ZIRCONS AND THE PROBLEM OF PRECAMBRIAN IN THE MAIN GRANITE BELT OF THE URALS: EVIDENCE FROM THE KOZHUBAEVO METAMORPHIC COMPLEX

Abstract

Metamorphic rocks of the Kozhubaevo Complex (KC) surround the Dzhabyk–Karagai granite massif in the north and northwest. Together with granites, the metamorphic rocks belong to the Ural–Tobol’sk anticlinorium of the East Uralian Anticlinorium. The issue of the KC age is a characteristic problem of all similar gneissic complexes in the Urals, since geological data suggest both Paleozoic and Precambrian ages for the gneisses, while geochronological data are limited by only a few K–Ar datings within 250–350 Ma.