Genetic Mineralogy Study On Baijian Skarn Iron Deposit In Hanxing Area

Hanxing area is an important Skarn type iron ore concentration area in China.In recent years,with the development of deep prospecting work,a number of deep concealed deposits represented by Baijian iron ore have been explored.However,Skarn type iron deposits are ubiquitous in complexity and multi-genesis,which have long been controversial and controversial about the genesis and metallogenic process of iron ore.In this paper,the composition characteristics of magnetite in Baijian iron ore and rock mass in Hanxing area are analyzed.The genesis of Baijian iron ore deposit is mainly contact metasomatism,not magma penetration.Iron-rich magmatic hydrothermal fluid seeps and diffuses into contact zone and wall rock fissures under favorable fault tectonic conditions,and takes place contact metasomatism with carbonate wall rocks,forming Skarn type deposits.Through the mineralogical study of magnetite,it is found that the interlayer minerals exhibit high Mg and Mn low Fe²⁺characteristics compared with the contact belt ore;the contact zone magnetite shows a decrease in Fe³⁺and Ti content from early to late stage.The content of Si,Ca,Al and other elements increases;magnetite in the rock body is characterized by high Ti,Cr,V and low Mg and Mn compared with magnetite in the ore body;Fe²⁺and Mg in magnetite Mn exhibits a significant negative correlation;Fe³⁺exhibits a negative correlation with lithophile elements Si,Al,Ca,K,and Na.The composition and correlation of these elements have the characteristics of typical contact metasomatism deposits.It also shows a significant difference from the typical ore-forming magnetite mapping area.Through the mineralogical study of amphibole and plagioclase,it is found that with the magmatic rock intrusion,the temperature,pressure and water content in the ore-forming rock gradually decrease,and the oxygen fugacity gradually increases.According to the calculation of the all-aluminum temperature and pressure gauge,the deep magma chamber of Baijian iron ore is located at 18.7²0.2km underground,and the shallow part is subjected to the decomposition of amphibole with sodium-long petrochemical as the main surrounding rock alteration,providing for ore-forming hydrothermal fluid.Moisture and some Fe.In the compositional mineralogical mapping of magnetite,Al and Mg can be used to indicate the migration trajectory of hydrothermal fluid.By connecting the large white tower rock mass in the area,it can be inferred that the diffusion direction of the hydrothermal fluid is white from the deep part of the east.The magma chamber of the tower rock migrated to the stratum of the shallow research area in the west.