The results of U-Pb SHRIMP-II dating of zircon from granitoids of Talitsky molybdenum-bearing massif (eastern slope of the Middle Urals)

Age position and geodynamic conditions of molybdenum metallization and productive granitoids of the Urals formation are very little studied now. This publication contains the results of isotopic dating of granites from Talitsa Cu-Mo-porphyry deposit which should help solve this problem. The timing of formation of the molybdenum-bearing granitoids of Talitsa deposit was determined by applying the U-Pb SHRIMP-II method through zircons (the Center for Isotopic Research of All Russian Geological Research Institute, St.Petersburg). The U-Pb-age has been calculated on 7 (from a total of 11 conduc­ted) measurements with probability of concordanсе 0.996 and MSWD = 0.105 and it is 297.4 ± 2.3 Ma. The results of U-Pb dating are similar to before published Re-Os ages of Talitsa molybdenite deposit: 299.9 ± ± 2.9 Ma and 298.3 ± 1.3 Ma. These data establishes the new unknown before age level of molybdenum metallization. Until recently there has been only data on the Yuzhno-Shameiskoe molybdenum deposit connected with the subalkaline granites of Malyshevo massif which is younger: 277.1 ± 1.1 Ma. According to the received data, the intrusion of investigated granitoids happened practically at the same time as the formation of the wide-spread in the western slope of the Middle Urals intrusive bodies which are accompanied by gold metallization (Verkhisetsky, Shartashsky and others). With such close (practically the same) time of formation the rocks of molybdenum-bearing and gold-bearing massifs significantly differ in petrochemical peculiarities, which probably determines their metallogenetic specialization. Granitoids forming gold-bearing quartz veins on chemical composition are rocks of calc-alkaline series (typical exemple - Shartashskyi massif with Beriozovsk gold deposite). The granitoids productive on of Cu-Mo-porphyry type metallization together with large number of normal alkalinity rocks includes subalkaline rocks such as monzodiorites and quartz monzodiorites.

Урал, гранитоиды, U-Pb SHRIMP-II датирование, Urals, granitoids, U-Pb SHRIMP-II datin

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