Ancient mantle lithosphere beneath the Khanka massif in the Russian Far East: insitu Re-Os evidence

The Os-isotope compositions of sulphides in mantle xenoliths hosted by Late Miocene alkali basalts from the Sviyaginsky volcano, Russian Far East, reveal the presence of Archaean-Proterozoic subcontinental lithospheric mantle beneath the Khanka massif. Their T-MA and T-RD model ages reveal similar peaks at 1.1 and 0.8Ga suggesting later thermotectonic events in the subcontinental lithospheric mantle, whereas T-RD model ages range back to 2.8 +/- 0.5 (2 sigma) Ga. The events recognized in the subcontinental lithospheric mantle are consistent with those recorded in the crust of the Khanka massif. The sulphide Os-isotope data show that the subcontinental lithospheric mantle beneath the Khanka massif had formed at least by the Mesoproterozoic, and was subsequently metasomatized by juvenile crustal-growth events related to the evolution of the Altaids. The Khanka massif is further proposed to have tectonic affinity to the Siberia Craton and should originate from it accordingly.