ГРАНИТОИДНЫЙ МАГМАТИЗМ СЕВЕРА УРАЛА: U-Pb ВОЗРАСТ, ЭВОЛЮЦИЯ, ИСТОЧНИКИ

This work presents the summarization of U–Pb (SIMS, TIMS) zircon dates and petrogeochemical signatures of granitoids of the north of the Urals (Polar, Subpolar, and Northern Urals) obtained over the last decade. Granitе melts were formed from melting of different substrates, highly heterogeneous in composition and age, at all geodynamic stages distinguished in the studied area. Preuralides include island arc–accretionary (735–720 Ma, 670 Ma), collisional (650–520 Ma), and rift-related (520–480 Ma) granitoids. Uralides includes primitive island-arc granitoids (460–429 Ma), mature island-arc granitoids (412–368 Ma), early collisional (360–316 Ma) and late collisional (277–249 Ma) granitoids. As a result, the general trend of variations of oxygen (δ 18 O Zrn , ‰), neodymium (eNd (t)wr ), and hafnium (eHf (t)Zrn ) isotope compositions identified in time. Mantle isotope compositions (δ 18 O Zrn (+5.6), eNd (t)wr (+1.7), eHf (t)Zrn (+8.7...+10.6)), common for island arc granitoids (Preuralides) are changed by crustal–mantle ones (δ 18 O Zrn (+7.2...+8.5), eNd (t)wr (–4.8...+1.8), eHf (t)Zrn (+2.1 to +13)), typical of collisional granites. According to this, the crustal matter played a significant role during the formation of the latter. The crustal-mantle isotope compositions are changed by the mantle ones, characteristic of rift-related (δ 18 O Zrn (+4.7...+7), eNd (t)wr (+0.7...+5.6), eHf (t)Zrn (–2.04...+12.5)) and island-arc (Uralides; δ 18 O Zrn (+4.2...+5.7), eNd (t)wr (+4.1...+7.4), eHf (t)Zrn (+12...+15.2)) granitoids.