The Study Of Physical-Chemical Conditions In Process Of Ore-Forming Fluid Migration And Precipitation In Maoping Lead-Zinc Deposit,Zhaotong,Yunnan

For exploring variety of migratory patterns and parameters of the various physical and chemical conditions in process of lead、zinc migration and precipitation,the paper relies NSFC-Yunnan Joint Fund’metallogenic mechanism research and target optimization of rich Ge-bearing Pb-Zn polymetallic deposits concentrated distric in Northeastern Yunnan’ and school-enterprise cooperation projects ’deep and peripheral concealed ore prospecting forecast and increasing reserves of Zhaotong large lead-zinc deposits’.Through the data collection and comprehensive analysis of the former research results,the thesis make the exploratory research on the basis of the outdoor geological survey.The main analytic methods includes the comprehensive approach,mineralogocal approach,petrological approach,fuild geochemical approach,geological thermodynamics and fulid inclusion approach aiming at the ore-forming physicochemical conditions,element migratory patterns and precipitation conditions,lead and zinc symbiotic differentiation mechanism,HZT-type lead-zinc deposits mineral assemblages vertical to zoning mechanism.The main achievements are made as follows:(1)Though the research on forms migration and precipitation conditions of lead and zinc in Yunnan Zhaotong the HZT-type lead-zinc deposits by using of thermodynamic calculations and preparation of the physicochemical phase diagram,the results show that:the main migration form of lead and zinc in hydrothermal fluids is chlorine complex in Zhaotong lead-zinc deposits.In addition,the thesis gain the the parameters of the physical and chemical conditions of sulfide precipitation,such as log/O2,logfO2,loga,logfCO2,pH,Eh and so on.(2)The thesis recovers the physical and chemical conditions of the uninstall and precipitation stage of ore-forming fluids in Zhaotong lead-zinc deposits.Though the logfO2-logfS2 phase diagram,we obtaine the oxygen and sulfur fugacity conditions and variation with temperature trend of the single mass of lead,zinc,and their oxides,sulfides.According the pH-logfO2 phase diagram and the pH-loga phase diagram,the advantage field of chlorine complex or sulfur complexes for lead-zinc can be gained,and research the constraints of pH,ionic concentration for sulfide precipitation by using the phase diagram.Further more the physical and chemical conditions in process of migration、precipitated of the ore-forming fluid,lead and zinc symbiotic differentiation and mineral assemblage zonation mechanism will be discussed.(3)The thesis obtain the advantage field for the various presence form of elements such as Pb,Zn,Fe,S,C,Ca,etc.under the different physical and chemical conditions though the phase diagram.(4)On the basis of the summarized the types and characteristics of fluid inclusions in Zhaotong lead-zinc deposits,and clarified generations and Stages of the fluid inclusions,use the microthermometry technology to obtaine homogenization temperature of sphalerite mineral inclusions in deep I-10 orebody.These provide important evidence for an in-depth study of the evolution of the fluid.