| The Yunnan Pulang Copper Deposit is located on the west side of the Ganzi-Litang junction,the eastern margin of the Dege-Zhongdian block,and the southern section of the Yidun-Zhongdian Island arc in the Indosinian period.It is currently the largest underground metal deposit in our country.It is also the largest super-large porphyry copper deposit in the Zhongdian ore concentration area,and its depositralization is complex and diverse and highly representative.This paper takes the first mining area of Pulang Copper Deposit as the research object.Based on the in-depth study of the geological characteristics,wall rock alteration,and depositralization characteristics of the mining area,according to the theory of mass balance,the element activities of the various alteration stages in the depositralization process of the mining area are analyzed.The characteristics,the law of element mass migration,the deep abnormal structure,and the selection of depositralization indicator elements have been studied,and the following main understandings have been obtained:(1)Pulang Copper Deposit is a typical super-large porphyry deposit in the area.The alteration zone of rock mass in the first mining area has the characteristics of typical porphyry deposit alteration zone in both the plane and the vertical direction: The potassium silicification zone?the pyrite-sericidization zone?the green rock formation zone is formed successively outside;and the same as the alteration zoning,the depositralization intensity also has obvious zoning characteristics with the process of hydrothermal alteration,that is to say Industrial grade Cu and Mo ore bodies are mainly concentrated in the potassium silicate zone and the pyrite-sericite zone,which is consistent with previous research conclusions..(2)Rock geochemical research shows that the alteration zone of Pulang Copper Deposit is generally rich in K2 O and Ca O,with high loss on ignition,and poor in Mg O,Na2 O,Al2O3,TFe2O3,Mn O,and Ti O2;The rocks in the metamorphic zone are generally rich in ore-forming elements such as Cu,Sb,Mo,Zn,and Ag,and rockforming elements such as Rb and Ba;in different alteration zones,the distribution of elements changes to a certain extent,from the potassium silicate zone to the blue rock The content of Cu,Mo,As,Ag,Sb,U,Pb and other elements in the chemical zone has gradually decreased,and the elements such as W,Rb,Sr are the most abundant in the pyrite-sericite chemical zone.Tectonic environment research shows that the rock mass in the first mining area of the Pulang copper deposit belongs to the typical continental arc I-type granite formed by partial melting of the oceanic crust,which provides an important source of ore-forming material for the Cu depositralization of the Pulang copper deposit.(3)The study of the law of element migration shows that in the process of depositralization alteration,the degree of migration of major elements is significantly greater than the degree of migration,and the major elements brought in are Ca O,P2O5,Si O2,K2 O,TFe2O3,Ti O2,Mn O,etc.;the main element brought out is Na2O;the migration degree of trace elements is greater than the migration degree,and the migration is mainly in the potassium silicate stage and the pyrite-sericite stage,and is mainly Copper-philic elements(Pb,Zn,Cu,Bi,Ag)and tungsten-molybdenum elements(Mo,W)are most significantly enriched in the potassium silicate stage and the pyrite-sericinization stage;Ag,The elements Li,S,Pb,Mo,Cu,W,Zn,As,Cs,Ba,and Bi are enriched and migrated in each alteration stage;while the rare elements(Hf,Sr,Ga,Be,Nb)It appears as the whole process of leaching and migration,of which Ga and Sr have the most obvious depletion characteristics;Y,V,U,Th,and Sc are carried in a large amount in the pyrite-sericidization stage,and in the Qingpan lithification stage.In the potassium silicate stage,it is relatively stable;the total amount of rare earth remains relatively stable,but each element has different degrees of activation and migration characteristics,and the activity of LREE elements is significantly greater than HREE;and for different alterations In terms of stages,the highest migration rate of rare earth elements is the pyrite-sericidization stage,followed by the potassium silicate stage;the overall activity state of the blue rockization stage is the leaching migration.(4)Deep anomaly research indicates that within the current control range of deep boreholes,the geochemical environment of negative Na2 O anomalies,positive anomalies of S element,and positive anomalies of main ore-forming elements Cu and Mo are still maintained,and no See the lower limit of anomaly,that is,there is a prospect for deep Cu and Mo prospecting;while the associated elements such as Ag and Zn are still abnormal within the current drilling control range,but the abnormal area is relatively small,and the degree of correspondence with known mining bodies is relatively small.Low,low abnormality and low background values of Ag and Zn in the mining area,so prospecting prospects are not great. |
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