Tectonic Structure and Geodynamic Settings of Neoproterozoic Granitoid Magmatism of the Eastern Arctic

The correlation of Neoproterozoic granitoid magmatism of the New Siberian Islands, Wrangel Island, Chukotka, the Chukchi Borderland, and Northern Alaska indicates integrity of the Arctic Alaska–Chukotka microplate basement and the formation of the continental crust during the Timanian (Baikalian) orogeny. The age of inherited cores of zircons and the Nd model age point out the participation of the Meso- and, less frequently, Paleoproterozoic crust in the formation of the epi-Grenville Arctida continent. In the modern structure, Timanides extended from the Timan Range through the Polar Urals and Taimyr to Chukotka and Northern Alaska, framing the margins of the Baltics, Siberia, and North America continents. It is suggested that the geodynamic setting of Neoproterozoic granitoids for most of the microplate is supra-subduction continental margin, less frequently, rift-related at the late stages of the Timanian orogeny. The origin of the Grenville and Neoproterozoic–Timanian population of detrital and inherited zircons is explained by local provenance areas.