THE POLYGENOUS-POLYCHRONOUS NATURE OF ZIRCONS AND THE PROBLEM OF THE AGE OF THE BARANGULOV GABBRO-GRANITE COMPLEX

Abstract

The first precision U–Pb (SIMS SHRIMP II) zircon datings of gabbros (728 ± 8 Ma) and granites (723 ± 10 Ma) have been reported for the Barangulov gabbro–granite complex located in the northern Uraltau zone of the southern Urals. The temporal evolution of the magma chamber has been traced based on zircons. The available data suggest that gabbros and granites of the study region are dated at 725 ± 5 Ma. Based on these data, metasedimentary rocks of the Mazarin and Arvyak formations, which host the Barangulov gabbro–granite complex, are older than 725 Ma. This estimate supports the correlation of metamorphic rocks of the Mazarin and Arvyak formations of the northern Uraltau zone with rocks of the Karatau Group in Riphean type sections of the Bashkirian anticlinorium, southern Urals.