| Zhaotong lead-zinc deposit is located in Northeast Yunnan province.It is one of a typical deposit in the region,which has rich germanium content in ore.In this paper,based on ore geological survey of Zhaotong lead-zinc deposit,we draw up a large scale alteration lithofacies map and build the tectonic geochemistry map.Based on the above research,we build the genesis model of "tectonic fluid penetration mineralization".The following conclusions are listed:1)On large scale alteration lithofacies and alteration zonations,we investigate the hydrothermal fluid alterations,include:alteration type,alteration combination,alteration strength,alteration zonation and its relationship with mineral genesis.The result shows that the lithofacies alteration zonation is obvious.From the center to outer of the orebody,it can be divided into near mine zone,transition zone and far mine zone.Calcitization,silicon and coarse-crystalline dolomitization is developed,and shows a positive correlation between the strength of alteration and mineralization.2)Applicants elements quality migration method,we study water-rock interaction of ore-forming fluid driven by the structure.And we also discuss the cause of element migration laws of each alteration lithofacies zone:from grain-refining dolomition zone?far ore zone?transition zone?near zone,there is a close content relationship of ore forming elements of Pb,Zn and Ge,Ag,Cd;early ore-forming fluid have higher content of ore elements,it shows pyritization,iron-dolomitization.That is an important indicator for ore prospecting.In addition,we chose the alteration index(AI)and calculate the AI values of major element to reflect the mineralized intensity.The calculation indicates that there is a stronger of mineralization and has the higher AI values,and vice versa.On the basis of the law of alteration lithofacies zone,the alteration lithofacies zonation model is established.3)Using Tectonic-geochemical fine anatomy technology,combine tectonic-period,we summery ore deposit structures:including evolution of earlier NS-trending structural?nearly NW-trending structural?NE-trending structural?lately NS-trending structural?EW-trending structural zone.The Zhaotong Pb-Zn deposit is respond product of Indosinian orogenic event.We use tectonic-geochemical clustering analysis and R-type factor analysis technology,and obtained composition element combination(taking R=0.45?0.5).According to their geochemical features during diagenetic and metallogenetic processes,they can be classification into three subgroup,?magma type element features' combination(Cr,Ni,Co,V,T1,Nb,Ta,Zr,Hf,U,Th,and ?REE);?high temperature fluid type element features' combination(Li,Rb,Cs,Sc,Be,W,Mo,Sn,and Bi);?Low-middle temperature fluid ore-forming elements features'combination(Pb,Zn,Cu and the associated element such as Ag,and Sb,Hg,Ge,Ga,In,and Cd).It indicates that tectonite suffer ore forming elements from deep source.And it means that tectonic fluid has homogeneous properties,probably participated mineralization.4)Introducing C.B.Grigonia's original Halo's zoning index.We determine the axial zonation of ore bodies' element,as well as front halo,near mineral Halo and tail halo.Superimposed features of I-6 ore body on the spatial show that ore-forming process has multistage.5)Combining with the alteration lithofacies features and tectonic-geochemical anomalies features,geochemical alteration lithofacies-tectonic-geochemical prospecting model is established.Using this model,position of deep prospecting targets at 760 m level is achieved.6)Alteration types,intensity and composition are closely related to mineralization.They are significance for ore prospecting.The combination of tectonic elements analysis can indicate the nature and the source of ore-forming fluid.Ore-forming fluid shows a mixed feature with magmatic water,deterioration water and construction water. |
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