Age of the Dike Complex in the Dunite “Core” of the Kamenushinsky Clinopyroxenite–Dunite Massif, Ural Platinum Belt, Middle Urals

The article presents the first U-Pb (SHRIMP–II) zircon age data on dikes cutting dunite of the Kamenushinsky dunite–clinopyroxenite–gabbroic massif in the Ural Platinum Belt. The dikes are made up of gabbro-pegmatite, hornblendite, and granite, the field relations between which suggest their subsequent intrusion in the dunites. Their geochemical features show that they belong to two different magmatic series. The gabbro–pegmatite is the derivatives of the dunite–clinopyroxenite–gabbro series, while hornblendites are the derivatives of the gabbro series. At the same time, the granite corresponds to anatectic granites developed within the Platinum Belt. U-Pb zircon dating of the gabbro yielded an age of 418.3 ± 4.5 Ma, which can be considered as the upper age limit of the dunite–clinopyroxenite–gabbro series. The age of the hornblendite of 421.0 ± 2.4 Ma is close to the age of the majority of the gabbroic rocks of the Ural Platinum Belt. The U-Pb zircon dating of the granite yielded a relatively young age of 384.9 ± 0.5 Ma. This testifies the continuation of the intrusive magmatic activity within the Ural Platinum Belt after the formation of the youngest volcanic rocks of the Tagil volcanic arc, the gabbro–diorite–granite intrusions of the Auerbakh Complex, and significantly expands the time range of magmatism associated with partial melting of the gabbro protolith directly within the belt.