| Yunnan Pulang large porphyry copper deposit is located in the middle of the southwest Sanjiang metallogenic belt,formed in the island arc structure environment,is the Indosinian Ganzi-Litang oceanic crust westward subduction in the Gezan-Zhongdian micro-block,And lead to large-scale magmatic-mineralization results.Based on the surface and tunnel geological survey,this paper takes the Yunnan Pulang deposit as the research object,and from the outcrop scale,the core specimen scale and the microscopic scale,the first mining area and the external hydrothermal The alteration type,the veins system and its relationship with the mineralization,and the similarities and differences between the hydrothermal alteration and the phylogenetic characteristics of the first mining area,the northern section of the mining area and the eastern part are analyzed.Comparison of Typical Porphyry Deposits at Home and Abroad.The authors also analyzed the external prospecting potential from the alteration-vein-mineralization combination characteristics,combined with the newly obtained magnetic anomalies,abnormalities of excitation,radioactive anomalies and geochemical anomalies.This article obtains the following main understanding.1)The geological survey of the mining area and the comprehensive analysis of the data show that the magma activity span in the Pulang mining area is large and the magmatic-Yanshan-Himalayan magma evolution process is experienced.Among them,the acid porphyry body in the Indosinian period is especially developed,which constitutes the main body of the magmatic rock in the mining area,and has close relationship with the mineralization..Through the actual investigation of the first mining area ? rock mass,the northern part of the mining area ? rock mass and the northern part of the ? rock mass,it is confirmed that they are multi-stage magmatic intrusion formation of complex porphyry body,mainly by the early quartz diorite porphyrite and late of the quartz double porphyry or granite diorite porphyry composition.2)This paper focuses on the systematic observation of the alteration types and alteration zonation phenomena in the rock mass,the northern II rock mass and the northern part ? rock mass and its surrounding rock in the first mining area of the Pulang mining area.The results show that the Pulang mining area The developmental degree of alteration types related to porphyry hydrothermal fluids in different sections(ore section)is different,but they all have typical alteration zonation characteristics of porphyry deposits.From the center to the periphery followed by the development of potassium silicate alteration zoning,the Yellowstone Silkite petrochemical alteration zonal zone,the Qingpan petrochemical alteration zonation zone and the keratotic zone.According with Lowell and Guilber(1970),the authors proposed the "two long rock" alteration zoning model.The Prandtl deposit is similar to the typical porphyry copper deposit at home and abroad,However,there are some differences:the carbonate and algae alteration are mainly superimposed on other alteration zonation zones without obvious independent alteration zone;The petrochemistry and kaolinite are extensively developed,and the sericite zone is also often characterized by copper mineralization,forming a certain amount of copper ore body;external rock often rock formation,which are the Pulang mining area Features.3)The ore body in the Pulang mining area is mainly produced in the potassium silicate zone and the silicic acid zone,and the main ore-bearing rocks are quartz monzonite porphyry.Mineralization,like hydrothermal alteration,also has a significant zonation:the strong potassium silicate zone is largely weaker in the alteration center;the medium potassium silicate alteration zone is often developed with high grade Cu mineralization;weak potassium silicate alteration zone is often silicified and pyrite mineralization superposition,although the brass mineralization has weakened,but can still meet the industrial grade requirements,often forming a thick ore body;Medium silicite-weak silicic acid zone,mainly to pyrite mineralization,brass mineralization was significantly weakened,it is difficult to form the economic value of the ore body.The precipitation of chalcopyrite begins in the stage of potassium silicate,and the silicification stage is the main precipitation period of metal sulfide.Therefore,the potassium silicate zone and the sericite zone can be used as one of the important prospecting signs of the Pulang mining area.4)On the basis of observing the characteristics of more than 1000 veins in 18 drilling holes in the six hatching lines of the Pulang mining area,the mineral assemblage,the interspersed relationship,the distribution location,the rock type and the corresponding alteration zone The veins in the mining area are classified into five categories,such as the pre-mineralization vein,the pre-mineralization vein,the ore-forming period B-veins,the mineralization-later ED veins and the mineralization D-veins,and subdivided into 23 Small class.The characteristics of the veins system in the Pulang mining area are similar to those of the majority of porphyry deposits in China and abroad,especially with the Tibetan multi-long deposits,but also have many special features:no high temperature veins The phenomenon of metal sulfide in the veins is mainly composed of chalcopyrite,pyrrhotite and pyrite,and the minerals such as primary magnetite,hematite and anhydrite,which characterize high oxygen fugacity,are not(or Rarely)development,contrary to the formation of mineralization and late mineralization are developing a large number of pyrrhotite.This indicates that the ore-forming fluid of the ore deposit is reductive.5)The results show that the alteration-vein-mineralization has certain significance to the denudation degree of the ore deposit:the vertical borehole core of the Pulang deposit shows that the section is from the top to the bottom,The diagenetic characteristics of Au-Ag-Pb-Zn-Cu,the D-type veins,and the D-type veins developed in order from the surface to the deep,Veins,B-type veins,EB-type and A-type veins.These evidences indicate that the outer extent of the Pulang deposit is low and the mineralization-alteration zone is more intact.6)According to the spatial distribution,type combination and the relationship with different porphyry bodies,the author discusses the hydrothermal-alteration mineralization center of the Pulang mining area,and considers that the first mining area is the most The main metallogenic centers,the eastern and outer parts of the periphery should be the epitaxial part of the first mining area,and the northern part of the mine and the northern part of the periphery may be another secondary hydrothermal-alteration-mineralization center.7)Above all,prospecting potential of Pulang mining area can be summarized as follows:the first mining area of deep mining is still the main goal of mine ore prospecting;deep mining area north should have a certain potential for prospecting;peripheral North lead-zinc poly-metallic ore finding has the potential;outside the south is looking for "structure altered rock type" gold deposit potential,at the same time should also pay attention to the clues for prospecting skarn deposit;the eastern peripheral plate is thick-back,so the deep prospecting potential is small. |
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