The age of the basement of Arctic Alaska – Chukotka microplate on the example of the Velitkenay granite-migmatitic dome (NE Russia)

The basement of Arctic Alaska – Chukotka microcontinent (AACHM) is exposed in Velitkenay granite-metamorphic dome of Chukotka. U-Pb (SIMS) geochronological study of the orthogneisses of the basement, paragneisses after Paleozoic rocks and leucogranites of Velitkenay pluton in the central and southwestern parts of this structure is carried out. Neoproterozoic ages of basement orthogneisses (velitkenay complex) and Albian ages of granitoids of Velitkenay pluton are confirmed. The latter concides with the age of orthogneisses migmatization. The youngest zircon clasters from paragneisses within velitkenay complex have Cambrian and Silurian ages, single zircon crystals contain inherited 1.7 and 1.9 Ma cores. The сorrelation of Neoproterozoic orthogneisses of Velitkenay granite-metamorphic dome with similar complexes of the other AACHM regions indicates unity of its basement. It is offered to enter velitkenay metamorphic complex into the legend of Chukotka series of the third-generation geological map sheets.