Ore Mineralogy Characteristics Of The Heiniudong Ore Section Of Liwu Copper Mine, Jiulong County, Sichuan Province And Its Research Significance

The Heiniudong ore section of this paper is located in the Liwu copper ore field of Jiulong County,Sichuan Province.The predecessors have many systematic studies on the Liwu copper deposit,and they believe that its mineralization has many stages and multiple genesis.However,there is a big difference in understanding of the metallogenic age,metallogenic period,metallogenic stage and main ore-controlling factors.Based on previous studies,this paper attempts to study the macroscopic basic geological features of the Heiniudong ore section of the Liwu copper deposit,and combain the structure of the ore section and the typical mineral composition of the ore.Main research on observing the mineralogy characteristics of typical ore in different ore bodies.Through the contact relationship between minerals,the sequence of mineral generation to judge the metallogenic stage and metallogenic stage.It provides important reference information for revealing the genesis of the Heiniudong copper deposit and determining the metallogenic period,metallogenic stage and main ore-controlling factors.By collecting data and reading the literature,it is understood that the Heiniudong ore section locates in the southwestern margin of the Yangtze plate and the southeastern margin of the Songpan-Ganzi orogenic belt in the geotectonic structure,which is part of the Jianglang dome.The annular detachment fault zone around the development of the Jianglang dome is the main ore-controlling structure of the mining area.The ductilebrittle fault developed in the area is the main ore-bearing and ore-conducting structure in the mining area.Liwu rock group is the main ore-bearing stratum of the copper deposit in the Heiniudong section.The mineralogy characteristics of the ore indicate the main ore types in the Heiniudong ore section are dense block ore,disseminated ore,strip ore,clump ore,veined ore and breccia ore,a total of six species.The main ore structures are massive structures,disseminated structures and strip-like structures,and some ore develop breccia and vein structures,a total of five species.The structure of the ore is mainly a self-formed crystal structure,semi-automorphic crystal structure,crystal structure and co-edge structure formed by crystallization;an etched structure,a residual structure,a reaction edge structure,and a literary structure formed by the filling;an oriented or disorderly distributed opacifying structure formed by the separation of solid solutions.Pyrrhotite is the most abundant metal mineral in the ore section.Chalcopyrite is the main copper-smelting mineral in the ore section.In addition,sphalerite,galena,and a small amount of pyrite,ilmenite,gold and silver ore are also developed in the Heiniudong ore section.The most common mineral combination is the pyrrhotitechalcopyrite-sphalerite and the mineral combination of galena-sphalerite.The gangue minerals are mainly quartz,biotite,muscovite,chlorite,tourmaline and garnet.The solid solution separation structure developed in the ore,when sphalerite is used as the main mineral,indicates that the ore-forming temperature is above 350 ?;when chalcopyrite is used as the main mineral,it indicates that the ore-forming temperature is around 500 °C.A large number of high-temperature mineral pyrrhotite,tourmaline and garnet are developed,indicating a high ore-forming temperature.At the same time,a low-temperature mineral combination sphalerite-galena is also developed,indicating a wide range of ore-forming temperatures.Through the distribution of main,trace elements and rare earth elements in the ore,it is indicated that the formation environment of chalcopyrite is iron-rich and sulfur-poor,and sphalerite is rich in iron;the ore section also develops beneficial associated elements Au,Ag,S,Co,Pb,As,Mo,Bi,Ge,etc.Combined with the standardized distribution pattern of rare earth element chondrite,the rare earth elements in the ore may be derived from surrounding rock.Through the ore fabric,the inter-mineral relationship and the mineral symbiosis combination,the sub-segment of the ore-forming period of the Heiniudong ore deposit and mineral generation sequence table are drawn.It is divided into four stages: sedimentary enrichment period,tectonic deformation period,hydrothermal mineralization period and surface leaching period.The hydrothermal mineralization period is divided into two stages: medium-high temperature hydrothermal mineralization stage and medium-low temperature hydrothermal mineralization stage.Through the uniform temperature test of the fluid inclusions,the mineralization temperature is at least 110.7 ?,and the highest temperature is above 400 ?,which is consistent with the temperature of the ore mineral combination and the solid solution separation structure.Combined with the stable isotope combination in the ore,it is suggested that the silicon isotope may be derived from metamorphic rock series,and the sulfur isotope may be two sources of mantle and seawater.Combined with the distribution of ore,trace elements and rare earth elements in ore and rock,it indicates that the source of ore-forming materials may be shell source and earth's crust.The Liwu rock group is a sedimentary structure of sand-gravel clastic rock-based volcanic rocks.The debris is derived from the earth's crust,so the ore-forming material may be derived from the earth's crust.Combined with hydrogen-oxygen isotope mapping,it is indicated that the fluid source is mainly metamorphic water and magmatic water.And the ore structure formed by extensive development of filling,indicating that the formation of the deposit is related to hydrothermal action.Combined with extensive magmatic intrusion and regional metamorphism in the area,the hydrothermal fluid may be a mixed hydrothermal fluid with metamorphic and magmatic hydrothermal fluids.The regional tectonic characteristics,ore geological characteristics,ore mineralogy characteristics,ore-forming materials and ore-forming fluid sources and migration mechanisms of the Heiniudong section of the Liwu copper mine,as well as the study of mineralization dynamics and metallogenic ages,the deposit is a mediumhigh temperature hydrothermal filling metamorphic deposit related to regional tectonic metamorphism and metamorphism-magmatic hydrothermal fluid.