Abstract:The Maoping Pb-Zn deposit, located in Zhaotong City of northeastern Yunnan Province, is a Pb-Zn polymetallic deposit with superlarge-sized potential in Sichuan-Yunnan-Guizhou metallogenic area. The previous studies of its mineralization was weak, and the mineralogical work was especially insufficient. The No. I ore body group occurs in the interformational fault zone of dolomite within upper Devonian Zaige Formation, lying in the west wing of Maomaochang inverted fold. In this paper, based on three-dimensional alternation-lithofacies mapping and petrographic studies of No. I ore body group, the authors established a mineralization-alteration zoning model. The results indicate that the alternation zoning is silicified zone, carbonation + silicification + argillation zone and carbonation zone from the center of ore bodies outwards. Correspondingly, the mineralization zoning changes from massive high grade ore to massive pyrite shell, disseminated-vein-patchy low-grade ore and starry pyrite shell. The mineral assemblage zoning can be divided into Sp+Gn(+Cpy)+Py+Mrc+Apy+Q+Cal assemblage, Py+Gn+Sp+Dol+Fe-Dol+Cal+Q+Ill assemblage, Py+Dol+Fe-Dol+Cal+Q+Sd assemblage and Dol+Cal assemblage. The vertical zoning is not significant, whereas the horizontal zoning is well developed, which is related to the effect of the concentration gradient of vertical physical changes of ore-bearing hydrothermal solution and lithology. Mineralization-alternation can be divided into five stages, i.e., Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴstage. Pyrite shell is the product of early fluid, and banded ore is the product of hydrothermal superposition. The 784 meter level is the ore-forming fluid superimposed striker of Ⅲ stage. Ore-forming fluid temperature of Ⅱ stage is higher than that of Ⅲ stage. The alteration and mineralization zoning model is of great indicating significance for the prospecting of mineral resourcesg and the understanding of the migration, concentration and enrichment of ore-forming fluids.