Abstract:Yanjiao Pb-Zn deposit is located in the Mesozoic-Cenozoic depression basin of Simao. The ore bodies are mainly hosted in the lower Cretaceous Jingxing Formation strata and sporadic small orebodies are hosted in the He Pingxiang Formation strata. The ore bodies are mainly veined and lenticular and controlled by faults. The ore-bearing lithology is yellowish-white, gray-white, yellowish-green powder-fine-grained, medium-grained quartz sandstone and lithic quartz sandstone. The metallic minerals in the ore are sphalerite, galena, pyrite, chalcopyrite and arsenopyrite. The main surrounding rock alteration is pyritization and calcification. The regional geochemical and petrochemical characteristics show that the Pb and Zn contents in the red beds (T-E) of the basin are more abundant than those in the crustal Clark values, and the red beds in the basin may provide material sources for the Pb-Zn mineralization in this area. The metallogenic process is that in the early Cretaceous, accompanied by the sedimentation of clastic rocks, lead and zinc precipitated and enriched among the rock mineral grains, accompanied by the occurrence, development and deepening of the Himalayan tectonic movement, the deep hot brine and tectonic hydrothermal fluid migrated upward along the deep and large faults driven by the stress, and reacted with the rock beds. The Pb, Zn and other minerals in the strata are continuously extracted to form ore-forming hydrothermal fluid, which is mainly filled along faults and joints to form vein-like orebodies with the same occurrence. Some ore fluids are superimposed on the low-grade orebodies formed in the early stage to enrich them. The genetic type of deposit is sedimentary hydrothermal alteration deposit.