This diploma thesis deals with epoch GNSS measurement by static method at Tetčice polygon. The main purpose is to confirm the geological activity of the Earth's surface on the territory of the village, caused by a tectonic fault. As part of the thesis, the fourth phase of observation was carried out in June 2016 to detect horizontal shifts on four concrete pillars with depth stabilization and forced centering equipment. Results are velocity vector maps obtained by processing the measured data from all the measurement phases that have been performed so far. The thesis also contains the theoretical basis of geological conditions in the area and a description of technology of global navigation satellite systems.

Beitrag zu geodätischen Arbeiten im Gebiet des subglazialen Lake Vostok anläßlich einer Festschrift zum 65. Geburtstag von Prof. Reinhard Dietrich.

<div> <div> <div> <p>The combination of field-based studies and numerical modeling provides a robust tool for evaluating geologic and geodynamic processes along a convergent margin. Complex and persistent tectonic activity and a novel suite of geophysical observations make the southern Alaskan convergent margin a key region to evaluate these processes through both basin analysis studies and geodynamic modeling. This conceptual approach is utilized to explore the active driving forces of surface deformation throughout southcentral Alaska, as well as the geologic record of regional Cenozoic tectonic processes. </p> <p>New sedimentologic, chronostratigraphic, and provenance data from strata that crop out within the central Alaska Range document a previously unrecognized stage of Eocene – early Miocene strike-slip basin development along the northern side of the central Denali fault system. This stage was followed by Miocene-Pliocene deformation and exhumation of the central Alaska Range, and basin development and northward sediment transport into the Tanana foreland basin. This portion of the study provides insight into Cenozoic tectonics and basin development in the central Alaska Range. </p> <p>How transpressional tectonics are manifest in the modern-day, in combination with shallow subduction processes, are not well understood for the southern Alaskan convergent margin. Simulations of the 3-D deformation of this region allow for investigation of the complex relationship between these tectonic processes and surface deformation. Results from this study display the far-field affect that strong plate coupling along the shallowly subducting Yakutat slab has on the surface deformation of southcentral Alaska. Our models also show that partitioning of this convergence is observed along the Denali fault system. Additionally, our results indicate the subducting slab is segmented into separate Pacific, Yakutat and Wrangell slab segments. This variation in slab structure exerts control on the upper plate response to shallow subduction.</p> </div> </div> </div>

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / Microfiche copy available in Archives and Science. / Bibliography: leaves 273-291. / by Mai Yang. / Ph.D.

No description available.

No description available.

The ENE trending Brandberg West - Goantagab Sn-W belt is located in the Southern Kaoko Zone of the northern coastal branch of the Damara Orogen. The lithologies in this area are turbiditic and consist of three schist units separated by two marble horizons, all of which are correlated with the Swakop Group. The formations are intensely folded by at least three episodes of which the first two are coaxial and resulted in prominent, approximately N-S trending, structures. Sn and Sn-W mineralization predominantly occurs as vein and replacement type mineralization. Vein type mineralization occurs as Brandberg West, Frans Prospect, Gamigab Prospect and the Goantagab Mining Area. The vein type mineralization is accompanied by intense alteration, consisting of greisenization, sericitization, hematitization and carbonatization. Replacement-type, hematite-cassiterite mineralization, occurs in the Goantagab Mining area in the marble close to, or at the schist marble contact. Intense ferruginous alteration of the marbles in this area, is associated with veins, which terminate against, or cross cut the marble. A regional metal zonation, ranging from Sn-W mineralization with minor sulphides at Brandberg West to Sn-sulphide mineralization at Goantagab can be detected. This metal zonation is attributed to the distance of the mineral locality from the source area, with Goantagab representing a distal and Brandberg West a proximal position relative to the source area. Structural, mineralogical and geological features of the mineralization in this area suggest that processes of ore genesis may be related to anorogenic magmatism of Karoo age.

Thesis (PhD (Earth Sciences))--University of Stellenbosch, 2009. / Fluid-present partial melting has generally been regarded a poor candidate for effecting crustal differentiation. In this study I report on anatectic metasediments from the Pan-African Damara Belt in Namibia that have undergone fluid-present biotite melting at a relatively low temperature, yet appear to have lost a significant volume of melt. In situ anatectic features have been identified on the basis of the existence of new generations of cordierite and/or garnet produced as the solid products of incongruent anatexis within or adjacent to leucosomes, that most commonly occur as lens shaped pods at a high angle to the lineation and formed during extension in a direction parallel to the long axis of the orogeny. Within these sites biotite underwent incongruent melting via the reaction Bt + Qtz + Pl + H2O = Melt + Grt + Crd. Cordierite nucleated on preexisting crystals within the bounding gneiss; garnet nucleated within the fracture sites (leucosomes) and typically occurs as individual, large (50 to 120 mm in diameter) poikiloblastic crystals. Thermobarometry applied to the anatectic assemblage yields low-temperature, granulitefacies peak conditions of 750 °C, 0.5 GPa. This temperature is approximately 100 °C lower than the accepted conditions for the onset of fluid-absent biotite melting. This, coupled to the focussing of anatexis on extensional fractures, suggests that anatexis occurred through waterpresent biotite incongruent melting. In order to better understand this process, both fluid-absent and water present partial melting experiments were conducted within the temperature interval 700 to 900 °C at 0.7 GPa. In the fluid-absent experiments, biotite incongruent melting started between 800 and 850 °C to produce melt coexisting with peritectic garnet and cordierite. In contrast, in water-saturated experiments, biotite melted via the reaction Bt + Pl + Q + H2O = Grt + Crd + Melt, between 700 and 750 °C, to produce melt, cordierite and garnet in the proportions 73:24:3.

