Boundary between the Lower and Middle Carboniferous in the Eastern Urals: New isotope–geochronological data

Abstract

The U–Pb age of the boundary between the Lower and Middle Carboniferous has been determined on zircons separated from a volcanic tuff layer within a limestone unit near the roof of the Serpukhovian Stage in an occurrence at the right bank of the Iset’ River. The zircons have been dated using SIMS SHRIMP-II at 320 ± 3 Ma. The result agrees well with the accepted age of the boundary between the Serpukhovian and Bashkirian ages (323.2 ± 0.4 Ma, [1]).