N.I. Gusev, L.Yu. Sergeeva, T.S. Stroev, S.O. Savel’ev, A.G. Sharipov, A.N. Larionov (VSEGEI), S.G. Skublov (IPGG RAS, SPMU)

U­-Pb age, geochemistry and Lu-­Hf systematics of zircon from intrusive traps of the western Tunguska Syneclise, the Siberian Platform

Following zircon ages (U­-Pb method, SHRIMP II) from four trap intrusions was obtained (Ma):
248 ± 2 for Vanga, 241 ± 2 for Yokche, 235 ± 1 for Degali, 230 ± 3 for Perelomnaya. Zircon geochemistry, morphology and structure confirms its magmatic origin. The duration of intrusive trap magmatism is about 20 Myr. The Lu-­Hf isotope system of zircon testifies to depleted mantle source (ε_Hf(T) = +8…+15) and two groups of T_Hf(DM) model ages: Riphean (0.57–0.59 Ga) and Permian (0.26–0.29 Ga). Melting of the Riphean depleted mantle of the Paleo-­Asian Ocean under the influence of the Permian plume is supposed to be a source of trap magmatism.
Keywords: Siberian Platform, trap, zircon, U­-Pb age, SHRIMP II, Lu-­Hf isotope system.