Pb-zn Deposit, Yunnan Paul Pecan Floor Mineralization Zoning Pattern Study

The Baoshan block is a Fe, Cu, Au, Ag, Pb, Zn polymetallic metallogenic belt, lies between Nujiang and Lancang jiang fault zones. The Hetaoping as a large Pb-Zn-Cu polymetallic deposit, where in the Baoshan block, and whose ore bodies were stratiform or stratoid, hosted in the group of limestone and skarn of the Hetaoping group and Shachanghe group, on the east of NNE anticline, in upper Cambrian, and, was strictly controlled by nearly SN fault zone and fractured zones of interbedded faults. This paper study of the mineral assemblage, chemical composition, succession of the minerals formed, distribution feature, and, based on the analysis of the geological characteristics and the study of the altered rocks and lithofacies mapping of the V1 ore bodies. The study discussed the mode of the deposit's mineralization zoning, association with the physical chemistry properties of the fluid. Some achievements have been getting as below.1.Based on the generation sequence and interpenetrating relationship of mineral, The author proposed that the mineralization can be divided into skarn stage, hydrothermal sulfide stage and supergene stage. Hydrothermal alteration of the ore district is complex and characterized with multi-stage activities, which is reflected mainly in skarn-hydrothermal sulfide mineralization. six mineralization stages can be distinguished:(Ⅰ) dry skarn stage, (Ⅱ) wet skarn stage, (Ⅲ) skarn-quartz-pyrite-chalcopyrite-sphalerite stage, (Ⅳ) quartz-sphalerite-galena-chalcopyrite stage (Ⅴ) quartz-carbonate-sphalerite-galena stage and (VI) carbonate stage. The stage(III), (Ⅳ) and (Ⅴ) are the main mineraliztion stage of lead-zinc polymetallic2.The deposit has obvious horizontal and vertical alteration banding phenomenon. Horizontal zone has center-symmetrical structure. There are 4 zones form the center of the bodies to the wall rock, skarn-pyrite zone, skarn-Pb-Zn zone, carbonate-Quartz-skarn zone, carbonate-chlorite zone. The zones according to the mineral combination can be divided as, galena-sphalerite zone, sphalerite-galena zone, sphalerite-chalcopyrite-galena zone and pyrite-chalcopyrite-sphalerite-galena zone. The characteristics of the alteration zoning Vertically from deep to the surface is same with the that of horizontal.3.The analysis results shows that the fluid temperature, salinity, pressure, and density appears on the whole is descendant trend, from skarn stage to carbonate phase, according to fluid inclusions petrography, temperature measuring, and inclusion composition. The precipitation temperature of larger amounts sphalerite was 190～210℃. Inclusions composition show that the late phase of of fluid is more reduction than that of the early stage. It shows that the late phase is more reducing than the early stage by inclusion.4.The model of alteration and metallogenesis zoning was established on the basis of the mineral assemblages and mineralization zoning characteristics, combined with the physical and chemical properties of the fluid. It has the universal significance of the model in the Southwest "three rivers" polymetallic ore field, and, it's could help to understand the ore-forming fluid migration and mineralization of the Hetaoping Pb-Zn deposit.5.The genesis of the deposit belongs to a postmagmatic hydrothermal metasomatic type, as vein skarn (similar skarn type) Pb-Zn-Cu polymetallic deposit. It is a multi-stage by lithology, fracture characteristics and development of fluid migration. There is a good prospects to finding the depth mineral resources, and there is contact metasomatic skarn and porphyry mineralization potential, directed against the situation of the ore body.