THE APPLICATION OF DETRITAL ZIRCON DATING IN CONSTRAINING THE DEPOSITIONAL TIME-FRAME OF THE SEDIMENTARY PROTOLITH OF THE DALDYN GROUP QUARTZITE, ANABAR SHIELD, RUSSIA

Quartzites and paragneisses, occurring in the Archean granulite series of the Anabar Shield, Siberian Craton, are described geochemically. The Sm-Nd isotope systematics of the rocks, the U-Pb age (SHRIMP II) and geochemistry of zircons from quartzites and paragneisses were studied. Newly-formed zircons from quartzites display geochemical characteristics of magmatic type produced by rock anatexis upon granulite-facies metamorphism. The Paleoproterozoic age of the latest detrital zircons, 2250 ± 24 Ma, constrains the maximum age of sedimentary rock deposition. Anatectic shells around detrital zircons were formed at ca. 2000 ± 9 Ma ago. The time of deposition of the sedimentary protolith of gneisses and quartzites falls within the age interval of the above mentioned dates and is tentatively accepted as 2.1 Ga. The presence of Paleoproterozoic metasedimentary rocks in the Daldyn Group suggests that the series is tectonically heterogenous and that it contains Paleoproterozoic rock bodies among predominant Archean rock sequences.