Application Of Petrographic Mapping Technology Of IOCG Deposit In Baixijiao Section, Dongchuan, Yunnan

Applications of lithofacies mapping had been promoted at the deep Baixina ore section,based on comprehensive geological logging for underground drillholes and adits in Lanniping Iron-copper field,as well as the characteristics of zonation of lithofacies and ore-mineral,and the magnetic susceptibility and density characteristics of ores and lithofacies.The following are the major progresses and inclusions.1.According to the characteristics of susceptibillity and density of ores,at the deep part of Baixila district,ore-types can be classified to the type-ore with high-susceptibillity high-density,the type-ore with low-susceptibillity high-density,the type-ore with middle-susceptibillity middle-density and the type-ore with low-susceptibillity low-density.The relationship between the susceptibillity and density and tenor of titanium grades and iron grades from the ores studied are positively correlated.2.The distributions of the IOCG orebody hosted in the third member of the Yinmin Group mainly might be controlled by intrusion of alkaline complexes(i.e.,dikes or branches)in this study.The IOCG orebody are mainly hosted in two tectonic belt of the alkaline complexes.One is distributed in the explosive breccia belt mainly located at the top of he alkaline complexes.Another is distributed in the inner part,hosted in the hydrothermal breccia zone,of the alkaline complexes.The susceptibillity and density of the IOCG orebody are apparently higher than these in its country rocks.Thus,the susceptibillity and density of ores and country rocks can be used as the direct mark of IOCG deposit in the third member of Yinrmin Group.3.The study of lithofacies characteristics at the deep Baixina ore section show that lithofacies have obvious zoning characteristics from the center to country,expanded around alkaline complexes dikes,from center facies of intrusive rock to transitional facies of intrusive rock to carbonate sedimentary facies,and their magnetic susceptibillity and density change from high to low.The IOCG orebody is mainly hosted in the transitional facies of intrusive rock and the center facies of instrusive rock.The susceptibillity and density of different lithofacies are the auxiliary prospecting mark of IOCG orebody.4.There are both apparent ore zonation and lithofacies zonation in the tilt direction and along the trend direction of IOCG deposit.(1)In the tilt direction,there are iron oxide facies and copper sulfide facies in the top of orebody,iron/titanium oxide facies and magnetite facies in the middle and copper sulfide facies on the base.(2)Along the trend direction,there are mainly copper sulfide facies,iron oxide facies and titanium facies in the western IOCG orebody,cupriferous magnite facies in the middle,and copper sulfide facies in the eastern part.And the magnetic susceptibility and density of ores have zoning characteristics,and have positive relation with the tenor of iron ore and titanium ore in the IOCG orebody.