| Xifanping porphyry copper deposit is located in the middle part of the Sanjiang metallogenic belt,southwestern margin of the Yangzi platform,which belongs to the typical porphyry type copper deposits and locate in Yanyuan,Sichuan Province.It deposit in Sichuan province is a very important and very exploitation of the porphyry copper deposit,but the previous study on the deposit less,so the study of the geochemical characteristics,metallogenic regularity and metallogenic model is of great significance.It is not only an important supplement of polymetallic deposits in Sanjiang metallogenic,provide an important theoretical basis for the prospecting of regional exploration method,and it has a certain significance to determine the regional metallogenic model and metallogenic model of the Sanjiang area of Yanshan period and Himalayan period.In order to investigate the Xifanping porphyry copper deposit geochemical characteristics,metallogenic regularity and metallogenic model,in the southwest China project geological survey work main metallogenic belt of copper iron gold polymetallic ore prospecting model and exploration technology research project(No.1212011220391)of the support system,collect and collate the data of previous the summary and analysis of previous research results,through field geological survey,sample collection and laboratory analysis and testing,using various means of geochemical analysis and the acquisition and processing of the ore,rock,porphyry and sedimentary rock samples,the Xifanping porphyry copper deposit of element geochemistry,petrology,isotope geochemistry and deposit research and U-Pb chronology,discusses the Xifanping porphyry copper deposit geochemistry,ore-forming material source,mineralization time Metallogenic regularity and metallogenic model.The following results were obtained:(1)According to the characteristics of the main elements in the Xifanping copper deposit ore rocks,the geochemical characteristics of various lithology combination investment map,Ailaoshan Jinsha River Himalaya alkali rich intrusive rock belt in Machangjing deposit and Yulong deposit,the Xifanping deposit into the alkali rich intrusive rock belt,and determine the Xifanping deposits(quartz monzonite porphyry)Peraluminous shoshonite rock series.(2)Trace and rare earth elements on samples of Xifanping copper deposits in the analysis of trace element spider diagram shows that the Xifanping porphyry relative enrichment of large ion lithophile elements Rb,Th,U,Hf,relative depletion of high field strength elements of Ta,Nb,Zr,Yb,Ta,and Nb with negative difference often,the REE patterns show strong REE fractionation of right Eu anomaly weak type,combined with the Xifanping deposit magmatite samples SiO2 content from 62.93% to 71.53%.The rock was characteristics of acid rock,and the Sm/Nd value is 0.14~0.16,Eu/Sm value is 0.12~0.20,reflecting the porphyry originated from the crust and mantle contamination.(3)By U-Pb zircon study on four metallogenic porphyry samples,measured the age weighted average values were XF-06(32.18 ± 0.32Ma),XF-22(32.17 ± 0.33Ma),XF-23(32.25 ± 0.43Ma)and XF-31(260.8±3.1Ma),the MSWD value is below 1.9,the formation of age may represent the Xifanping deposit two long quartz porphyry.The age of about 260 Ma in XF-31 samples,showing the Indosinian magmatism formed the Xifanping porphyry copper deposit in the 260.8Ma era,the main ore metallogenic age is about 32.2 Ma,shows that the main metallogenic epoch Xifanping deposit belongs to the Himalayan period,during the interaction of two magma,formed the Xifanping porphyry copper deposit.(4)?Hf of Xifanping magmatite zircon values can be divided into two groups,one group are positive(0.08 ~ 5.43);and another group with negative value epsilon(-4.71 ~-0.21),reflecting the diagenetic process may be involved in crust mantle components.The two stage model age concentrated in 807 ~ 1578 Ma,719 ~ 1077 Ma.The results show that the source rocks of igneous rocks in the study area are mixed with two different source rocks.One kind of magma originates from the crust source separated from the early depleted mantle(TDM2=807 ~ 1578Ma),and the other is the depleted mantle magma(TDM1=719 ~ 1077Ma).(5)The porphyry copper deposit is a complex pluton formed by two magmatic intrusion events.The formation of mining cryptoexplosive breccia pipe of deep magma residual ore gas provides migration channel and precipitation place,many times of rich gas-liquid ore-forming components rise,sedimentary superposition,ore controlling structure and formation of copper ore. |
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