Sources of Zircons from Clastic Rocks of the Riphean Sequences of the Urals

Resumo

New dates of detrital zircons from sandstones expand the possibilities to interpret their source areas. These interpretations are often constrained by a formal comparison of the geochronological and compositional features of detrital crystals with any very remote complexes. However, there is another situation when the local complexes pretend to be a source of detrital material. Analyses of isotope–geochronological (SHRIMP and TIMS) dates of zircons, the U and Th concentrations, and the comparison of age histograms of primary zircons from Riphean volcanics and rocks of the Taratash complex and detrital zircons from the Vendian (Asha Group) and Lower Riphean (Ai Formation) sandstones have shown that zircon age variations and source areas of zircons are comparable in many aspects. It follows that the geochronological features of primary zircons from the Riphean volcanics and rocks of the Taratash complex as sources of detrital zircons for the Riphean and Vendian sandstones in the Southern Urals are controlled by redeposition processes, though the influence of distant source areas remains possible.