|
|
Geophysical exploration of supposed maar volcanoes in Western Bohemia
Turjaková, Veronika ; Valenta, Jan (advisor) ; Skácelová, Zuzana (referee)
We were investigating two localities of supposed maar volcanoes, Ztracený rybník and Bažina, which can be found at the western margin of the Eger rift on the presumed line of the Tachov fault. The Eger rift was abundant in volcanic activity during Tertiary and still is a seismoactive zone with distinct post- volcanic features. The examined structures are distinct morphological depressions (ca. 30 m deep and several hundreds meters wide) with a circular shape which is characteristic for maar structures. We studied the locality using a complex of geophysical methods: a ground magnetometry, electric resistivity tomography and a time-domain electromagnetic sounding. The results showed a circular rim of high resistivities around the depressions and approximately 100 m of sediments filling the depression. Moreover, we have mapped a negative magnetic anomaly in the lesser of these two structures (Bažina) indicating a basic intrusion that got close to the surface. Moreover, we have observed the intrusion on the resistivity data as well. Therefore, we can suggest that these two structures are diatremes created during the phreatomagmatic eruption. The lesser maar (Bažina) erupted during the reversed geomagnetic field.
|
|
|
Srovnání vybraných realizací parkových a zahradních exteriérů z hlediska použití dekoračního a stavebního kamene
Skácelová, Zuzana
Garden and landscape architecture use a lot of constructional and ornamental stones, but visitors or owners can't see it necessary for first sight. Investors doesn't know if stone elements are reasonably priced and constructors can use wrong technology, because there is no good professional literature about this theme. This thesis analyse four special stone gardens and is iterested in their financial intensity and technical difficultness. The results of the thesis are made up from analyses of the stone gardens and informations obtained by garden engineers and stonemasons.
|
|
|
Geophysical prospection of volcanic structures, in the area of Rybí loučky, Jizerské mountains
Fait, Václav ; Valenta, Jan (advisor) ; Skácelová, Zuzana (referee)
This thesis briefly depicts fundamental principles of three geophysical methods (gravimetry, magnetometry and electrical resistivity profiling), which had been used during research at the Rybí lou ky site in order to clarify local geological conditions. Furthermore, the reader gets acquainted with formation of a maar-diatreme, which is thought to be present at the researched site. The next part describes principles of field measurements and the procedure for evaluation of results. The results are graphically plotted in the last part. Also, the results are compared to previous investigations conducted at this site. Geophysical measurements showed that geological structures on the Rybí lou ky site are much more complex than expected. The simple diatreme structure is most likely not applicable in this case. In contrast, it is not a structure formed solely by a glacier. The origin is most likely a combination of tectonic predisposition, volcanic activity and subsequent selective erosion.
|
|
|
Geophysical survey of subsurface voids at locality Letonice
Bartášková, Lucie ; Blecha, Vratislav (advisor) ; Skácelová, Zuzana (referee)
The Větrníky national nature reserve, located in the South Moravian region north of the village of Letonice, is one of the largest steppe reserves in Southern Moravia. This whole area is characterized by the presence of both stable and active landslides, and the occurrence of suffosion sinkholes has been monitored there in the long-term. The aim of the thesis was to investigate whether it was possible to observe subsurface phenomena, caused by the washing out of fine rock particles by ground water, by means of geophysical methods. This phenomenon is known as suffosion. The measurements took place in the areas where the suffosion manifestation was very distinctive, that is around two sinkholes that were visible on the surface. In order to identify the suffosion structural-geological causes and their manifestations at a given location, the gravimetric and electrical resistivity tomography (ERT) methods were used in the first stage of the research. Measured data was further processed and geologically interpreted. The gravimetric method has proved suitable when identifying rocks affected by suffosion, in which case we assume that their density is lower than the density of the surrounding rocks. Using the ERT method, it was possible, in the vertical profile, to distinguish the sandy-gravelly sediments...
|
guest ::
RSS feed.