|
|
Nature of magnetic anomalies on Moon, sample analysis
Kameníková, Tereza ; Kletetschka, Günther (advisor) ; Blecha, Vratislav (referee)
The magnetic properties of a rocks on Earth are mostly well known. But what is the magnetic properties of a rocks which originate extraterrestrial? Such as on Moon. We are interested in the intensity of paleofield of some Moon rocks which were chipped by Apollo 15 in early 70s. The text is an unification of the basic knowledge of a magnetism, the way how it originates. You can found here also the basics of paleomagnetism and methods how the rocks can get own magnetisation, their properties and some outline how the Moon rocks can get own magnetisation if moon doesn't have a dynamo. Then we summaries the information got from measurements of two Moon rocks 15404.219 and 15445.277, which were divided to subsamples and measured in Paleomagnetic laboratory in Czech Academy of Sciences. Each subsample was measured separately on 2G cryogenic magnetometer. We were interested in AF (alternating field) remanent magnetisation spectra from which we got an estimating intensity of paleofield from which the samples got own magnetisation. The final part is devoted to discussion on topic of possible existence of lunar dynamo or other possibilities how the Moon rocks can have held the magnetisation.
|
|
|
Application of environmental magnetic techniques in Quaternary sediment study
Žatecká, Michaela ; Kadlec, Jaroslav (advisor) ; Kletetschka, Günther (referee)
5 ABSTRACT: The Bachelor Thesis presents basic principles of the environmental magnetic methods and their applications in paleoenvironmental reconstructions from Quaternary sedimentary archives. Description of mineral and rock magnetic principles follows after an introductory sketch of historical development of the environmental magnetic topic. Next part of the thesis is focused on explanation of basic principles of the environmental magnetic methods and application magnetic history of the sedimentary rocks: namely different kinds of magnetic susceptibility, anisotropy of magnetic susceptibility, remanent magnetization and hysteretic parameters of the sediments. Application of the environmental magnetic methods enables interpretation of depositional and/or post- depositional history (e.g., directions of wind or water currents transporting clastic sediments) or intensity of geochemical weathering (connected with pedogenesis) which is directly controlled by climatic conditions and their changes. Examples of application of the environmental magnetic methods in paleoenvironmental research of the deep ocean, lacustrine and eolian natural archives are described in the final part of the thesis. Key words: environmental magnetism, paleoenvironmental reconstruction, sedimentary archives, Quaternary
|
|
|
Frequency changes in normal and reversed polarities of geomagnetic field
Olšanská, Irena ; Kletetschka, Günther (advisor) ; Pruner, Petr (referee)
This work consits of two parts, literature review and practical section. Literature review covers essential knowledge about magnetic field of Earth in attempt of understanding its inversion events. This section contains thistory of research of geomagnetism, key theories, physical quantities, magnetic properties of the minerals and outlines the knowledge of paleomagnetism. Practical part concerns the analysis of geomagnetic field inversions. It deals with inversions that happened during the last 157, 53 million years (Gee and Kent, 2007) and compares the duration of normal and reversal polarity and both types together. Statistical methods of investigation,namely Gaussian distribution and frequency, were employed. The evaluation of results showed that the average time between two inversions is: 124 000 years for normal, 450 000 years for reversal and 287 000 years for both types. The intervals shortened over last 80 million years. Comparing the frequencies of each period following results were obtained: both types usually lasts about 350 000 years, periods that are shorter than 350 000 years appears more often for normal polarity, but the frequencies of longer periods are similar for both types.
|
|
|
Prerequisites for building magnetometer out of carbon nanotubes for geological applications
Mazanec, Martin ; Kletetschka, Günther (advisor) ; Kohout, Tomáš (referee)
This thesis is the first step in a long-therm project with object to built magnetometer from carbon nanotubes. At the beginning of the thesis is introduction to magnetism and its basic physical characteristics, brief description of the Earth's magnetic field, some magnetic minerals and material behavior in a magnetic filed. All this in a geological context. In the second part I focus on the measurment of the magnetic field, especially on some specific device. The third part deals with the allotrope of carbon - graphene structures. It offers a brief overview of thein properties, one chapter about the productiona and possible use. In discussion I try to combine these parts with a specific purpose, which is the uso of carbon nanotubes in measuring the rock magnetism. We present a simplified funcion principle of the discussed device, the first steps of construction and inicial measurment.
