýzy, včetně gravitačního regresního modelu migrace. Analýza se zaměřuje především na vnitřní migraci jako hlavního hybatele prostorové dynamiky obyvatel. Zabývá se strukturou, determinanty migrace a jejím vývojem v čase a také jejími dopady na strukturu obyvatel v jednotlivých prostorových kategoriích. V disertaci je ukázáno, že suburbanizace se v poslední době stala nejdůležitějším faktorem ovlivňujícím prostorovou dynamiku obyvatel v České republice. Hlavním faktorem určujícím směr migrace je sociální status migrantů, zatímco jejich věk má pouze druhořadý význam. Nicméně, tím, že Češi nejsou příliš migračně aktivní, populační dekoncentrace dosahuje menších rozměrů a objemů než v západoevropských zemích. To vysvětluje, proč novodobé migrační trendy měly zatím jen malý měřitelný dopad na sociální a demografické struktury obyvatel jednotlivých prostorových kategorií.
4

The Neoproterozoic tectonic evolution of the western Jiagenen Orogenic Belt and its Early Paleozoic-Mesozoic tectonic reworking / Evolution tectonique Néoproterozoïque de la chaîne de Jiangnan Occidental et sa réactivation au Paléozoïque inférieur Mésozoïque

Yan, Chaolei 29 October 2018 (has links)
La chaîne de collision d'âge néoprotérozoïque de Jiangnan, orientée NE-SW, marque la limite entre les blocs duYangtze et de Cathaysia. Son évolution tectonique reste encore débattue. Une des questions les plus controversées est l'âge de la collision entre les deux blocs. Afin d'acquérir une meilleure compréhension de ce problème, nous avons collecté des échantillons dans les couches sédimentaires situées au-dessus et au-dessous de la discordance dans le but de comparer les spectres d'âge des zircons détritiques et aussi de les confronter à ceux décrits dans les séries néoprotérozoïques des régions du Yangtze, Jiangnan et Cathaysia. En outre, nous nous sommes intéressés aux plutons granitiques d'âge néoproterozoïque de Sanfang et Yuanbaoshan, de type-S, situés dans la partie occidentale de la chaîne de Jiangnan afin de tracer l'évolution tectonique de la région depuis 830 Ma par la mise en œuvre de méthodes pluridisciplinaires : géologie structurale, géochronologie U-Pb, AMS, modélisation gravimétrique et thermochronologie Argon.Notre étude montre les résultats suivants : (i) La chaîne de Jiangnan s'est formée par la collision des blocs de Yangtze et Cathaysia entre ca. 865 and 830 Ma ; (ii) Les intrusions granitiques de 830 Ma se sont mises en place dans des formations encaissantes du groupe Sibao plissées et faillées. Les plutons ont été construits par accumulation latérale E-W de filons N-S, avec un écoulement horizontal du magma du sud vers le nord ; (iii). Un cisaillement ductile du haut vers l'Ouest a été reconnu dans la partie supérieure des plutons. Des âges Ar/Ar vers 420 Ma obtenus sur plusieurs grains de muscovite et biotite déformés impliquent que le cisaillement ductile peut être : a) formé pendant l'orogenèse du Paléozoïque inférieur de Chine du Sud, ou b) pendant la mise en place des plutons au Néoprotérozoïque dans une croûte chaude, sous la température de fermeture du chronomètre argon, puis lors de l'orogenèse du Paléozoïque inférieur, ce domaine crustal de Chine du Sud est passé au-dessous de 350°C; (iv) Durant la période 420-240 Ma, la région de Sanfang-Yuanbaoshana connu un refroidissement lent qui pourrait correspondre au ré-équilibrage isostatique de la croûte. / The Jiangnan Orogenic Belt is a NE-SW trending Neoproterozoic collisional suture, marking the boundary between the Yangtze Block and the Cathaysia Block. Its tectonic evolution is still debated. One of the most controversial questions is the timing of the collision between the Yangtze and Cathaysia blocks. In order to have a better understanding of this problem, we have collected the sedimentary rocks from the strata both overlying and underlying the Neoproterozoic unconformities to compare the detrital zircon age spectra between them, as well as to compare the detrital zircon spectra of Neoproterozoic sequences among the Yangtze, Jiangnan and Cathaysia regions. Moreover, we paid attention to the Neoproterozoic S-type granite plutons located in the western Jiangnan region in order to trace the crustal evolution in the Sanfang-Yuanbaoshan area since 830 Ma by multidisciplinary methods, including structural geology, geochronology, AMS, gravity modelling and Argon isotopic dating.Our study shows that : (i) The Jiangnan Orogenic Belt was built up due to the assembly of the Yangtze and Cathaysia blocks between ca. 865 and 830 Ma ; (ii) The 830 Ma granitic magma intruded into the pre-existing folds and faults in the Sibao group, the tongue-and/orsill-shaped plutonswere constructed by anE-W lateral accumulation of N-S oriented dykeswith adominantly northward horizontal magma flow from south to north ; (iii)A top-to-the-W ductile shearband has been identified on the top of plutons, (iv) the coherent mica Ar-Ar age of ca. 420 Ma, obtained from the deformed muscovite, implies that this shearing may be formed either a)during the Early Paleozoicorogeny, or b) during the Neoproterozoic plutons emplacement, then the plutons were exhumed by the Paleozoic orogeny ; (iv) During the 420-240 Ma period, the Sanfang-Yuanbaoshan area has experienced a slow cool ingrate, which may correspond to the isostatic re-equilibration of the crust.
5

Vznik kompoziční a texturní zonálnosti mělce uložených granitoidních těles / The Origin of Compositional and Textural Zoning of Shallow-Level Granitoid Plutons

Trubač, Jakub January 2015 (has links)
The principal goal of this Ph.D. Thesis is to contribute to the research on formation of compo- sitional and textural zoning in shallow-level plutons. Processes responsible for emplacement of individual plutons/pulses and the origin of compositional zoning in are addressed in a great detail, from the pluton-scale down to the micro-scale. The main emphasis in the more focused part of this text is on a combination of various quanti- tative data sets from two well-selected plutons (the Říčany Pluton in the Central Bohemian Plu- tonic Complex and the Melechov Pluton in the Moldanubian Batholith). These detailed studies are supported by further research on the Štěnovice, Čistá and Ševětín plutons. In this way we cover the evolution of Variscan magmatism in the heart of Bohemian Massif in its entirety, from Late Devonian till Permian. The thesis is based on combining field and structural studies (including the anisotropy of mag- netic susceptibility, AMS), textural analysis, petrological, geochronological and geochemical methods with geophysical investigations. Mathematical approaches have been designed and applied to the interpretation of geochemical data, with potential applications to other igneous systems. I strongly believe that only such comprehensive studies on well-selected case examples have a...

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