Vývoj akrečních orogenních systémů - povaha a geodynamika Západního Mongolského Altaje

Soejono, Igor

Long-lived accretionary evolution of the Mongolian part of the Central Asian Orogenic Belt was intensively studied during the last decades, however, it is not completely known yet. Types of geodynamic processes forming this orogenic system and their timing are addressed through petrological, geochemical and/or sedimentological study combined with U-Pb zircon geochronology. The publications included in this thesis present research of two magmatic and one sedimentary system in the western Mongolia. Both the ancient magmatic complexes and sedimentary successions provide opportunity to study geotectonic evolution in a different way. Therefore, mutually combined results of these two geological disciplines allow more complex insight into the geodynamics of the region. The geochemical, isotopic and geochronological investigations of the high-grade basement complexes in the eastern Hovd Zone reveal an existence of the Early-Mid-Ordovician intra- oceanic arc and associated fore-arc volcano-sedimentary complex. The superimposed Mid- Silurian intra-plate magmatism is interpreted as a result of lithospheric thinning related to the same but already retreating subduction. Striking similarities of the studied basement with neighbouring Lake Zone margin suggest that the both units originally belonged to a single...

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