Geochemistry Of Fulechang Lead-Zinc Ore Deposits,Northeast Yunnan Provinces

Fulechang Large Lead-zinc Deposit is located at the southern section of the the Sichuan-Yunnan-Guizhou polymetallic ore concentration area(or Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province)in the southwest China.Its ore bodies are of layered,lenticular occurence in the dolomite inter-layer fracture zone of of the Middle Permian Maokou Group.The deposit contains the amount of Pb and Zn metal of more than 2 million tons with the average grade of Pb and Zn of more than 15.6%.The ores are rich in a variety of dispersed elements such as Cd,Se,Ge and Ga,etc.In particular,in the sphalerite ores the average content of Cd is 16,183ppm,which is the highest content in the lead-zinc deposits ever found in China up to now.A lead-zinc deposit accompanying four kinds of dispersed elements with a large scale can be known as a rare one in all the lead-zinc deposits in the world.Systematic studies on regional geological setting,deposit geology,elemental geochemistry,isotope geochemistry and ore-forming mechanism of the Fule deposit were conducted.Several conclusions were drawn as below:1.The Obviously feature of sphalerite from fule deposits are riched in element of Cd,with content of 0.347 to 2.19,also contain a small amount of Ge,As,Se,Sb and other elements.In the figure of Fe-Zn,the data showed a good negative correlation showing Fe may replace Zn into the main sphalerite lattice.Compared with the content of Cd in sphalerite,galena content decreased significantly,indicating that Cd is easy to enter the sphalerite lattice.2.Dispersed elements in sphalerite of Cd from 7814 to 16983ppm,Ga from 2.23 to 684ppm and In from 0.1 to 3.13ppm.For the same sphalerite samples,the content of trace elements between the light and dark minerals are not significantly change.The content of trace elements in galena is lower than sphalerite.But content of element of Bi is one order of magnitude higher than that of sphalerite.3.All data were ploted near the marine carbonate rocks,reflecting CO2 is produced by the dissolution of carbonate rocks.34S values of sulfide are mainly concentrated in the 13?14‰,according to the characteristics of Fule deposits that ore-forming fluid may mainly come from the stratum.Area of crystalline basement(Kunyang group)and carbonate sedimentary strata may provide ore-forming materials for the deposit.