Granitoids of the Kozhim massif (Subpolar Urals): U Pb, Lu Hf data

The age (U Pb, SIMS), distribution features of REE, Ti, Hf, Y in zircons of leucogranites of the Kozhim massif (Subpolar Urals) were established, isotope geochemical data (Lu Hf), allowing to establish the isotope geochemical characteristics of rock protoliths were obtained. Two age groups of zircons that differ in age, geochemical (REE distribution), thermal (t crystallization), isotopic (Lu Hf) characteristics, and calculated model ages of protoliths are distinguished. Zircons with an age of 619 Ma crystallized at a temperature of 808 717С, have crustmantle values of the hafniumisotopic composition (+ 0.87 + 1.41), the model age of the protolith TDM2 is 1.33 1.31 Ga. Zircons with an age of 485 Ma were formed at a temperature of 868 742С, have more mantle characteristics of the hafnium isotopic composition (+ 2.50 + 3.42) and the model age of the protolith TDM2 1.15 1.07 Ga. New petrogeochemical, isotope geochemical and geochronological data indicate crystallization of rocks at the Cambrian Ordovician boundary. New petro geochemical, iso tope geochemical and geochronological data indicate the possibility of crystallization of rocks at the Cambrian Ordovician boundary. The obtained time in the evolution of this part of the Subpolar Urals correlates with riftogenic geodynamic conditions (520 480 Ma), under which granites with the characteristics of A granite type were melted. Zircons with older ages are inherited from earlier stages.