Geology of the Czech Republic
The geology of the Czech Republic is highly tectonically complex, split between the Western Carpathian Mountains and the Bohemian Massif.[1]
Geologic history
The geologic development of the territory of the Czech Republic was influenced by the cratonization of the Bohemian Massif at the end of the Permian. and with simultaneous orogenic activation of the Carpathian basement. Simultaneously, orogenic activity activated Carpathian basement.
The pre-Pan-African elements of the Bohemian Massif remain poorly understood because of their allochthonous position in Pan-African and Variscan units. The Svetlik orthogneiss in southern Bohemia is 2.1 billion years old and the Dobra granite gneiss is 1.37 billion years old. Together, they may be the oldest elements of the Bohemian Massif. The Svetlik orthogneiss occurring between the Monotonous and Varied Groups of the Moldanubicum might correspond to Gondwana-derived terrane (the Penteverian crust formed 2.1 billion years ago). The age of 1.37 billion year age of the Dobra Gneiss suggests possible origin as Laurentia or Baltica.
The Pan-African orogenic belt formed 800-570 million years), formed between Laurentia and Gondwana as well as microcontinent segments, can be traced to the Bohemian Massif. For instance, Precambrian metamorphic rocks act as a footwall of conglomerates from the early Cambrian conglomerates, formed the 550 to 580 million years ago in the Lugian Pluton, the 520 660 year old Ma Brno pluton is similar. Cadomian, Pan-African 600 million year old overprinting on zircons is found in many parts of Europe.
In addition to debates about the Pan-African orogeny, the Caledonian orogeny in the Bohemian Massif is poorly understood. In the Saxothuringicum area and in the major part of the Lugicum, there is no break at the Silurian-Devonian boundary. Sedimentary deposition began in the early Cambrian and in elsewhere in the Ordovician and ended by the mid-Carboniferous orogeny 330 to 320 million years ago. The few indications of the Silurian/Devonian hiatus in N Lugicum are not of regional significance. Higher ages of the amphibolites (ophiolite) complex of the Marinaska Lazne (486 Ma) point to an early Ordovician extension (Bowes and Aftalion, 1991, Medaris, Jelinek and Misaf 1994) and c. 500 Ma granite gneisses of the Lugicum (Kroner, Hegner and Jaeckel, 1994) early Ordovician magmatic activity, However, these ages have to be considered as minimum ones.
In the Brunovistulicum the transgression of early Devonian conglomerates on the pre-Devonian of rome precisely the Pan-African basement seaks favorably of its geotectonic independence on W units of the Bohemian Massif.
At the time of oceanic subduction of the Rhenohercynicum below the Saxothuringicum, areas of the Bohemian Massif were reworked. Moldanubicum rocks experienced very intensive reconstruction, producing mantle-crust interaction granulite and eclogite facies rocks. Nappe and shear tectonics appeared the Moldanubicum as it was joined with the Moravosilesicum and Brunovistulicum to other segments of the Bohemian Massif.
Mesozoic-Cenozoic (251 million years ago-present)
A platform cycle began at the Permian-Triassic boundary with periodic erosion and occasional marine transgressions into the late Cretaceous and Paleogene, coupled with alkali volcanic activity. Radial faulting during the Alpine orogeny took place. Pre-Triassic development of the Czech West Carphathians is related to the Brunovistulicums. The pre-Devonian basement and the sedimentary cover of the Brunovistulicum underlie the Mesozoic and Cenozoic formations in the West Carpathians. Limestone in the south are from the Triassic and Jurassic. To the north is an allochtonous ocean environment, to the north of the Klippen Belt. The Outer Flysch Carpathians formed after the main Carpathian Orogeny in the late Cretaceous, showing synorogenic sedimentary sequences from Cretaceous-Oligocene age that move northward as far as the Carpathian Foredeep. The last thrusting in late Miocene brought erosion, local uplifting and subsidence in Quaternary depressions. [2]
Natural resource geology
Resource such as silver, gold and iron ore have been mined since the Middle Ages. The Bohemian Massif and the Western Carpathians are the main metallogenic zones. The Bohemian Massif is characterized by icomplex, mostly epigenetic, mineralization of Variscan age including gold, tin, uranium, silver, lead, zinc and limited copper together black coal deposits from both the Carboniferous and Cenozoic. The West Carpathians have no resources. A few oil fields, such as the Hodonin field in the Vienna basin exist.
Moldanubian metallogenic province
Moldanubian metallogenic province covers most of the Moldanubicum. In the Moldanubian subprovince, lead and zinc form as vein deposits with silver in the aureole of the Central Moldanubian Pluton and Central Bohemian Pluton (including ore districts such as Kutna Hora, Prribram and Jihlava). Vein deposits of gold ores and the disseminated gold deposit at Mokrsko, south of Prague are limited to the western contact with the Central Bohemian Pluton. Uranium ore deposits in the Pribram district or near the contact of the Bohemicum-Moldanubicum, northeast of the Cesky les Tachov or at the contact of the Central Moldanubian Pluton have been investigated since the 1980s. An unusual zinc-copper ore deposit was mined in the last after 1982 in the Ransko gabbro-peridotite massif which also shows some nickel sulfide mineralization.
The Krkonose Mountains metallogenic subprovince in the Lugicoum area, centers on the Krkonose Pluton and the Orlicke hory Mountains-Klodzko subrovince. It has highly variable deposit of little economic importance including lead, zinc, copper and gold. [3]
References
- Moores, E.M.; Fairbridge, Rhodes W. (1997). Encyclopedia of European & Asian Regional Geology. Springer. p. 175–182.
- Moores, E.M.; Fairbridge, Rhodes W. 1997, p. 179-180.
- Moores, E.M.; Fairbridge, Rhodes W. 1997, p. 180-181.