The Geochemical Characteristics And Genesis Of The Shuitoushan Pb-Zn Deposit,Zhenkang Town,Wester Yunnan

Shuitoushan Pb-Zn deposit is a lowtemperature type deposit,which was one of the significant results from the Zhenkang Pb-Zn-Fe-Cu polymetallic ore concentration area in Baoshan block,Western Yunnan.The ore bodies of this deposit occured as either stratiform-like or lentiform within the marbleization-limestone of the Upper Cambrian Baoshan Formation,and was controlled by NEE trending fault.The ore types are mainly disseminated,massive,brecciated and reticular-veined etc.,with sphalerite and galena as main and chalcopyrite and pyrite as occasionally ore minerals;dolomite,chlorite,calcite,quartz and sericite as dominant gangue minerals.Based on the detailed study of the geological features of the deposit,combined with trace rare earth elements,C,H,O,S and Pb isotopic compositions,this paper was focused on the sources of metallogenic fluids and materials,and compared with the adjacent Luziyuan super-large Pb-Zn-Fe-Cu polymetallic deposit,which provides a theoretical basis for guiding the deep metallogenic prognosis in the mining area.The main understandings are obtained as follows:(1)The trace elements data of single minerals,ore,wallrock and their Y/Ho ratios from the Shuitoushan ore deposit show that the sources of metallogenic materials is related to the deep magmatic activity;The rare earth elements distribution pattern of single minerals,ore and wallrock is similar,and is very consistent with that of the single minerals from Luziyuan ore deposit,and is good agreement with region granite(Kejie and Zhibenshan)of the Baoshan block,it is also indicated that the rare earth elements of metallogenic fluids from the Shuitoushan ore deposit is mainly derived from the deep magmatic hydrothermal fluids.(2)The values of 8D and ?18OH2O of quartz in the deposit range from-101.1‰ to-93.3‰ with average of-96.85‰(n=4)and from 3.37‰ to 3.77‰ with average of 3.57‰(n=4)respectively,imply that metallogenic fluids is magmatic water as dominant in early period,while meteoric water is increased gradually in later period.(3)C and O isotopic compositions of calcite(Phase ?:?13CV-PDB values range from-0.6‰ to 0.5‰ with average of-0.05‰,and ?18OV-SMOW values vary from 11.4‰ to 12‰ with average of 11.7‰,n=2;The values of ?13CV-PDB and ?18OV-SMOW of calcite vary from-6.5‰ to-5‰ with average of-5.7‰ and from 9.8‰o to 10.5‰with average of 10.15‰ respectively,n=2)in the Shuitoushan ore deposit show that metallogenic fluids is the deep magmatic fluids as dominated,which may be mixed with meteoric water in later period.(4)834S values of the sulfides are all positive,and vary from 4.1‰ to 12.2‰with average of 8.23‰(n=10).834S values of phase ?(n=2)and phase ?(n=1)vary from 12‰ to 12.2‰,and approach the ?34S values(8.9‰ to 12‰)of the adjacent Luziyuan deposit.Phase ? is the main stage of this deposit related to sphalerite and galena(?34S values are mainly concentrated between 4.1‰ to 6.2‰),The ?34SAverage can be used to represent approximately the ?34S?S of metallogenic hydrotherm i.e.?34S?S??4SAverage = 6.56‰(n=7).834S values of sphalerite and galena are partially overlapped,while they have the distribution characteristics of ?34Ssphaterite>?34SGalena,and ?34SDark-brown>?34SBrown>?34Sight-brown between the different colors of sphalerite on the whole,it is showed that S isotope fractionation has reached equilibrium,which S isotopic compositions are relatively stable,and that The Shuitoushan ore deposit has the characteristics of the Deep magma in origin.(5)Pb isotope analysis of metal sulfides in this deposit is made,and the results show that it is very concentrated.The points are mainly distributed above the Upper Crust evolution line,indicate that their Pb are primarily derived from the Upper Crust materials related to magmatism.Combined with ore geology,trace.rare earth elements and C,H,0,S,Pb isotopic compositions,this paper argues that the Deep magmatic hydrotherm in the mining area is the most important sources of metallogenic fluids in the Shuitoushan ore deposit,metallogenic minerals are of diverse sources,and this deposit is characterized by low temperature and epigenetic mineralization,speculate that the formation of this deposit is related to magmatic hydrothermal ism of late Yanshan epoch.