Zirconology of serpentinites from Nyashevo massif (Southern Urals)

摘要

Zircons in serpentinites from Nyashevo massif of the Ilmenogorskii complex were dated for the first time by means of the SHRIMP technique. The maximum date of 1892 +/- 23 Ma for the zircons accounts for the minimum age of their mantle substrate probably constituting the restite residue. The date is comparable to those for metamorphic rocks of the Selyankino group, as well as of fenite-sand amphibolites of the Ilmenogorskii complex. The Upper Ordovician age limit of 443 +/- 12 Ma is adequate for formation of the massif and conforms to the age of the Buldym massif and miaskites. The Early Permian dates of zircons (275.8 +/- 2.1 Ma) represent late shear processes in the Ilmenogorskii complex.