We report new isotope dates and metallogenic and chemical characteristics of granitoids from the Hangayn area (central Mongolia) with implications for the time and tectonic settings of their formation. Proximal U-Pb and Ar-Ar ages of 241.3±1.5 Ma and 238.2±2.5 Ma have been obtained for the Triassic Guchin Us and Hurmen Gol intrusions, respectively, and an Early Permian age (288.7±2.3 Ma, Ar-Ar) for the Bayanulaan granite and for granite porphyry from the Saran Uul Cu-Mo-(Au) deposit. Granitoids of the Egiyn Davaa, Hangayn, and Shar Us Gol complexes in the southwestern Hangayn area are of two geochemical types. Some intrusions that were formerly attributed to these complexes have been reinterpreted as resulting from multiple plutonic pulses of different ages. According to our new data and published evidence, most of granitoids in the area may have been produced by Early-Middle Triassic (255–230 Ma) rather than Permian and Late Triassic-Early Jurassic events. The Hangayn granitoids are of low mineral potential. Gold mineralization in the area is confined within the Hangayn gold belt and appears to be independent of the intrusions.

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Objective: The aim was to reconstruct the climatic parameters and ice of the Laptev Sea over the last centuries and to identify the causes of their variability. Background: The ice-free water area of the Arctic Ocean has increased considerably during the summer–autumn period in recent decades, which may be attributed to several climatic and oceanographic factors. Methods: The ice-free period duration and mean annual surface air temperature were reconstructed using the transfer function technique to compare hydrometeorological data and the chemical composition of bottom sediments accumulated during the observation period. This approach was based on sub-millimeter scanning of sediments using synchrotron radiation X-ray fluorescence. The results revealed a specific feature of the variations in the mean annual air temperature over the last 400 years in the Laptev Sea region, whereby higher (up to positive) temperature anomalies, were observed during the Little Ice Age. Some discrepancies in the ice coverage and climate fluctuations were observed during the period from the end of the Little Ice Age to the beginning of the period of accelerated ice-cover degradation in the Arctic (1850–1980). These discrepancies can be caused by the beginning of global warming, which have disturbed the natural cyclicality of atmospheric processes, whereas natural variations in ice coverage were more stable. Conclusion: A joint analysis of the reconstructed variations in air temperature and the duration of the ice-free period revealed the influence of atmospheric processes on the ice conditions of the Laptev Sea.

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