Baddeleyite and zircon from diamond-bearing deposits (D2-3AS) in the Southern Timan

In the Middle Devonian deposits in the south of the Timan, zirconium minerals baddeleyite and zircon have been determined. It is shown that the deposits of the Asyvvozh Formation received minerals from different sources. Baddeleyite contains the following trace elements: HfO2, TiO2 and FeO. The source rocks in which baddeleyite was formed may have been kimberlites: their similarity with baddeleyites from kimberlite bodies is noted in morphology and shape of crystals, chemical composition, edge/center element ratio and Zr/Hf ratio. As a result of transportation, baddeleyite, together with other stable minerals, was transported and accumulated in the deposits of the Asyvvozh Formation. In the studied gravelstones of the Asyvvozh Formation, two types of zircon were found: newly formed zircon overgrowing around baddeleyite and weakly rounded fractured short prismatic grains. The first type of zircon could have been formed when the rock was exposed to silicabearing fluids, which resulted in the reaction replacement of baddeleyite by zircon. Zircon of the second type is characterized by the presence of numerous impurity elements: HfO2, FeO, Al2O3, P2O5, Y2O3, CaO, Sc2O3, Nd2O3. It probably formed as a result of redeposition from the underlying Riphean rocks