O paralelismo entre antigos cinturões colisionais e sistemas de riftes mais jovens é amplamente reconhecido e especialmente observado ao longo do Oceano Atlântico. A relação entre estruturas litosféricas herdadas e a nucleação de sistemas de riftes tem sido o foco de muitos estudos. Entretanto, a relação entre estruturas herdadas e estruturas neo-formadas (i.e. durante a extensão) e a estruturação de margens passivas conjugadas ainda é pouco entendida. Na presente tese, usamos uma versão muito eficiente do código computacional Lagrangiano- Euleriano de elementos finitos FANTOM para modelar fluxos termo-mecânicos acoplados visco-plásticos de forma a entender a geodinâmica do processo de rifteamento considerando os efeitos das estruturas tectônicas herdadas e da estrutura reológica na litosfera continental. Os modelos consideram quantias variadas de extensão e contração prévios para desenvolver a herança tectônico-estrutural, a qual é ou não reativada durante o desenvolvimento da margem passiva. Nossos resultados mostram que: 1) as primeiras reativações da cunha orogênica ocorrem seguindo zona de cisalhamento principal de escala litosférica (antiga sutura); 2) zonas de cisalhamento crustais (antigos cavalgamentos) são parcial ou totalmente reativadas dependendo da quantia de contração anterior; 3) com pouca contração anterior, os cavalgamentos thick-skin são eficientemente reativados e controlam a formação da margem passiva; 4) maiores quantias de contração prévia permitem que zonas de cisalhamento afastadas da sutura não dão reativadas e preservam a estrutura orogênica; 5) a reativação de zonas de cisalhamento compressivas dominam durante os estágios iniciais do rifteamento, enquanto que em estágios finais e de afinamento crustal, dominam estruturas neo-formadas. Nossos modelos ajudaram a explicar algumas características das margens passivas conjugadas do Espírito Santo - Kwanza no Atlântico Central Sul, e da margem passiva norueguesa no Mar do Norte. Nossos modelos também mostraram que diferenças reológicas entre a crosta superior e a crosta inferior causam um desacoplamento durante subducção e posterior educção. Este último processo, associado ao necking termal da astenosfera ascendente, é responsável por deixar lascas de crosta inferior no canal de subducção-educção no manto litosférico, como é evidenciado por antigas zonas de subdução fósseis associadas à margem conjugada Newfoundland-Iberia. Dessa forma, a remoção de crosta inferior em margens passivas conjugadas pode ocorrer muito antes do processo de rifteamento. / The parallelism between older collisional belts and younger rift systems is widely known and particularly portrayed along the Atlantic Ocean. In what follows, the relationship between lithospheric inherited structures and nucleation of rift systems has been focus of many studies. Nevertheless, it is still poorly understood how inherited tectonic and new-formed structures (i.e. during extension) affect the final architecture of rifted conjugate passive margins. In this thesis we use a modified highly efficient version of the Arbitrary Lagrangian-Eulerian finite- element code FANTOM to model thermal-mechanical coupled, plane-strain, viscous-plastic creeping flows to understand the geodynamics of the rifting process considering the effects of tectonic structural inheritance and rheology on the final architecture of rifted conjugate margins. The models consider different amounts of previous extension and contraction to produce the structural inheritance that is reactivated or not during rifting. Our results show that: 1) first reactivations occur along the lithospheric former suture zone; 2) upper crustal thick skinned basement thrusts are partially or fully reactivated depending on the amount of prior contraction and size of the orogen; 3) with a small amount of contraction, thick skinned thrusts are efficiently reactivated in extension and provide the template for rifted margin formation; 4) with larger amounts of precursor contraction, thick skinned thrusts distal to the lithospheric suture zone do not reactivate in extension; 5) reactivation of prior contractional shears dominates during the early stages of rifting, whereas during the final stage of rifted passive margin formation new-formed extensional shears dominate. Models with less precursor extension and more contraction resulted in a rifted conjugate passive margin similar to the Espírito Santo-Kwanza conjugate in the Central South Atlantic, whereas more precursor extension and less contraction, develops into margin showing similar behavior of fault reactivations in the Norwegian margin, North Atlantic. Our models also show that rheological differences between upper and lower continental crusts cause them to decouple both during subduction and subsequent eduction. The latter process, associated to thermal necking of the upwelling asthenosphere, is responsible to leave slivers of previously subducted lower continental crust within the eduction channel in the mantle lithosphere, as it is seismically evidenced under the Newfoundland-Iberia rifted conjugate margins. In what follows, lower continental crust of the former subducting plate can be removed long before depth-dependent extension during magma-poor rifted margin development.

