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Paleomagnetism and magnetomineralogy of rocks from the Bohemian Massif and Tethyan Realm
Schnabl, Petr ; Pruner, Petr (advisor) ; Hrouda, František (referee) ; Petrovský, Eduard (referee)
Mgr. Petr Schnabl - Dissertation Paleomagnetism and magnetomineralogy of rocks from the Bohemian Massif and Tethyan Realm Abstract The thesis deals with paleomagnetic and rock magnetic properties of Silurian/Devonian and Jurassic/Cretaceous limestones, Paleogene/Neogene basaltic rocks and altered Silurian basalts. The main goal is to determine the history of the Earths' magnetic field from the Silurian to the present. Two lithostratigraphic formations are defined in the Jičín volcanic field on the basis of volcanology, paleomagnetism and radiometric dating. The Trosky Formation (24.6?/18.3 - 15.7 Ma) is composed of several Strombolian-type volcanoes, while the Kozákov Formation (5.2 - 4.6 Ma) is represented by effusive products with a crater vent of a single giant volcano. One Pliocene (4.3-3.3 Ma) and two Pleistocene phases (2.6 -2.1 Ma and 1.8 - 1.1 Ma) of volcanic activity Magnetostratigraphy is a very important tool for the definition of the J/K boundary. The boundary between the Crassicolaria and Calpionella zones is present within geopolarity zone M19n. The boundary between the ammonite zones Jacobi and Durangites also lies close to this point. Paleomagnetic directions of Silurian and Devonian rocks in the Bohemian Massif are very difficult to interpret and have been studied as a challenging problem...
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Magnetostratigraphic investigation of volcanic complex Úhošť hill(Doupovské hory Mts.)
Schnabl, Petr ; Cajz, Vladimír ; Chadima, Martin ; Rapprich, V. ; Šlechta, Stanislav ; Pruner, Petr
A detailed magnetostratigraphic study was carried out at the locality of Úhošť near Kadaň on the NE margin of the Doupovské hory volcanic complex. The majority of the samples had small viscous component that was possible demagnetized in the range 1 to 5mT or below 100°C. The primary components were pointing to the origin and were mostly interpreted in the range between 10 and 100mT or 100 to 560°C. The mean declination from all localities is 11.5 deg and inclination 53.9 deg. The parameter alpha 95 ranges between 2 and 10 degree. It's mean all lava flows has normal polarity. The major task is why all 13 localities have normal polarity although in the time range between the first and last volcanic event are several normal and reverse polarity periods.
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