The main objective of diploma thesis is to evaluate the impact of the geological structure on the hydrogeological conditions in the northeastern part of Stráž block. The study area in northern Bohemia is characterised by Cenomanian and Turonian sandstone aquifers, which are horizontally divided by Lower Turonian aquitard. The thesis focuses groundwater level analysis and study hydrogeological impacts of faults, neovolcanic veins and disturbances of rock environment caused by uranium mining. First part of the study presents description of general geological and hydrogeological conditions in the area with summary of previous investigations and reports. Various hydraulic interventions during mining, which have great impact on the groundwater level situation are described. Based on the data from collected boreholes, contour maps of groundwater level are prepared to study its shape and temporal changes. Hydraulic communication through aquitard and through Stráž fault zone have been examined by correlations of groundwater levels. The results of the study confirm sealing effect of Stráž fault zone in the examined section. Barrier effect of the neovolcanic veins has been confirmed on several locations and examples of increased hydraulic conductivity as the result of fault disturbances have been located....

Mineralogical and petrographic analyses of the upper Jurassic - lower Cretaceous units in the vicinity of the Dinosaur National Monument quarry near Jensen, Utah, have elucidated their characteristics and the locations of formational boundaries. The lower part of the Morrison Formation is distinguished by a decreased amount of illite and an increased amount of kaolinite. In contrast, the underlying Curtis Formation contains an approximately equal mixture of illite and kaolinite. The lower Salt Wash Member and the upper Brushy Basin Member of the Morrison are both lithologically and mineralogically identifiable in this area. Above the boundary between the two, kaolinite decreases and illite increases. The strata above the Morrison, here recognized as an extension of the Cedar Mountain Formation, reveal another change in clay content. They contain kaolinite as the dominant clay mineral, whereas illite is almost completely absent. The upper Curtis Formation is a near-shore marine deposit, whereas the members of the Morrison Formation are fluvial and lacustrine. A possible climatic or depositional change is equated with the changes in the clay content within the members of the Morrison Formation. After deposition of the Morrison, the lower Cretaceous sediments that now comprise the Cedar Mountain Formation accumulated. These formed in a transitional zone (fluvial to littoral) and were eventually covered by the Dakota Formation (littoral) and the Mowry Formation (marine).

The modern plate tectonic paradigm provides a predictive model to understand what mediates dynamic processes at both plate margins and intraplate settings. At some locations on the Earth, the geological record provides evidence of apparent violations of this theoretical framework. In this dissertation, I examine a region on the rifted continental margin of Eastern North America, where at least four distinct episodes of magmatism occurred (in the Late Triassic, Early Jurassic, Early Cretaceous) since the onset of rifting and ultimate breakup of the supercontinent Pangea. It also coincides with a present-day low seismic velocity anomaly in the upper mantle. No other region on the Eastern North American Margin has a record of such anomalous dynamic processes occurring and persisting for more than 200 Myr. In this dissertation, I primarily use zircon U-Pb geochronology to establish the basic chronological framework in which magmatic and magmatic-hydrothermal systems in this region existed and persisted, establishing the temporal parameter space in which it will be possible to test geodynamic mechanisms for their formation. In Chapter 2, I use ultra-high precision zircon U-Pb geochronology via Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) to test whether the onset of magmatism in the largest igneous body in this region (the White Mountain Batholith) is linked to the eruption of the vast flood basalts within the Central Atlantic Magmatic Province (CAMP) and whether its apparent duration is indeed > 50 Myr, as previous workers using whole rock K-Ar and mineral Ar-Ar geochronologic methods suggest. My work uncovered a previously unknown episode of rift-related magmatism in the region that precedes the both the CAMP and the emplacement of the White Mountain Batholith by 3 – 5 Myr. In Chapter 3, I use a combination of high-precision zircon U-Pb geochronology and absolute plate motion models to test whether the Cretaceous igneous province in this region resulted from hot spot magmatism as North America moved over the purported Great Meteor Hotspot. These results cannot falsify the hotspot hypothesis and the new zircon U-Pb ages therefore provide the best available chronological constraints for one of the longest-lived hot spot tracks on the Earth. In Chapter 4, motivated by the confirmation of age discrepancies between low- and intermediate-temperature chronometers and the zircon U-Pb ages presented in Chapter 2, I use a combination of both CA-ID-TIMS and LA-ICP-MS zircon U-Pb geochronologic techniques to place constraints on the timing and duration of magmatism for the Late Triassic-Early Jurassic province. The results of this chapter demonstrate that the magmatism of the White Mountain Magma Series occurs in discrete pulses through much of the Jurassic. Together with zircon Hf isotopic analyses from select samples, I synthesize these age results and construct a hypothesis testing framework in which it will be possible for future investigators to unravel the geodynamic complexities in this region. I provide recommendations for future work and emphasize the need for unified approaches coupling geochronology, geochemistry, and geophysics, to test the range of possible mechanisms responsible for these episodes of anomalous tectono-magmatic activity.

