|
|
Trace elements in carbonates of the Czech Creataceous Basin
Štěpánková, Anna ; Procházka, Václav (advisor) ; Štaffen, Zdeněk (referee)
The presented work is focused on research of distribution of trace elements in carbonate sediments and fossils in the Bohemian Cretaceous Basin. To obtain maximum information about the composition of the primary carbonate and its crystallization environment, the trace elements were analyzed mainly in fractions soluble in diluted acid. Another objective is the comparison of trace-element abundance in the soluble fraction and in the residue (or in the total mass of the samples). The results show that there are no systematic differences in the chemical composition of the original carbonate between various regions and stratigraphic positions (Cenomanian - upper Turonian). Elements like Sr, Mg and Mn in carbonate were affected by diagenesis, but contents and mutual ratios of the rare earth elements in all carbonates are similar and are characterized by negative cerium anomaly. The Ce-anomaly could be attenuated by elevated content of clastic matter, and in the soluble portions ocassionally via contamination by secondary phosphate. On the other hand, soluble fractions of limonite-rich and calcite-poor sandstones have positive cerium anomaly, which is the effect of Ce-sorbtion on limonite.
|
|
|
Oyster bioherms in the Bohemian Cretaceous Basin
Rantuch, Jakub ; Košťák, Martin (advisor) ; Frank, Jiří (referee)
Frustration from shape and size variability of oyster's species Rhynchostreon suborbiculatum (Lamarck) is long known phenomenon. In current state of his systematic it is not possible to consider it fully satisfying. Is it is shown in study of genus Gryphaea by Jones and Gould (1999), that application of modern analytical methods, undoubtly lightens long-darkned places of evolution process. Idea of Videt and Neraudeau (2003), that shape variability of Rhynchostreon suborbiculatum (Lamarck) probably also mirrors heterochronic processes, introduces inspirative and good foundation for future research in this field. Occurence of this oyster is proved from huge range of sites in Bohemian Cretaceous Basin area. It is combination of rich occurance, unique preservation and variability of lithological settings, which gives us unique starting point for next step to solve significant problem. Based on population analyses consisting of biometrical studies supported by oxygen isotope analyses, in future, it will be possible to reach sufficient conclusions of this issue, and progress in our knowledge.
|
|
|
Planktonic ecosystems of the Upper Jurassic and Cretaceous (calcareous nannoplankton, calpionellids)
Svobodová, Andrea ; Holcová, Katarína (advisor) ; Skupien, Petr (referee) ; Oszczypko-Ciowes, Marta (referee)
The presented PhD thesis is compiled as a commentary to four published papers, which deal with planktonic assamblages of the Upper Jurassic and Cretaceous, namely with calcareous nannofossils and calpionellids. The first part of the dissertation thesis describes the main characteristics of the studied fossil groups with focus on their morphology, palaeoecology, evolution and systematics. The chapter of calcareous nannoplankton gives special attention to the biostratigraphicaly important genus Nannoconus Kampter 1931. Next chapters describe the methods of the laboratory processing of the sediments and the geological settings of the studied areas. The thesis is focused on two areas. At first the selected localities in the Bohemian Cretaceous Basin, i.e. Upper Turonian and Upper Coniacian, are described. Generally, the Upper Cretaceous platform sediments of the middle European basins are rich in calcareous nannoplankton. These fossils represent important marker for biostratigraphical and palaeoecological interpretations. The second part describes carbonate rocks of the Upper Jurassic and Lower Cretaceous of the Tethyan area. In this case, calcareous nannoplankton and calpionellids are an essential part of the modern multidisciplinary form of the Jurassic- Cretaceous (J/K) boundary interval research....
|
|
| |
|
|
Channels eroded by groundwater flow in Strelec quarry: erosion processes and factors influencing channel evolution
Soukup, Jan ; Bruthans, Jiří (advisor) ; Grmela, Arnošt (referee)
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...
