THE OLDEST VENDIAN (EDIACARAN) FOSSILS OF EURASIA:U–Pb ISOTOPE AGE OF THE BASA FORMATION (ASHA GROUP, SOUTHERN URALS)
The isotopic dating results for the ash tuffs from a section of the Basa formation of the Asha Group of the Vendian (Ediacaran) of the Southern Urals were acquired for the first time using the U–Th–Pb data (SHRIMP II) from accessory zircons. The concordant age was 573.0 ± 2.3 Ma. The dating can be interpreted as the upper age limit of the beginning of the Timan orogeny in the structure of the Southern Urals. Earlier, the rocks of the Upper Basa subformation had been found to contain fossil remains of Kuckaraukia multituberculata, several paleopascichnids belonging to the genera Palaeopascichnus and Orbisiana, and Arumberia banksi were described for the first time. The obtained dating results indicate that the age of these fossils is greater than previously accepted.