Minerály těžké frakce arkózových pískovců z Tismic u Českého Brodu (perm blanické brázdy, Česká republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 337-350
Author(s):  
Zdeněk Dolníček ◽  
Jana Ulmanová
Keyword(s):  
Czech Republic ◽  
Chemical Composition ◽  
Bohemian Massif ◽  
Sedimentary Basin ◽  
Hydrothermal Activity ◽  
Heavy Mineral ◽  
Burial Diagenesis ◽  
Crystalline Complex ◽  
Variable Chemical ◽  
Tio2 Phase

The heavy mineral concentrate originating from Permian freshwater sandstones/arkoses from the Tismice site (northern part of the Blanice Furrow, Bohemian Massif, Czech Republic) was studied in terms of mineral composition and chemical composition of selected phases. Ilmenite, to various degree altered to a TiO2 phase and/or unidentified non-stoichiometric Fe-Ti (hydro)oxides, is the predominating constituent of heavy mineral fraction. Garnet, tourmaline, apatite and baryte are subordinate components. Garnet (with commonly etched “drusy” surface) belongs exclusively to almandine (Alm45-91Prp4-27Sps1-32Grs0-17Adr0-5). Tourmaline has variable chemical composition, but oxy-dravite prevails. Accessory phases include biotite, REE-rich goyazite (Goy45-59Flo29-43Cra11-17Gor0-1), zircon, pyrite, limonite, gahnite (Ghn57-68Hrc21-32Spl7-10Mgt1-2Gal1), staurolite, xenotime and monazite. Baryte and goyazite were likely formed during diagenesis of the host sediments or during later hydrothermal activity. Detrital garnet and tourmaline were probably sourced from the granulites, mica schists and migmatites of the Malín segment of the neighbouring Kutná Hora Crystalline Complex (KHCC). Surprisingly, amphibolites or serpentinites, frequently present in areas of the KHCC more proximal to the Permian sedimentary basin, did not contribute their garnets. We suggest that these areas were not exposed to erosion during the Permian period. Spectacular etching of surface of garnets and pervasive alteration of ilmenite were associated with burial diagenesis of the host sediments.

scholarly journals Fosfohedyfán z opuštěného železnorudného ložiska Hraničná (Slezsko, Česká republika)

2020 ◽  
Vol 28 (1) ◽  
pp. 44-47
Author(s):  
Jakub Jirásek ◽  
Dalibor Matýsek ◽  
Aneta Minaříková
Keyword(s):  
Czech Republic ◽  
Bohemian Massif ◽  
Metamorphic Rocks ◽  
High Grade ◽  
Chemical Formula ◽  
Charge Balance ◽  
Skarn Deposit ◽  
Crystalline Complex ◽  
The Czech Republic

Abandoned iron skarn deposit Hraničná is located 16 km NW of Jeseník, Silesia, Czech Republic. It is situated in the Staré Město Crystalline Complex, belt of high grade metamorphic rocks, which suppose to be a meta-ophiolite of the initial Cambro-Ordovican rifting. The deposit itself is formed by two stratiform magnetite-hematite bands within the marbles and quartz-rich biotite gneisses. Marbles containing silicates are rich in Zn and Pb and give evidence for sedimentary of volcanosedimentary origin of the ore accumulation. We collected several samples at the adit and +20 m levels of the mine which yielded phosphohedyphane. Mineral forms irregular aggregates up to 100 μm within the calcite-dolomite-magnetite skarn. Its average chemical formula from 7 WDS spots is (Ca2.07Sr0.03Ba0.01Mg0.02Pb3.23Zn0.01Fe0.09Al0.01)Σ5.47[(PO4)2.53(AsO4)0.03(SO3)0.01(SiO4)0.24]Σ2.81[Cl1.05F0.20]Σ1.25 based on 13 O+Cl+F. Use of the normalization to Ca1 + Ca2 = 5 and employing the charge balance could lead to the possible presence of (CO3)2- up to 0.60 apfu, resp. 3.61 hm. % CO2; this possible content do not have any effect on mineral classification. It is, therefore, fifth reported occurrence of this mineral in the territory of the Czech Republic and the Bohemian Massif.

