The local geology is characterized by relatively simple stratigraphy but intense tectonic and magmatic activity, which has created favorable conditions for mineralization. Structural features are dominated by five major NNE-NE trending fault systems, with the F4 fault being the primary ore-controlling structure, controlling the development of the No. IV main orebody. Located centrally within the mining area, F4 has a surface exposure of >1200 m long, striking about 15° with a SE dip (42–85° dip angle).
Fifteen gold orebodies have been delineated in the Moshan gold deposit, among which one main orebody (IV-1) and three secondary orebodies (IV-2, IV-3, and III-2) have economic significance, with a cumulative proven gold metal reserve of 15 tons. The gold resource of the IV-1 main orebody accounts for 67.07% of the total resource of the deposit. The orebody is vein-shaped, with local swelling and contraction phenomena. Lithology is mainly pyrite-sericitized granitic cataclasite intercalated with quartz veins, and the occurrence is consistent with the F4 fault, with a general strike of 15°. The length delineated by drilling data is 570 m. The thickness of the orebody ranges from 0.24 to 6.02 m, with an average thickness of 1.84 m, and the gold grade ranges from 1.03 to 83.29 ppm, with an average grade of 10.23 ppm.
Three metallogenic stages are defined. ① Auriferous quartz-coarse-grained pyrite stage (Stage I), with the mineral assemblage including quartz, pyrite, native gold, and sericite. At this stage, quartz and pyrite form a symbiotic edge structure. Pyrite is well-crystallized, generally coarse-grained, mostly euhedral, massive, and occasionally galena and sphalerite fill along fractures, which is a secondary metallogenic stage of gold. ② Auriferous quartz–pyrite–polymetallic sulfide stage (Stage II), the mineral assemblage includes pyrite, marcasite, galena, sphalerite, and quartz, which is the formation stage of polymetallic sulfides and the main metallogenic stage of gold. ③ Pyrite–carbonate stage (Stage III), the mineral assemblage includes calcite, pyrite, siderite, and quartz. No gold precipitation occurred at this stage. Calcite occurs as subhedral granular forms, quartz as subhedral crystalline granular forms, and siderite as veinlet-like, which is the late metallogenic stage.
The Moshan gold deposit formed in a mesothermal-epithermal depth environment. Integrating the ore-controlling factors and metallogenic mechanisms, the formation of this deposit is jointly controlled by tectonic and magmatic-hydrothermal activities, classifying it genetically as a tectonic-magmatic-hydrothermal composite gold deposit.

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