Geochronology and Geodynamic Settings of Metamorphic Complexes in the Southwestern Part of the Tuva-Mongolian Terrane, Central Asian Foldbelt

U–Th–Pb geochronological (LA-ICP-MS) stady the detritе zircons from the Late Cainozoic sands of the Olkhon island (the Baikal rift zone) were performed. It is shown that the early Paleozoic magmatic and metamorphic complexes of the Olkhon terrein of the Central Asian Mobile Belt and the Late Carbonian – the Early Permian granitoids of the Angaro-Vitimsky batholith were the main their sources. Transfer of granitoids of the Angaro- Vitimsky batholith were the main their sources. Transfer of the last was carried out on distance not less than 100 km. The assumption is made that it happened by powerful air transfer, and including on ice of Baikal Lake.

AbstractJurassic mélange complexes related to the subduction of the Neotethys Ocean occur in the Bükk Mountains, North Hungary. This paper characterizes the sedimentary sequence of basin and slope facies that occur in the southwestern part of the Bükk Mountains, placing special emphasis on the redeposited sedimentary rocks (olistostromes, olistoliths: Mónosbél Group) in order to obtain information on the provenance of the clasts, and the mode and time of their redeposition. The series of formations studied shows a general coarsening-upwards trend. Based on radiolarians and foraminifera, the Mónosbél Group formed in Early to Late Bathonian time. The lower part of the complex is typified by a predominance of pelagic carbonates, shale and radiolarite with andesitic volcaniclastic intercalations. The higher part of the succession is characterized by polymictic olistostromes. Large olistoliths that are predominantly blocks of Bathonian shallow marine limestone (Bükkzsérc Limestone) appear in the upper part of the sequence. Based on the biostratigraphic and sedimentological data, results of analyses of the redeposited clasts and taking into consideration the concepts of the development of the western Neotethys domain, the evolutionary stages of the sedimentary basins were defined. The onset of the compressional stage led to initiation of nappe stacking that led to the formation of polymict olistostromes and then to the redeposition of large blocks derived from out-of-sequence nappes of the former platform foreland.