The earliest ostracods from the Ordovician of the Prague Basin, Czech Republic

2014 ◽  
Vol 64 (4) ◽  
pp. 367-392 ◽  
Author(s):  
Karolína Lajblová ◽  
Petr Kraft
Keyword(s):  
Czech Republic ◽  
Bohemian Massif ◽  
Massif Central ◽  
Central European ◽  
Middle Ordovician ◽  
Prague Basin ◽  
Barrandian Area ◽  
Fossil Assemblages ◽  
European Variscides

Abstract The earliest ostracods from the Bohemian Massif (Central European Variscides) have been recorded from the Middle Ordovician of the Prague Basin (Barrandian area), in the upper Klabava Formation, and became an abundant component of fossil assemblages in the overlying Šarka Formation. Both early ostracod associations consist of eight species in total, representing mainly eridostracans, palaeocopids, and binodicopids. The revision, description, or redescription of all species and their distribution in the basin is provided. Their diversification patterns and palaeogeographical relationships to ostracod assemblages from other regions are discussed.

Mollusc successions reveal northward postglacial shifts of Alpine species ranges (Bohemian Massif, Czech Republic)

The Holocene ◽  
2021 ◽  
pp. 095968362110116
Author(s):  
Lucie Juřičková ◽  
Jakub Menšík ◽  
Jitka Horáčková ◽  
Vojen Ložek
Keyword(s):  
Czech Republic ◽  
Bohemian Massif ◽  
Late Glacial ◽  
Glacial Refugia ◽  
Land Snails ◽  
Glacial Refugium ◽  
Local Climate ◽  
The Alps ◽  
Species Groups ◽  
Late Glacial And Holocene

The Alps are an important hotspot of species diversity and endemism, as well as a presumed glacial refugium of several species’ groups including land snails. The recent ranges of Alpine endemics are well known, but their fluctuations during the postglacial period mirroring local climate changes are understudied. By analysing five Late Glacial and Holocene mollusc successions from two areas in the southernmost part of the Bohemian Massif (Czech Republic) situated about 100 km north of the Alps, we reveal details of these fluctuations. The Alpine endemic rocky dweller Chilostoma achates had reached the southern part of the Bohemian Massif already in the Late Glacial and disappeared in the Mid-Holocene canopy forest optimum. On the contrary, the northern boundaries of Alpine canopy forest epigeic snails extended further north than today at the turn of the Middle and Late-Holocene, pointing to a more favourable forest microclimate. The earliest known occurrences of several temperate canopy forest central European species, especially Causa holosericea and Discus perspectivus, imply the role of different areas in the Alps as their glacial refugia.

Petrogenesis of Cenozoic high-Mg (picritic) volcanic rocks in the České středohoří Mts. (Bohemian Massif, Czech Republic)

2021 ◽  
Author(s):  
Lukáš Krmíček ◽  
Jaromír Ulrych ◽  
Emil Jelínek ◽  
Roman Skála ◽  
Simona Krmíčková ◽  
...  
Keyword(s):  
Czech Republic ◽  
Bohemian Massif ◽  
Volcanic Rocks

Pb-Sb zrudnění z Antimonitové žíly, důl Rudolf, Bohutín (Česká republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 275-280
Author(s):  
Pavel Škácha ◽  
Jiří Sejkora
Keyword(s):  
Czech Republic ◽  
Chemical Composition ◽  
Empirical Formula ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Ore District ◽  
Archive Material

The Pb-Sb mineralization with dominant stibnite and plagionite and associated semseyite and zinkenite was found in an archive material collected at the Antimonitová vein, Bohutín, Březové Hory ore district (Czech Republic). Plagionite forms subhedral aggregates up to 1 mm in size. The unit-cell parameters of plagionite for monoclinic space group C2/c refined from the X-ray powder data are: a 13.4890(17), b 11.8670(14), c 19.997(2) Å, β 107.199(8)° and V 3057.9(6) Å3. Its chemical composition (average of 26 analyses, based on 30 apfu) corresponds to the empirical formula Pb5.02Sb8.15S16.82. Associated zinkenite is forming subhedral crystals up to 1 mm in size. Its empirical formula can be expressed as (Cu0.25Ag0.02Fe0.01)Σ0.28Pb9.22Sb22.19S41.31 (average of 26 analyses, based on 73 apfu). Semseyite aggregates have the empirical formula (Pb8.72Fe0.14)8.86Sb8.42S20.73 (average of 11 analyses, based on 38 apfu).

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