Geology of the Western Carpathians
The Western Carpathians are an arc-shaped mountain range, the northern branch of the Alpine-Himalayan fold and thrust system called the Alpide belt, which evolved during the Alpine orogeny.
The geological evolution of individual parts of the chain is complex, a result of tectonic processes like folding, thrusting and the formation of sedimentary basins of various types during the Mesozoic and Cenozoic.
Many aspects of the geological structure of the Western Carpathians have not been completely studied and are subject to ongoing research and debate.
The Western Carpathians are separated from the Alps by the valley of the river Danube (only from the geographical point of view; the geological boundary is the so-called Carnuntum gate) and the Raaba line.
The second important suture is called the Peri-Pieninic lineament, roughly copying the structure of Pieniny Klippen Belt.
Deeper under the sediments it constitutes the boundary between the Central Carpathian basement rocks and the foreland – the Bohemian Massif and East European craton (Podolia platform).
The whole zone of the foredeep is developed in the foreland of the Alps, and runs through the Moravia to the Ostrava Basin and further East to Poland, Ukraine, and Romania.
The Pieniny Klippen Belt is a relatively thin but important dividing line separating the Outer Western Carpathians from the internal zones of orogeny.
In their predominantly crystalline basement zones called the Tatric, Veporic, and Gemeric, thrusting (thick-skinned) is also present, but not as apparent.
Relatively thin and complicated, the Pieniny Klippen Belt creates a boundary, a tectonic suture, between the Outer and Central Western Carpathians.
Complicated arrangement of particular tectonic units was later affected by strike-slip motion in the area of the Peri-Pieniny Lineament in the Miocene.
Consequent erosion dissected the rigid limestone tectonic lenses to the shape of protruding klippes (e.g. Vršatské bradlá in Western Slovakia).
The zone of klippes stretches almost uninterrupted from the Podbranč in Western Slovakia to the Poiana Botizei in Northeastern Romanian.
Nappes are large slabs of the Mesozoic carbonate rock with similar sedimentary sequence as present in the Tatric cover.
[4] The Hronic is typical with the occurrence of Permian andesitic-basalts[4] (so called Ipoltica Group) and a larger thickness of variable Triassic carbonate rock.
The Southern row of core mountains includes the Tríbeč Mts., Žiar Mts., Veľká Fatra Mts., Chočské vrchy Mts., The Eastern part of Nízke Tatry Mts.
Crystalline basement rock is most abundant in this area, and the largest granitic pluton in the Western Carpathians is present here.
Other problem of exact definition of boundary between the Internal and Central Western Carpathians are views of the structure of the Meliatic unit.
The Internal Western Carpathians are composed generally of the tectonic units originating from the area of the former Meliata-Halstatt Ocean or South of it.
There are large nappes of Mesozoic carbonates (Silicic, Meliatic, Tornaic), which are not affected by metamorphism and are characteristic with typical affinity to the South Alps-Dinaride facies.
The principal structural unit of the belt is Meliatic, composed of rocks of the subduction mélange – deep water shales, radiolarites, basalts of oceanic type and marbles.
To the south of the previous area there is the Bükkic unit, which bears the signs of the transitional zone between the Western Carpathians and the Dinarides.
[10] A tectonic unit of uncertain position is the Zemplinic in the horst of the Zemplín Mts., emerging from the Cenozoic sedimentary fill of the Eastern Slovakia Basin.
They are composed of the paragneisses, amphibolites, and migmatites, together with Post-Hercynian Carboniferous and Permian conglomerates and thin beds of black coal.
[12] The oldest forms of volcanism, which affected the area of the Western Carpathians, are hardly recognized because of later tectonic processes and destruction by erosion.
[14] Large volumes of volcanic rock, considered a product of stratovolcanos, significantly changed by metamorphism, are present in the Gemeric.
Three main phases of the volcanic activity are distinguished: The occurrence of metamorphosed crystalline rock in the Western Carpathians is known from the Tatric, Veporic, Gemeric, and Zemplinic zones.
Signs of the Alpine metamorphism, which took place 75–107 million years ago, are well preserved in the Mesozoic formations of the Tatric, Gemeric, and especially Veporic.
The Quaternary glaciations identified in the Western Carpathians are, from oldest to youngest: Donau, Günz, Mindel, Riss and Würm.
[22] During these glaciations glaciers extender downhill from the High Tatras and nonglaciated uplands were subject to frost weathering and solifluction.
