The ⁴⁰Ar–³⁹Ar Age of Folding in the Sedimentary Complexes of Chukotka and Wrangel Island (Northeastern Russia)

The ⁴⁰Ar–³⁹Ar isotope dating of newly formed micas and chlorites from thrust zones made it possible to establish that they were formed in the Tithonian (150 Ma). Sedimentary rocks from the Devonian to Triassic were involved in thrusts. An older stage of deformations of 257 Ma was established in the Silurian rocks composing the Dream-Head Mountains of Wrangel Island. This age corresponds to the Late Permian stratigraphic interval and indicates the existence of deformations after the Ellesmerian orogeny in the Early Carboniferous. The formation of thrusts was accompanied by the heating of sedimentary sequences up to temperatures of 250–380°C, while the temperature regime in the thrust zone almost did not change. The temperature difference between the thrust zone and under the thrust is not more than 20°C.