|
|
|
Paleomagnetic record of basaltic lava flows on Nelson Island, Antarctica
Haislová, Radka ; Kletetschka, Günther (advisor) ; Pruner, Petr (referee)
Paleomagnetism is geophysical method for determination of former magnetic field orientation on the Earth using measurement of remanent magnetisation of rocks. Combined with radiomagnetic datingk paleomagnetism enables study of time evolution of the magnetic field on the Earth and/or reconstruction of former positions of litospheric plates. This thesis is elaborates on paleomagnetic record of basalt lava flow on the Nelson's Island in Antarctica and summarizes geological data. In the research part of this thesis theory of magnetism is introduced and the paleomagnetism method is emphasized. Additionaly, I provide a short review of magnetic minerals, that can occur in basalt. These mineral can potentialy hold some information about the character of magnetic field of the geological past. Radiometric dating methods are included as atool for determination of absolute age of solidification of ingenous rocks (lava). Specifically, the K-Ar and Ar-Ar dating methods are emphasized. The regional section of this thesis conntains geological overview about the Antarctica and the Nelson's Island with its surroundings.Included is a section about the laboratory devices for measuring vector magnetisation of oriented rock samples (for example rotational and cryogenic magnetometer). The thesis is concluded with its...
|
|
|
Magnetic properties of the spherules from sediment in Tunguska (holocene) and North America (holocene/pleistocene)
Nábělek, Ladislav ; Kletetschka, Günther (advisor) ; Rajmon, David (referee)
In the early 20th century, 30 June 1908, the event took place, which is described as the Tunguska Event, or Tunguska. It is still not entirely clear what happened that day and the whole event was caused. The causes of events Clovis which is dated to the Younger Dryas (YD) are not entirely clear. In this period there was a sharp slowdown, which resulted in the extinction of large mammals. The link between the two events is the discovery of magnetic spherules in the sediment layer. This material may arise in several ways: fossil fuel combustion processes, ablation of cosmic material passing through the atmosphere, a large explosion in the atmosphere or atmospheric discharges (lightning). This thesis deals with analysis and Tunguska Event and Clovis event, and related research microscopic spherules (material of uncertain origin) found after the events in a layer of sediment in North America and central Siberia. The object is to compare the two events and causes of based on research and laboratory measurements of material from Clovis and Tunguska. For the analysis of magnetic spherules status was gained by the non-magnetic separation. The material was measured residual magnetization. The measurements were used magnetic scanner. On the basis of laboratory measurements of magnetic properties of spherules...
|
|
|
Modeling of meteorite impact
Takáč, Marian ; Kletetschka, Günther (advisor) ; Kohout, Tomáš (referee)
In Febuary 2013, in spectacular light and sound accompaintmen a meteorite hit the Russian Federation. Small fragment which landed in populated areas caused together with blust wave damage. The largest part broke the ice crust on the lake in outskirts of Chebarkul. The circular shaped hole gave rise to various conspiracy theories. About half of the year after impact the meteorite was lifted and conspiracy theories boken. The event immediately raised interest in the issue of the impacts of meteorites and phenomena associated with them. Processes when the meteor is passing trough atmosphere, impact craters, their origin and characteristics, computer models, types of meteorites and their origin. Or just a mystery of the hole in the ice crust of the lake Chebarkul. Science has got answers for such toppics. This paper is just trying to summarize them.
|
|
|
Thermal relations leading to the formation of gaseous phase within the ice covering lakes and ponds
Hrubá, Jolana ; Kletetschka, Günther (advisor) ; Dědeček, Petr (referee)
When cutting an ice from lakes and ponds gaseous phase displays often ubiquitous bubble textures along the ice thickness. The occurrence of bubbles (enclosures filled with the gas) in ice relates to a content of the dissolved gas in the lake/pond water prior to freezing over the surface. When water freezes, dissolved gases are rejected and redistributed at the ice-water interface, depending on the saturation ratio between the gas and water. If the concentration of dissolved gases surpasses a critical value (as freezing progresses), the water at the interface becomes supersaturated, and gas bubbles nucleate and grow to a visible size along the interface. The bubbles generated at the ice-water interface are either incorporated into the ice crystal as the ice-water interface advances, thus forming gas pores in the ice, or released from the interface. If there is incorporation or release is determined by several factors. The bubbles nucleated at the advancing ice-water interface may be characterized by concentration, shape, and size, which depend on growth rate of ice, the amount of gases dissolved in water, and the particulate content of water. This work focused on the relation between growth rates of the ice and the occurrence of bubbles in the pond ice. I monitored the temperature of the ice formed...
|
|
|
Magnetic survey in Pruhonice park
Bartášková, Lucie ; Kletetschka, Günther (advisor) ; Blecha, Vratislav (referee)
The aim of the thesis was to get acquainted with the measurement of the magnetic field of the earth on a concrete example, in Průhonice Park, where the geological structures are covered pond, and there is direct access to rock. It was also proposed vessel for measuring the magnetic field on the surface of the water. The measurement result was compared with existing geological maps and interpreted in terms of magnetic sources. On the basis of familiarity with the course of magnetometric data acquisition and processing the earth was proposed procedure for measuring the magnetic field of the planet Mars. Powered by TCPDF (www.tcpdf.org)
|
guest ::
