Age of titanium deposits of the northeastern part of the eastern European Platform: Rb—Sr data

Unique titanium Deposits of Timan: genesis and age issues

“…The age of the Pizhemskoye deposit, as shown by Rb-Sr isotope-geochemical studies, is much older than it is commonly believed, Riphean (685 ± 30 Ma) [23]. The considered model of the Pizhma deposit and the Ichetyu occurrence formation provides for the vertical transportation of huge masses of material like mud volcanoes in a continuous pulsating mode and the filling of negative topographic features of the crystalline basement composed of shale.…”

“…The true age of these deposits is much older, Neoproterozoic (Riphean; PR3mr), which can only be established by isotopic methods. The age of the Pizhemskoye deposit was determined by the Rb-Sr method at 685±30 Ma [23] Ilmenite transforms into leucoxene in shales under supergene conditions This hypothesis has not been proven. Hydrothermal conditions are required for iron removal from ilmenite and impregnation of pores in a sagenite rutile or anatase lattice with quartz with leucoxene formation: the presence of carbon dioxide in the fluid and a relatively high temperature (150-250 С) for the transport of iron bicarbonate and silicic acid (SiO2) in dissolved form [6] Polymorphic transformations of TiO2 occur under supergene conditions: metastable anatase transforms into rutile Researchers of the Timan Riphean shales note that predominantly anatase leucoxene develops after ilmenite in them [8,11,14,16].…”