Erqis,Armantai,and Kalamaili are three major tectonic belts developed from north to south in the eastern Junggar area of Xinjiang.A large number of orogenic gold deposits have been discovered in the Erqis and Kalamaili belts.Although Armantai tectonic belt has a similar metallogenic background with the north and south tectonic belts,no orogenic gold deposit is reported. Given this problem,we focus on the most important gold deposit in this tectonic belt,the Dunbastau gold deposit. Methods:In this paper,detailed field investigation and microscopic observation are conducted to provide petrography,mineralography,and structural evidences.Results: The Dunbastau gold deposit’s metallogenic process can be divided into three periods:①The sedimentary period characterized by framboidal pyrites;②The diagenesis period characterized by compaction,nodule-formation,and recrystallization of pyrites;③The hydrothermal period characterized by hydrothermal veins production and gold mineralization.The hydrothermal period is further divided into two stages:the ankerite—quartz—pyrite stage accompanied by brittle—ductile deformation and the quartz—albite—calcite stage with the transition from brittle—ductile to brittle deformation.Pyrites can be divided into six generations.Arsenopyrite can be divided into three generations.①Py1 is of sedimentary origin,with particular structures such as framboidal and colloid;②Py2 was formed by diagenesis and distributed stratification consistently. Py2 often show recrystallization or nodule- like shape and other characteristics; ③Hydrothermal Apy1, from subhedral to euhedral,with a grain size of 50~100μm,often paragenesis with gold;④Hydrothermal Apy2 are euhedral,with a grain size of 300~700μm;⑤Hydrothermal Py3 are anhedral to euhedral,with a grain size of 50~150μm,characterized by inclusions and pores internally;⑥Hydrothermal Py4 are subhedral to euhedral,with a grain size of 150~300 μm,characterized by inclusions,few pores,and developing pressure shadow;⑦Hydrothermal Py5 are characterized by high brightness under backscattering and rich in As significantly;⑧Hydrothermal Apy3 are coarse- grained,and euhedral shaped,with few inclusions internally,developed cataclastic texture and pressure shadows; ⑨Hydrothermal Py6 are coarse-grained,from subhedral to euhedral,with few inclusions internally,developed cataclastic texture and pressure shadows.Conclusions:The Dunbastau gold deposit has the “tri-in-one”ore-controlling characteristics:secondary fractures of regional faults,brittle—ductile shear zones,and anticline cores. Among them,the brittle—ductile shear zone with NW—SE strike is the most critical ore-controlling structure.The gold mineralization is significantly later than the host magmatic rock,quartz diorite porphyrite.The geological and geochemical characteristics of the deposit are similar to those typical orogenic gold deposits in the adjacent structural belts.Combined with the nature of ore-forming fluid is medium—low temperature and CO2 rich,it can be concluded that the Dunbastau gold deposit is a typical orogenic gold deposit.Along with the brittle—ductile deformation process,the grain size of pyrites and arsenopyrites increased orderly,the degree of self-shape gradually improved,while the grade of Au gradually decreased.The precipitation of gold mainly occurred in the brittle—ductile deformation process.In contrast,there was no gold mineralization in the brittle deformation process.The fine-grained,disseminated pyrite and arsenopyrite alteration and the ankerite alteration of the main metallogenic stage can be used as indicators for prospecting.