Hafnium isotope composition of zircon from the platinum-bearing Feklistov massif (Shantar Archipelago, Sea of Okhotsk, Russia)

Abstract

Object. This study firstly evaluates Hf-isotope characteristics of zircons from wehrlite of the platinum-bearing Feklistov massif, which is closely associated with platinum coastal placer deposits. Materials and methods. In-situ Hf-isotope data were collected on the dated spots within zircon grains using a New Wave LUV213 laser-ablation microprobe attached to a Nu plasma MC-ICP-MS. Resuts. Significant variations of 176 Hf/ 177 Hf i (0.28241-0.28312) and eHf(t) (from -4.8 ± 1.1 to 20.3 ± 0.6) in Paleozoic zircons indicates interaction of a ‘juvenile’ mantle source (eHf(t) ≈ 15) with distinct magma sour­ces, possibly equivalent to a subcontinental lithospheric mantle and/or a continental crust (eHf(t) от -5 до +5). Proterozoic and Late Archean zircons from the Feklistov massif are characterized by less pronounced 176 Hf/ 177 Hf i (0.28107-0.28224) and eHf(t) (from -4.8 ± 0.4 to 8.1 ± 0.6). Conclusion . Hf-isotope features for majority of Precambrian zircons from the Feklistov massif (eHf(t) from -3.8 ± 0.5 to +2 ± 0.5) are consistent with their xenogenic nature and inheritance from basement rocks of the Siberian Craton.