Geological Geochemical Characteristics Of Hadamengou Gold Deposit

Hadamengou gold deposit is located in the western suburb of Baotou,Inner Mongolia,and the land structure is in the position of the taibei site in north China which is a large important gold deposit.In this paper,on the premise of fully collection of the mineral geological data,we study petrology,ore mineralogy,fluid inclusions of the mining area,and supplement the new observation and data of ore mineralogy and deposit origin,which form a further understanding of the mining area.The main metal minerals of Hadamengou gold deposit are pyrite,chalcopyrite,sphalerite,galena,etc.The nonmetallic minerals are mainly quartz and potassium feldspar.According to the study on the relationship of different minerals dressing by hand specimen and microscope,the mineral symbiotic combinations are:quartz-potassium feldspar-pyrite;Quartz-pyrite;Quartz-pyrite-sphalerite-galena-chalcopyrite;Quartz-calcite-magnetite–hematite.There are four corresponding mineralization stages:?I?quartz-potassium feldspar stage;?II?quartz-pyrite stage;?III?quartz-polymetallic sulfide stage;?IV?quartz-carbonate stage.The natural gold particles were observed in stage II and III,and the color of natural gold in stage II?average 945.20?was higher than that in stage III?average 930.60?.The natural gold particles were observed under electron microscope and scanning electron microscope,which existed in inclusion gold,fissure gold and crystal gap gold of quartz and pyrite.The natural gold particles were not observed in the chalcopyrite,but the electron probe analysis showed that there was a certain amount of gold in the chalcopyrite,indicating that the chalcopyrite was also an important gold-bearing minerals.The analysis electronic probe indicates that the early pyrite is deficient iron-rich sulfur,and with the progress of mineralization,the pyrite is deficient in iron and sulfur,which shows that the metallogenic environment is a process of the reducing sulfur escape.Its characteristic value Co/Ni,Au/Ag,S/Se,w?Fe?/w?S+As?all have the significance of indicating the genesis of the deposit.Hadamengou gold deposit is a NaCl-H₂O-CO₂ system of reducing temperature?288^oC—283^oC—216^oC?,lowersalinity?7.9wt%NaCl.eqv—6.9wt%NaCl.eqv—3.2wt%NaCl.eqv?,density changed little?0.81g/cm³—0.79g/cm³—0.77g/cm³?,and the deposit formed in middle and deep environment?1.2⁴.8km?.Previous studies on the hydrogen and oxygen isotopes in the region indicate that the metallogenic fluid is dominated by magmatic hydrothermal in the early mineralization,and the addition of atmospheric precipitation increases with the development of mineralization.