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Geochemistry and origin of skarns of the Bohemian Massif
Bubal, Jan ; Dolejš, David (advisor) ; Houzar, Stanislav (referee)
Calcic-iron skarns are one of the characteristic part of the regional metamorphic complexes of the Bohemian Massif. Their mineral assemblages, structures and significant enrichment of Ca, Al and Fe were previously interpreted to be primary (exhalation sediment) or secondary (metasomatic carbonates). In this project, which consists of three sub-studies will focus on the geochemical composition of skarn as the main arguments for the discussion of their origin. Malešov deposit belongs to the typical calcic-iron skarns whose mineral assemblages are not very different from similar skarns associations in the Bohemian massif. It consists of lenticular body that is stored in gneiss and migmatites of the Kutná Hora crystalline complex. On the deposit prevails garnet-pyroxen skarn, less abundantly represented garnet and magnetite skarns and skarns replacement by amphibole or epidote. Fine-grained garnet skarns are formed by isotropic dark red garnet (Adr78-88Prp0-0.3), while in massive garnet rocks garnet grains form the core (Adr13-38Prp2.5), which envelop newly formed garnet (Adr28-66Prp1.6). In association with them is often pyroxene (Hd60-90) which can be replaced by hastingsite amphibole composition. Other minerals present are magnetite, Fe-epidote, calcite and albite. Magnetite and pyroxene skarns are...
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Distribution of trace elements in tectites with using LA ICP-MS
Svatá, Adéla ; Strnad, Ladislav (advisor) ; Houzar, Stanislav (referee)
The following example deals with methods of determining major and trace elements in a particular special kind of natural glasses - tektites. Measurements were performed on seventeen samples. Two of them belonged to a group of Libyan desert glass and the remaining fifteen were originally from the Australasian tektite field. For these purposes, optical microscopy was used in the preparatory phase of study of the samples. The studied samples were prepared in the form of cross-sections. Microscopy was employed to ensure the correctness of the procedure for selecting appropriate samples and precise areas of cross-sections that are suitable for analysis. The main elements were determined by electron microanalysis. The values obtained in these measurements confirmed existing knowledge about the composition of tektites. The chemistry of Libyan desert glass corresponded to 98 weight percent of SiO2. In the Australian-Asian samples, this value was equal to 73 wt.%. The other major oxides include Al2O3, FeO, MgO, etc. The contents of these elements in the Libyan desert glass were determined in the range of 0.154 to 0.727 percent by weight. The Australasian tektites contained 0.598 to 0.875 wt.% of these elements. The most important data were obtained by inductively coupled plasma mass spectrometric (ICP-MS)...
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Petrogenesis and emplacement of post-collisional granitoids of southeastern Moldanubian Batholith
Hájek, Tadeáš ; Verner, Kryštof (advisor) ; Houzar, Stanislav (referee)
The Weinsberg Composite Pluton, located in the southern part of the Moldanubian Batholith is a large intrusive body with complex internal fabrics, petrogenesis and emplacement processes. On the basis of geochemistry and zircon morphology classification the dominating lithology in the northeastern part of the pluton seems to be the second type of the Weinsberg granitoids (WbG II). Based on the integration of the structural, petrological and geochemical data set acquired from the investigated area, the interpretation of geodynamic evolution and emplacement of the eastern part of the Weinsberg Pluton could be proposed. This interpretation invokes: (a) indentation and underthrusting of a continental microplate (Brunia) in the east at around ~340-330 Ma, driving mantle delamination and subsequent heating and anatexis in the metapelitic lower crust as the heterogeneous source for Weinsberg- and Eisgarn-types of granitoids; (b) subsequent growth of a large metamorphic dome along the edge of the Brunia indentor followed by polyphase emplacement of entire eastern part of the Moldanubian Batholith around ~330-325 Ma including the Weinsberg Composite Pluton in the south; (c) increasing role of the N-S shortening and associated NW-SE dextral shearing along localized shear zones which caused the prevailing...
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Geochemistry and origin of skarns of the Bohemian Massif
Bubal, Jan ; Dolejš, David (advisor) ; Houzar, Stanislav (referee)
Calcic-iron skarns are one of the characteristic part of the regional metamorphic complexes of the Bohemian Massif. Their mineral assemblages, structures and significant enrichment of Ca, Al and Fe were previously interpreted to be primary (exhalation sediment) or secondary (metasomatic carbonates). In this project, which consists of three sub-studies will focus on the geochemical composition of skarn as the main arguments for the discussion of their origin. Malešov deposit belongs to the typical calcic-iron skarns whose mineral assemblages are not very different from similar skarns associations in the Bohemian massif. It consists of lenticular body that is stored in gneiss and migmatites of the Kutná Hora crystalline complex. On the deposit prevails garnet-pyroxen skarn, less abundantly represented garnet and magnetite skarns and skarns replacement by amphibole or epidote. Fine-grained garnet skarns are formed by isotropic dark red garnet (Adr78-88Prp0-0.3), while in massive garnet rocks garnet grains form the core (Adr13-38Prp2.5), which envelop newly formed garnet (Adr28-66Prp1.6). In association with them is often pyroxene (Hd60-90) which can be replaced by hastingsite amphibole composition. Other minerals present are magnetite, Fe-epidote, calcite and albite. Magnetite and pyroxene skarns are...
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Distribution of trace elements in tectites with using LA ICP-MS
Svatá, Adéla ; Strnad, Ladislav (advisor) ; Houzar, Stanislav (referee)
The following example deals with methods of determining major and trace elements in a particular special kind of natural glasses - tektites. Measurements were performed on seventeen samples. Two of them belonged to a group of Libyan desert glass and the remaining fifteen were originally from the Australasian tektite field. For these purposes, optical microscopy was used in the preparatory phase of study of the samples. The studied samples were prepared in the form of cross-sections. Microscopy was employed to ensure the correctness of the procedure for selecting appropriate samples and precise areas of cross-sections that are suitable for analysis. The main elements were determined by electron microanalysis. The values obtained in these measurements confirmed existing knowledge about the composition of tektites. The chemistry of Libyan desert glass corresponded to 98 weight percent of SiO2. In the Australian-Asian samples, this value was equal to 73 wt.%. The other major oxides include Al2O3, FeO, MgO, etc. The contents of these elements in the Libyan desert glass were determined in the range of 0.154 to 0.727 percent by weight. The Australasian tektites contained 0.598 to 0.875 wt.% of these elements. The most important data were obtained by inductively coupled plasma mass spectrometric (ICP-MS)...
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