Global warming and its influence on the environment has become a popular and widespread issue. Nowadays, an analogy of a high latitude ecosystem during the greenhouse type of climate does not exist. The Cretaceous polar ecosystem gave us a unique possibility of understanding these extreme ecosystems and the specific adaptations of organisms to these conditions. Such types of ecosystem are crucial for a better understanding of possible future climate changes. This thesis focusses on the adaptation strategies of land plants during the Late Cretaceous in the Arctic peninsula. The land plants responded to these specific solar conditionals in two different ways: evergreen or deciduous. The fossil material for this study comes from Brandy Bay and Crame Col, James Ross Island, Antarctic. The material was collected in a continuous sequence from Kotic point to Santa Marta Formation (Cenomanian - Companian). A detailed and systematic analysis was performed on five out of fifty-five samples that well represented the studied region and age: Agathoxylon kellerense, Agathoxylon antarcticus, Araucarioxylon chapmanae, Podocarpoxylon multiparenchymatosum and Phoroxylon sp. Based on the detailed study of Agathoxylon kellerense (sample number AN34) wood anatomy and growth rings structure, adaptation strategies were...

In this thesis, the results of microfossil, biofacies, and geochemical analyses (µXRF) of the Upper Cretaceous (Turonian) Ferron – Notom delta, Utah, USA are reported and discussed. The Notom delta is the oldest of three clastic deltas in the Ferron Sandstone Member, Mancos Shale Formation. Foraminifera and testate amoebae were recovered from ninety-eight mudstone samples among five well-exposed outcrops (Caineville North, Steamboat, Blue Hills, Neilson Wash, and Coalmine Wash). Detailed observations showed foraminifera, and testate amoebae tests have undergone post-burial compression (flattening), dissolution, and transport/reworking; therefore, identification of these assemblages to their species level is difficult. The micropaleontological analysis of the Ferron-Notom delta consists of three studies. Morphogroup analysis was applied on foraminifera and testate amoebae, where a relationship between the test morphology and habitat was established. Morphogroup analysis resulted in four main morphogroups and eleven morphotypes and were assigned to life mode, environment, and feeding strategies. Three foraminifera morphogroups and one testate amoebae morphogroup were established indicate a range of environments, from shallow shelf to shallow shelf to lagoon/estuary environments. Biofacies analysis using the morphotypes was applied on three outcrops (Caineville North, Steamboat, and Blue Hills). We use the morphotypes to define the four main biofacies using cluster analysis, and biodiversity indices. Four biofacies showed marine and fluvial (freshwater) influences. Salinity and OM indices were derived from the relationship of foraminifera morphotypes (BiS, TrS, TS) and testate amoebae morphotypes (Ta-F, Ta-D, Ta-S) that follows lithofacies trends. Because of the under-representation of calcareous foraminifera (due to taphonomic and/or diagenetic factors), the biodiversity indices are treated herein as relative measures. Despite this taphonomic bias, the agglutinated foraminifera and testate amoebae morphogroups show trends with salinity both among the outcrops and stratigraphically within the outcrops. The Blue Hills outcrop represents the most landward and lowest salinity environment (tidally-influenced backwater), Steamboat is more coast proximal with a higher salinity of the delta front and fluvial estuarine environments, and the Caineville North outcrop represents the most coast proximal (fluvial/estuarine to deltaic/prodeltaic) with salinities ranging from low to medium. It appears that the landward transport and coastward of tests was a significant source of taphonomic bias. Nonetheless, the assemblages provide useful depositional information that correlates with previously documented lithofacies data. A salinity index based on a ratio of trochospiral taxa versus testate amoebae was found to provide a useful measure of coastal proximity that matches lithofacies trends. The µXRF analysis was conducted on twenty-nine mudstone samples from the Caineville North outcrop to examine elemental proxies for paleo-salinity (Sr/Ba), organic matter (K/S), redox (V/Ni), and sediment sources (Zr/Rb, Ti/Fe, Ti/Ca). Twenty-nine surface mudstone samples collected from four lithofacies representing prodelta, delta front, fluvial valley fill and shelf environments. Fourteen elements (Ti, Fe, Ca, Sr, Ba, Ni, Rb, Zr, S, V, Cu, Mn, Si, and K) were used to calculate proxy ratios to detect variations in terrigenous sediments, carbonate production, salinity, grain size, and fluvial inputs in the Caineville North outcrop. Elemental data showed good correspondence between the elemental data and the lithofacies and microfossil indices. Sr/Ba and Ca/Fe showed relationships with carbonate content and proximity to the shoreline. The paleo-salinity proxy (Sr/Ba) did not respond to salinity, but was more responsive to lithological change of carbonate content. The microfossil salinity index seems to be a more accurate paleo-salinity indicator. The proxy for fluvial input of sediment (Zr/Rb and Ti/Fe) agree well with the lithofacies trends, and Zr/Rb and Ti/Fe showed highest values within the fluvial valley fill facies, with higher variability of Ti/Fe compared to the other lithofacies (prodelta, delta front, and shelf), corresponding to response to the proximity of the depositional sites to a fluvial sediment source. The redox proxy V/Ni matched the previously derived microfossil OM index ("bolivind-type" taxa) showing a strong relationship between eutrophication and redox trends. The study aims to establish important baseline geochemical compositions of sediment sources to establish patterns and trends with sediment succession in the deeper basin (offshore; i.e. Mancos Shale). Potentially, these nearshore to fluvial trends will provide important geochemical data to assess changes in paleoclimate, and sea-level in offshore sediment successions. / Dissertation / Doctor of Philosophy (PhD)

