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Home > Science and research > Structure, Composition and Evolution of the Earth's Crust > Plutonic rocks

Plutonic rocks

Plutonic rocks are formed when bodies of molten magma crystallize and solidify at depths greater than 1km below the Earth’s surface. Such melts consist of silicate material derived partly from the crust and partly from the mantle of the Earth. The mineral composition of the plutonic rock is determined by the proportions of material derived from these different sources.

The granitic plutons that have formed in the territory of the Czech Republic are of exceptionally large volume and were emplaced and crystallized over an extended period of geological time. The oldest originate from a time before 2.1 Ga (thousands of millions of years) and a smaller number date from the oldest Palaeozoic before 550-450 Ma. However, the great majority of granitoid intrusions were emplaced during the Variscan orogeny.

Microscopic study of rock-forming minerals

Microscopic study of rock-forming minerals

Structural and petrological investigations of magmatic complexes are carried out across the Czech Republic in order to determine the patterns of distribution and mechanisms of emplacement of different types of plutonic rock. The aim is to reconstruct the sequence of geodynamic and thermal events that governed magmatic processes during the Cambro-Ordovician, and to understand how the intrusive complexes took shape. Experimental studies of thermal loading in the granodiorite intrusion at Mokrsko and detailed structural mapping and geotechnical monitoring of the water-supply tunnel near Bedřichov in the Izera Mountain, together with structural research on the Melechov granite massif, are examples of research into the long-term behavior of granitoid rocks so that numerical models of the stability of the rock environment can be developed. This has direct strategic applications in the construction of underground facilities e.g. repositories for radioactive waste, gas and CO2 reservoirs and geothermal energy.

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Czech Geological Survey
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