|
|
|
Depositional architectures, stratigraphy, and depositional regime of Lower-Middle Turonian sandstone bodies, northwestern part of the Bohemian Cretaceous Basin
Skopcová, Monika ; Uličný, David (advisor) ; Čech, Stanislav (referee)
Sandstone bodies of the Lower and Middle Turonian well exposed in the northwestern part of the Bohemian Cretaceous Basin represent deposits of the coarse-grained deltas. Aim of this paper is to interpret the architectures, stratigraphy and depositional regime of these bodies. The main architectural elements are clinoforms which show intermediate dip 4ř to 5ř of the delta slope and the direction of the progradation of the delta to the west-southwest. Correlation of the lithological profiles with the well - log data provided the stratigraphic classification of the outcrops in the studied area mostly to the genetic sequence TUR2. Correlations in one of the two stratigraphic cross - sections revealed the existence of the second delta body prograding into the basin from Most - Teplice Palaeohigh during TUR1. Detailed study of the sedimentary structures in the outcrops show high degree of reworking of foresets by tidal generated current. Two main directions of the paleocurrents results from the analysis - dominant current to the NW and subordinate current to the SE - SSE.
|
|
|
Flooding of the Hamr I mine and evaluation of the geological structure impact on the hydrogeological conditions in the northeastern part of Stráž block
Rozman, David ; Datel, Josef (advisor) ; Hrkal, Zbyněk (referee)
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....
|
|
|
Paleoecology of the Turonian Ostracoda from the Úpohlavy section
Houdková, Markéta ; Kyška Pipík, Radovan (advisor) ; Seko, Michal (referee)
This thesis deals with the class Ostracoda from the Úpohlavy quarry, which is an important paleontological site of the Turonian in the Czech Cretaceous Basin with abundant and well- preserved fauna. Twenty samples from marls and limestones of Jizera and Teplice formation were colected in which 36 marine middle and upper Turonian ostracods species were identified. Ostracods of the studied profile are characterized by gradual increase of species richness and decline of dominance of Cytherella cf. ovata (Roemer, 1840). The lowest diversity is in the Jizera formation and the highest diversity in the Teplice formation. The order Platycopida prevails on the order Podocopida in the Jizera formation, in which percentages of Platycopida is in the range 67-89%, while its percentage in the Teplice formatiion is lower in the range 25-59 %. Using the Platycopida Signal Hypothesis in a sense of Whatley et al. (2003), which compares percentages of Platycopida and Podocopida, a low O2 content in Jizera formation and in the Coprolite bed (monotonous dark marls) of Teplice formation is supposed. This is in accordance with low number of species (5-11 per sample) and with higher TOC content (0.34-0.74 %). With the beginning of limestone and marl sedimentation of the Teplice formation a number of species increases...
|
|
|
Karstification of carbonato-silicate rocks: review of literature and leaching experiments
Vojtíšek, Jan ; Bruthans, Jiří (advisor) ; Kůrková, Iva (referee)
The process of karstification doesn't occur only in easily soluble rock, such as limestone and evaporites, but also occurs in other rocks such as quartzites or siliciclastic rocks with carbonate cement. The "ghost rock" karstification is, unlike the classical karstification, two- step process, where the soluble component are dissolved first and subsequently the insoluble components are eroded and flushed away. These processes also occur in the Czech Republic, for example in the Bohemian Cretaceous Basin (BCB). Practical part of this thesis consists of leaching experiments of samples from BCB. Leaching in hydrochloric acid is an accelerated simulation of natural processes of dissolution by acidic solutions. Leaching of the samples in acid led to the decrease of sample strength, sometimes to their desintegration. The samples are probabbly prone to the evolution of karst conduits. Leaching experiments showed that the carbonate content is an important but not the only driving factor in the karstification process.
|
|
|
Palaeoecological aspects of Rhynchostreon Bayle oyster evolution
Rantuch, Jakub ; Košťák, Martin (advisor) ; Juřičková, Lucie (referee)
This paper presents a multilevel analysis of palaeoecological aspects of the process of the Rhynchostreon genera evolution. According to the latest results of research, the process of genus appears to be more dynamic than previously assumed.The processes of internal dynamics of the environment in conjuncture with other studied aspects of the late cretaceous environment (e.g. paleotemperature, salinity, etc.) were a significant factor that initiated the activity of selective pressure and represents an important factor in group evolution. In this work we provide the overall hypothesis about co-evolution of two intrageneric (sisters) lineages in Rhynchostreon genera. The definiton of evolutionary trends of intrageneric lineages within the presented hypothesis (including a new description of oyster species) is supported by various analytical methods, which anchors them in the current zoological nomenclature system. An electron microscopy, isotopes and biometrical analysis of a shell in cooperation with some of the sedimentologic methods suggest a relation of lithology (as a result of environmental aspect) and evolution process. The transregional concept of proposed ecological-evolutionary models, based on materials studies from various paleogeographic regions of cretaceous world, increases the...
|
guest ::
