The age of the granitoids in the Dolanasayi gold ore district in Xinjiang and its constraints on gold mineralization

Abstract: Medium- to large-sized gold deposits, such as Dolanasayi, Saidu and Zhelande, are distributed along the southwestern margin of the Altay orogenic belt. In recent years, exploration work has let to the discovery of the Vodok deposit and some other small-sized gold deposits in this belt. These gold deposits mainly occur in the mylonitic quartz diorite. The quartz diorites in the Vodok and the Dolanasayi gold deposits share similar geochemical features, and they are genetically related to a common magmatic activity. On the other hand, the Sarewuzeng tonalite outcropped between the the Vodok and the Dolanasayi gold deposits show very different petrography and structure. LA-ICP-MS U-Pb zircon ages reveal that the gold-bearing quartz diorite in the Vodok deposit and Sarewuzeng tonalite crystallized at (299.4±4.1) Ma and (317.7±1.5) Ma, respectively, indicating that the quartz diorite and the tonalite were formed at post-orogenic and post-collision settings individually. The age of gold-bearing quartz diorite in the Vodok deposit constrains the lower limit of the formation age of the Dolanasayi gold deposit. In combination with previous studies and the age obtained in this study, the mineralization of the Vodok and the Dolanasayi gold deposits most probably took place at about 290 Ma. The Sarewuzeng tonalite was emplaced earlier than the gold mineralization and was of no significant relationship with gold mineralization in this area.