U–Pb (SHRIMP) Zircon Age of Granitoid Pebbles from the Kukkarauk Conglomerates of the Vendian Asha Group (Alatau Anticlinorium, Southern Urals)

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Abstraсt

The lack of reliable geochronological data for the Vendian deposits of the Urals and other regions is one reason why there is still uncertainty in the age estimates of the Vendian lower boundary. According to the resolution of the Interdepartmental Stratigraphic Committee, it is distinguished at the level of 600 ± 10 Ma. Based on zircons from granitoid pebbles from deposits of the Kukkarauk Formation in the Vendian reference sections of the Alatau anticlinorium, the concordant U–Pb SHRIMP age of 713.6 ± 6.1 Ma was obtained. In fact, this is the only reliable age at present that can be used as a reference for rocks of the provenance area of the Vendian water basin in the Southern Urals. Moreover, this is evidence that this provenance area in the Vendian included granitoids, similar to granites of the Mazara and Barangulovo massifs, located in the northern part of the Uraltau Zone of the Southern Urals, to the east of the area of the Vendian sedimentation.