| Lishan Pb-Zn deposit is located in Tianbaoshan mining area,Yanbian,Eastern Jilin Province,and its geotectonic location is on the west side of Yanbian excellent geosyncline fold belt on the eastern margin of the North China plate,and the north side of Yanji sag,which is the combination of the Binxi Pacific tectonic metallogenic domain and the Paleo-Asian tectonic metallogenic domain.There are four main mineralization types in Tianbaoshan mining area: sedimentary-hydrothermal reformation type,contact metasomatic type(skarn type),hydrothermal vein type and porphyry type.It has been found that deposites like Lishan,Houshan,Xinxing,Dongfeng Nanshan and Dongfeng Beishan are multi-genesis,multi-type,multi-source,multi-stage and multi-species ore field.In this paper,the metallogenic geological characteristics of Lishan skarn Pb-Zn deposit are systematically analyzed and summarized.It is considered that the ore bodies occur in the contact zone between the Late Triassic diorite,granodiorite and marble of the upper Carboniferous Tianbaoshan formation in the deep Lishan lead-zinc deposit and in the skarn body nearby.Two groups of ore-bearing skarn ore belts were controlled by the NW-trending and NE-trending structures.Ore bodies are vein,lenticular and lenticular,distributed side by side in parallel with each other,with partial shrinkage and expansion.The main metal sulfides in ore mineral composition are sphalerite.The other metal minerals with relatively low content are hematite,zinc-iron spinel,pyrite,siderite,galena,lead-antimony sulfate,galena,chalcopyrite and so on.Non-metallic minerals are mainly quartz,carbonate,feldspar,other amphiboles,pyroxene,diopside,garnet,epidote,mica,clay minerals,barite,celestite and a small amount of other minerals.The natural type of ore can be divided into zinc sulfide skarn ore.The wall rock alteration of the orebody is mainly banded skarn,and the main altered minerals are garnet,diopside and epidote.This paper comprehensively collects the research data of lithogeochemistry,fluid inclusions,isotope tracing and dating of Lishan lead-zinc deposit.Comparing Lishan lead-zinc deposit with the new lead-zinc deposit and Dongfeng molybdenum deposit in the adjacent area,the genesis of Lishan deposit is comprehensively studied and analyzed.It is considered that the Tianbaoshan mining area has experienced three metallogenic types: Lishan lead-zinc deposit of Hercynian period in Lishan,Xinxing lead-zinc deposit and Dongfeng Beishan molybdenum deposit in Yanshanian period.Fluid inclusions and isotope geochemical studies indicate that the ore-forming fluids of Lishan lead-zinc deposit originate from high temperature and high salinity-system of magmatic water,which is closely related to cooling and crystallization differentiation of Hercynian granodiorite magma.In the later stage,the influx of meteoric water,but many metallogenic elements still come from magmatic fluid system,although some lead comes from marble of Shanxiuling Group.Based on the new geological theory and the practice of mine,the metallogenic model of skarn type lead-zinc deposit is established,and the metallogenic prediction of deep mine is made.It is believed that the NW and NE trending structures are widely developed in this area,and they are characterized by multi-stage activities.Especially near the inner and outer contact zones of deep granodiorite and diorite,the multi-stage intrusion of magma resulted in the occurrence of multi-stage structures,which created a good space and place for mineral precipitation and made ore-bearing solution sulfide in dense massive form with copper,lead and zinc.Mineralization is formed by fissure filling in the form of matter,veinlet sulfide,zinc-bearing skarn and disseminated skarn-like marble.At last,92 orebodies were found below the deep-92 m elevation controlled by deep tunnel and drilling engineering,which confirmed the correctness of the metallogenic model and deep prediction from this paper. |
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