New Isotopic Data on Late Cenozoic Age and Mantle Origin of Gem Zircon and Corundum from Placers of Primorye, Russia

摘要

The paper shows that sapphire (corundum) and hyacinth (zircon) from the Primorye placers have genetic relationships with the Late Cenozoic within-plate basalts of mantle origin. The alternative hypothesis of their derivation from the Early-Middle Cretaceous S-type granites does not fit the evidence presented here. This conclusion is based on the age determinations (less than 15 m.y., zircon SHRIMP and Fission-Track analyses) and oxygen isotope compositions (δ~(18)O SMOW = 4-6.5 vol %) of clastic zircon and corundum from two sapphire districts of Primorye: Marevka, occurring in the Marevka and Kedrovka river basins in the north, and Shkotovo located in the area of upper Arsenievka and Steklyanukha Rivers in the south.