First Data on the Age (U–Pb, SHRIMP-II) and Composition of Zircon from the Unique Yarega Oil–Titanium Deposit, South Timan

Abstract

Isotope–geochemical study of zircon from leucoxene–quartz sandstone of the Yarega deposit in South Timan was conducted for the first time using the Sensitive High-Resolution Ion Microprobe II (SHRIMP), Secondary Ion Mass Spectrometer (SIMS) technique. Two groups of zircons were established. The first group has signs of hydrothermal processing with a high content of Light Rare Earth Elements (LREEs), Y, Ca, Sr, and other nonformula elements. Zircon that had been hydrothermal altered from titanium deposits of Middle Timan (Pizhma and Ichet’yu) is characterized by similar geochemical features. The second group of zircons has signs of magmatic genesis, including enrichment in Heavy Rare Earth Elements (HREEs), a positive Ce-anomaly, and a negative Eu-anomaly. The concordant ages of magmatic zircon grains lie in the range of 1100–2100 Ma with maxima around 1230 and 1540 Ma. The age of the magmatic zircon grains indicates the predominance of detrital material in sandstones, which was received during erosion of the ancient Mesoproterozoic basement, and excludes the participation of clastic material from the Timan–Ural folded region.