Ore-forming Factors And Metallogenic Prediction Of Banshigou Iron In Baishan City,Jilin Province

The Banshigou area is located in the northeast of the North China Craton,the core and southern marginal of the Longgang compound anticline,which is a typical Outcropping area of the Archean metamorphic complex.The Banshigou Iron ore is a typical Anshan-type magnetite and belongs to the BIF iron deposit.The metamorphic deformation in this area on the structure control law of iron orebodies has obvious significance for predicting iron orebodies.This study combined with the basic data of the Baishigou iron ore,analyzed the formation age and geochemical characteristics,and studied the structural deformation of the Baishigou iron ore,and summed up the model of the Baishigou iron deposit and established the prospecting model.The Baishigou iron ore is located in the Archean high-grade metamorphic region,and hosted in the upper part amphibolite of the Archean Yangjiadian Formation.It is divided into gneisses,amphibolites,hornblende schists,magnetite quartzites and gneisses by rock composition.The main ore-bearing structures are amphibolite,hornblende schist and magnetite quartzite.The orebody appers in near bedded and lenticular shapes.The main ore types are quartz magnetite and hornblende magnetite.The ore body is contacted with surrounding rocks.The iron orebodies in Banshigou area have undergone the transformation of the later structure.The ductile structure has mainly affected the metamorphic deformation,enriched ore and distribution of ferrosilicon.The later brittle structure has affected the spatial distribution of iron deposits.According to the superposition of various structural elements' transformation relationships.structural element combinations,and structural trace geometry patterns,it was determined that the ore bearing formation has undergone three stages of metamorphic deformation and displacements,and formed a complex structural form.The fault structure caused the dislocation and displacement of the ore body,the surrounding rock and the three stages fold.The fault structures in the mining area can be divided into four directions: near EW,NE,NW and near SN direction.The ore-forming structural planes of the Banshigou area include: the axial surface of fold;the contact interface between thick amphibolite and gray-white quartzite(siliceous rock),hornblende schist.In this paper,combined with previous studies and this study,previous studies determined the formation age of the Banshigou iron ore,and obtained the zircon age of amphibolite and epidote amphibole schist both are 2548 Ma,and the zircon age of the direct host rock of iron ore(amphibole schist)is 2553±20 Ma in the Banshigou area,which was measured that the formation age of Banshigou iron should be ~2550Ma.This is consistent with the era of BIF ore in the region.The geochmeical characteristics show that ore is mainly characterized by silicon-enriched and iron-rich,with significant enrichment of high-field strength elements U,La,Ce,Sm,and P,and loss of high-field strength elements Th,Nb,Zr,Ti,and large-ion pro Stone elements Sr and K.According to the analysis of trace elements and rare earth elements,the metallogenic effect of the Banshigou iron ore is related to volcanism.According to the metallogenic characteristics of the Baishigou iron deposit,the metallogenic model of the Baishigou iron ore was initially established.Based on the prospecting mark,a preliminary prospecting model was established,and the further prospecting was made in the Banshigou area.and propoded the deep-deposit prospecting and wrinkle direction prospecting.