The Origin Of The Massive Sulphide Ore Coexisting With V-Ti Magnetite Ore And The Magmatic Evolution From Hongge Deposit Baicao Section In West Sichuan China

Emeishan Large Igneous Province produces the largest V-Ti magnetite deposits in the word(Hongge,Panzhihua,Baima,Taihe).There is also a series of large,medium and small Cu-Ni-PGE deposits sporadic distribution.Hongge intrusion in the Emeishan large igneous province of Sichuan,reserves the largest V-Ti magnetite in China.The Hongge intrusion is closely associated with Emeishan basalt,syenite and granite.The age of Hongge intrusion is mainly about 257 Ma ? 259 Ma.The Baicao and Ma'anshan ore sections studied in this paper are part of the Hongge intrusion.They are located in the northern part of the Hongge intrusion.In the field geological survey work at 2012,the author discovered a new type of Ni-Co sulfide ore(body)that coexists with the Fe-Ti-V ore body in the Baicao section of the Hongge deposit.Field phenomena indicate that the massive sulfide ore and the Fe-Ti-V ore have formed in the same time.The content of Ni and Co in some samples reached the industrial grade.Current research shows that there are widespread disseminated sulfides in vanadium-titanium magnetite ores in Panxi area,but no coexistence of Ni-Co sulfide deposits and Fe-Ti oxide deposits has been found.By comparing the spatial location and mineral composition,mineral composition,and geochemical characteristics of vanadium-titanium magnetite,nickel-cobalt-sulfide ore,and various geological bodies,this paper proposes that the nickel-cobalt sulfide ore and the Hongge deposit rock mass and ore have The characteristics of homologous magma evolution.The enrichment regulation of ore-forming elements in all kinds of rocks and the iron titanium oxide ore shows an important characteristics in Hongge rock mass.injection iron ore can be devided into two phases.Early injection iron ore has the charecteristics of high PGE,while the late one has the charecteristics of low PGE.In fact,the invasion process of injection iron ore in two phases may be continuous or not.It experienced a small amount of sulphide liquation in the invasion process.Due to the partition coefficient difference of different elements in sulfide-silicate melt,the content of PGE and Cu loses a lot whlie the content of Co and Ni changes a little.When liquation of the sulfide melt occurs again in magma,plenty of Co and Ni enter sulfide minerals in Baicao ore block.The Cu/Pd ratio is higher than the prmitive mantel slightly in cobalt nickel sulfide,which is the product of deep magma chamber secondary liquation role.The sulphide ore that coexists with V-Ti magnetite in the Hongge deposit is the product of the saturating effect of the original magma in the deep magma chamber.With the gradual evolution of magma in the magma chamber,the sulphide's sulphidation occurred and the sulphide melt melted away.With the role of magmatic convection,tectonic movement and thermal movement,the sulphide melt and the iron-rich melt intruded into the Baucao section,forming a massive sulfide ore that coexists with the Fe-Ti oxide.The disseminated sulfides widely found in the Hongge deposit are the result of late crust contamination.We suggest that Hongge deposit in the deep magma chamber is affected by Transmagmatic Fluid Hypothesis after the basaltic magma eruption and microcrystalline gabbro and ferruginous basic rock emplacement.Transmagmatic Fluid and silicate melt carried a large number of olivine and pyroxene crystals rise and emplacement to formed the ferruginous ultrabasic rock.Deep source magma chamber is further affected by Ti-rich fluids addition.The magma chamber appeared a strong magma convection that promote the magma chamber appeared immiscibility and formed syenite melt,Fe-Ti oxide fluid(iron pulp),sulfide melt,plagioclase melt(or elongated stone).Followed by intrusive activities of penetrating iron ore,massive nickel-cobalt sulfide and syenite appeared.