Geological characteristics and prospecting potential of the Zhaojiaba gold deposit in Longnan city, Gansu province

The Zhaojiaba gold mining area is located in the southern part of Gansu Province, in the eastern segment of the Xinguang-Yangshan Indosinian gold metallogenic belt. Tectonically, it is situated in the Mianlue ophiolitic melange belt, the southern part of the South Qinling Indosinian fold belt, the middle segment of the Wenxian-Kangxian fault, and the northern limb of the Jinkengzi-Zhaojiaba composite anticline. A total of 17 gold orebodies have been delineated in the study area, which occur in the Qiaotou Formation of the Sanhekou Group of the Devonian System. NE-trending and nearly EW-trending fault structural zones serve as the main ore-hosting spaces, and the dikes are mainly quartz diorite porphyrite dikes and quartz veins. The gold deposit in the study area is genetically classified as a meso- to epithermal composite hydrothermal quartz vein-stockwork disseminated tectonic altered rock-type gold deposit, which is hosted in the Devonian carbonaceous-siliceous-argillaceous formation and associated with the Mesozoic deep-derived hypabyssal quartz diorite porphyrite. It is inferred that the deep part of the Zhaojiaba mining area at a depth of 1400 m to 1600 m is an ore-forming enrichment zone.