Geology, fluid inclusion and H–O–C isotope geochemistry of the Doranasai gold deposit, Chinese Altai: implications for ore genesis

The Central Asian Orogenic Belt experienced a complex subduction accretion–collision history, forming the Irtysh gold belt. The Doranasai deposit is a typical gold deposit in the Irtysh gold belt, but its genesis is still unclear. The Doranasai gold deposit occurs in the east wing of the Aksay syncline. The orebodies are controlled by the NS-trending fault. The main ore types are quartz vein type and altered rock type. Wall rock alteration is represented by albitization, pyritization, sericitization, silicification, chloritization and carbonation. The ore-forming process includes three stages: albite–quartz–pyrite stage, quartz–polymetallic sulfide stage and barren quartz–carbonate stage. The fluid inclusions in the early- and middle-stage quartz are mainly aqueous inclusions and CO 2 –H 2 O inclusions, while only aqueous inclusions are developed in the late-stage quartz. The homogenization temperature of fluid inclusions has evolved from up to 300 °C in the early stage, 180–280 °C in the middle stage to lower than 200 °C in the late-stage, and the salinities have evolved from 4.2–9.6 wt