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Diagenetic and structural aspects of tight gas sandstones must be addressed concurrently in order to fully understand low-permeability sandstones and to better predict their reservoir quality attributes that arise from a combination of pore-scale and fracture distribution characteristics. This dissertation focuses on aspects of rock evolution that are germane to concurrent structural and diagenetic evolution, such as loading and thermal history, rock mechanical property evolution, and fracture timing. I tested the hypothesis that the cement precipitation step, governed by thermal exposure and grain surface attributes, governs how sandstone attributes evolve using observations from the Late Cretaceous Williams Fork sandstones from the Piceance Basin, Colorado. My research shows that essential information for predicting and understanding fracture patterns in sandstone can be obtained by unraveling cement precipitation (diagenetic) history. Fractures depend on the mechanical properties existing during fracture growth. I show that key rock mechanical properties (subcritical crack index, Young's modulus and Poisson's ratio), petrophysical behavior, and reservoir quality depend in a systematic way on time-temperature history and the intrinsic grain surface attributes of these sandstones. I classified the Williams Fork lithofacies petrographically and correlated those with log responses to create a model that can be used to predict reservoir quality and diagenesis directly from well logs. I determined rock mechanical characteristics by measuring the subcritical crack index (SCI), a mechanical property that influences fracture distribution characteristics, and by examining log-derived bulk mechanical properties. To quantify the influence of quartz cementation on the SCI and to determine the range of SCI values for sandstone of given framework composition at different diagenetic stages, I measured SCI on Williams Fork core samples and their outcrop equivalents. Diagenetic modeling is applied to determine the sandstone characteristics during fracturing. / text

Large depression cone in water table was formed due to mining in surroundings of Střeleč quarry. The concentrated inflow from conduits to quarry is up to 70 l/s. Large conduit systems are created by flowing water into the quarry. The biggest conduit system was at least 300 m long and 17 m high with maximum calculated volume of 22 thousands m3 . Evolution of these conduits usually takes several months to few years. Fast conduit evolution allows to study erosion processes in detail in situ. In the thesis I am describing conduits, character of flow and erosion processes. Measured flow velocities in conduits are up to 0,4 m/s with hydraulic gradient 1 to 5%. Flow velocities and hydraulic gradients are typical for piping erosion. Piping initially forms small protoconduits. The bigger conduits are formed as water is progressively drained from larger area. Conduits are following fracture surfaces, which are also limiting the conduit propagation to the sides. Above water table the conduits are enlarged mainly by mass wasting of undercut sandstone slabs. For distinguishing less and more erodible parts of sandstone, we adapted and partially developed a method for measuring erodability (REI) and drilling resistance (DR). Both are used to compare different types of sandstone surfaces. In lowermost part of the...

The post-Triassic Nautiloidea are not as popular theme within fossils cephalopods research as for example ammonites. They are not very abundant in the fossil records except some rare localities and areas, their morphology is quite conservative and due to the usually poor preservation, their determination and assigning to the species even to genera level is often complicated. Exceptional are taxa with very specific morphology and short stratigraphic and endemic occurrence, which are even suitable for biostratigraphic interpretations. Problematic is also the often poor taxonomical representation of the type material and revision of many taxa is needed. Still nautilids are often represented by reasonable amount in the paleontological collections of natural history museums due to the long history of fossils collecting. Also the scientific literature has been dedicating at least some space to this group since 19 century. The aim of this study is to create an overview about the post- Triassic, especially Upper Cretaceous nautiolidea in the European region of epicontinental seas and prepare a good basement for extensive study of this group. Due to this aim the study is primarily focused on determination of morphological features and also problematic with their interpretation according to the variable...