O paralelismo entre antigos cinturões colisionais e sistemas de riftes mais jovens é amplamente reconhecido e especialmente observado ao longo do Oceano Atlântico. A relação entre estruturas litosféricas herdadas e a nucleação de sistemas de riftes tem sido o foco de muitos estudos. Entretanto, a relação entre estruturas herdadas e estruturas neo-formadas (i.e. durante a extensão) e a estruturação de margens passivas conjugadas ainda é pouco entendida. Na presente tese, usamos uma versão muito eficiente do código computacional Lagrangiano- Euleriano de elementos finitos FANTOM para modelar fluxos termo-mecânicos acoplados visco-plásticos de forma a entender a geodinâmica do processo de rifteamento considerando os efeitos das estruturas tectônicas herdadas e da estrutura reológica na litosfera continental. Os modelos consideram quantias variadas de extensão e contração prévios para desenvolver a herança tectônico-estrutural, a qual é ou não reativada durante o desenvolvimento da margem passiva. Nossos resultados mostram que: 1) as primeiras reativações da cunha orogênica ocorrem seguindo zona de cisalhamento principal de escala litosférica (antiga sutura); 2) zonas de cisalhamento crustais (antigos cavalgamentos) são parcial ou totalmente reativadas dependendo da quantia de contração anterior; 3) com pouca contração anterior, os cavalgamentos thick-skin são eficientemente reativados e controlam a formação da margem passiva; 4) maiores quantias de contração prévia permitem que zonas de cisalhamento afastadas da sutura não dão reativadas e preservam a estrutura orogênica; 5) a reativação de zonas de cisalhamento compressivas dominam durante os estágios iniciais do rifteamento, enquanto que em estágios finais e de afinamento crustal, dominam estruturas neo-formadas. Nossos modelos ajudaram a explicar algumas características das margens passivas conjugadas do Espírito Santo - Kwanza no Atlântico Central Sul, e da margem passiva norueguesa no Mar do Norte. Nossos modelos também mostraram que diferenças reológicas entre a crosta superior e a crosta inferior causam um desacoplamento durante subducção e posterior educção. Este último processo, associado ao necking termal da astenosfera ascendente, é responsável por deixar lascas de crosta inferior no canal de subducção-educção no manto litosférico, como é evidenciado por antigas zonas de subdução fósseis associadas à margem conjugada Newfoundland-Iberia. Dessa forma, a remoção de crosta inferior em margens passivas conjugadas pode ocorrer muito antes do processo de rifteamento. / The parallelism between older collisional belts and younger rift systems is widely known and particularly portrayed along the Atlantic Ocean. In what follows, the relationship between lithospheric inherited structures and nucleation of rift systems has been focus of many studies. Nevertheless, it is still poorly understood how inherited tectonic and new-formed structures (i.e. during extension) affect the final architecture of rifted conjugate passive margins. In this thesis we use a modified highly efficient version of the Arbitrary Lagrangian-Eulerian finite- element code FANTOM to model thermal-mechanical coupled, plane-strain, viscous-plastic creeping flows to understand the geodynamics of the rifting process considering the effects of tectonic structural inheritance and rheology on the final architecture of rifted conjugate margins. The models consider different amounts of previous extension and contraction to produce the structural inheritance that is reactivated or not during rifting. Our results show that: 1) first reactivations occur along the lithospheric former suture zone; 2) upper crustal thick skinned basement thrusts are partially or fully reactivated depending on the amount of prior contraction and size of the orogen; 3) with a small amount of contraction, thick skinned thrusts are efficiently reactivated in extension and provide the template for rifted margin formation; 4) with larger amounts of precursor contraction, thick skinned thrusts distal to the lithospheric suture zone do not reactivate in extension; 5) reactivation of prior contractional shears dominates during the early stages of rifting, whereas during the final stage of rifted passive margin formation new-formed extensional shears dominate. Models with less precursor extension and more contraction resulted in a rifted conjugate passive margin similar to the Espírito Santo-Kwanza conjugate in the Central South Atlantic, whereas more precursor extension and less contraction, develops into margin showing similar behavior of fault reactivations in the Norwegian margin, North Atlantic. Our models also show that rheological differences between upper and lower continental crusts cause them to decouple both during subduction and subsequent eduction. The latter process, associated to thermal necking of the upwelling asthenosphere, is responsible to leave slivers of previously subducted lower continental crust within the eduction channel in the mantle lithosphere, as it is seismically evidenced under the Newfoundland-Iberia rifted conjugate margins. In what follows, lower continental crust of the former subducting plate can be removed long before depth-dependent extension during magma-poor rifted margin development.