Characteristics Of Hydrogen And Oxygen Isotopes,Fluid Inclusions And Fluid Evolution Of The Fengning Ag (Au) Deposit,Hebei Province:Comparing With Decratonic Gold Deposits

Fengning Ag?Au?deposit is a Ag?Au?ore deposit of Cryptoexplosive breccia,located in one segment of west pacific ring,and the tectonomagmatic belt of Baiyin ditch-Tiger ditch door.It systematically induced and concluded the Fengning Ag?Au?deposit of the regional geological background,geological characters of deposits and ore feature in this paper.On the basis of overall field investigation and indoor research,we have divided ore-forming stages of the hydrothermal period.By the methods of Raman spectrum,hydrogen and oxygen isotope test and temperature test,the inclusions found in the Fengning Ag?Au?deposit have been tested and analyzed.The ore deposit genesis is analyzed and take the results of tests compared with the decratonic gold deposits,predict the deep metallogenic conditions of Fengning Ag?Au?deposit.The hydrothermal period of Fengning Ag?Au?deposit has four mineralization stage,i.e.,Siliceous rock stage,Pyrite-quartz stage,Polymetallic sulfide stage,Fluorite stage.There have three sub-stages in the fluorite stage: purple fluorite sub-stage,green fluorite sub-stage and white fluorite sub-stage.The measured data of the hydrogen and oxygen isotope test from the Fengning Ag?Au?deposit is concentrated in the bottom left of magmatic hydrothermal fluids,It is close to the meteoric hydrothermal fluids.so the hydrogen and oxygen isotope analyses show that the hydrothermal solution of the ore-forming stage was derived from the magmatic hydrothermal fluids and the fluid of the deposit was a mixed source of magmatic water and atmospheric water.Fluid inclusions are mainly dominated by three distinct tyes,i.e.,L-V,pure liquid,gas inclusions and three phase containing CO₂ inclusions.However the amount of three phase containing CO₂ inclusions is very little,so we did not do research here.The homogenization temperature of the fluid inclusions in the 4 stages range is mainly between 150 ? to 300 ?,the salinity of the fluid inclusions concentrate mainly on 0.5%⁶%,the density of the fluid inclusions concentrate mainly on0.65g/cm³¹.02g/cm³,and the ore-formation fluid pressure concentrate mainly on5×105Pa¹10×105Pa,the depth of metallogenesis is 0.05 km¹.12 km.As the time of ore-forming,the homogenization temperature of the fluid inclusions,homogenization temperature of the fluid inclusions,the ore-formation fluid pressure and the depth of metallogenesis decrease while the density of the fluid change little.Above all,basing on the analysis of the hydrogen and oxygen isotope,Fengning Ag?Au?deposit is a typical continental volcanic type deposit with low temperature,medium density and shallow-seated features.Comparing the hydrogen and oxygen isotopes data,homogenization temperature,the salinity and the depth of metallogenesis of the Fengning Ag?Au?deposit with the Decratonic Gold Deposits,we find that the metallogenic temperature of Fengning Ag?Au?deposit is similar to Jiaodong gold deposits and explosive breccia-type deposit which are related to cratonic destruction.The depth of metallogenesis,the salinity of the ore fluid and the content of magmatic hydrothermal fluids of Fengning Ag?Au?deposit are less than explosive breccia-type deposit.So combining the present research,we think that the formation of Fengning Ag?Au?deposit is related to cratonic destruction,the Fengning Ag?Au?deposit in deeper is likely to become lead-zinc-gold ore deposit.