Yanshanian Granitic Intrusions And Their Polymetallic Mineralization In Northeastern Hebei Province

The study area is located in the northern margin of the North China Craton.It has experienced complex tectonic environment evolution for a long time,where there are a large number of granitoids,which is an important part of the North China Craton.Especially since Yanshanian,the northern margin of North China Craton has experienced the process of continental extension and lithospheric thinning from compressional environment.Therefore,the characteristics of rock mass and mineralization in this period are of great significance for the analysis of tectonic environment evolution.Based on this,in this paper,We made a detailed investigation of some typical rock masses in the eastern Hebei Province,analyzed the characteristics of rock masses and mineralization in different stages through chronology,petrology,mineralogy and geochemical characteristics,discussed the genesis of rock and its relationship with mineralization,and analyzed its response to regional structure.According to the chronological data of Jidong rock body,it is found that Jidong rock body is formed in Jurassic and Cretaceous.The Wangtufang and Madi rock bodies in this study were formed in the early Middle Jurassic.They are composed of granite and alkali feldspar granite,which belong to high potassium calc alkaline and peraluminous series.They are characterized by low Sr and low Y,and lack of Sr,Ba and other large ion lithophile elements.They are rich in Th,U,Nb,Zr,Hf and other high field strength elements,with different degrees of ? EU negative anomalies.In the evolution process,there are garnet and gold separated in the evolution process Crystallization.The Shouwangfen,Wazidian,Xiaosigou and Shuiliandong rocks were formed in the early Cretaceous.They are composed of quartz diorite,quartz monzonite porphyry,granite porphyry and quartz porphyry,which belong to the high potassium calc alkaline potassic series,and quasi aluminum peraluminous series,with obvious characteristics of high Sr and low Y,loss of Nb,Sr,P,Ti and other elements,enrichment of K,Zr,HF and other high field strength elements.? EU anomalies are not obvious,and hornblende and rutile are separated in the evolution process Crystallization.Wangtufang and Madi rock bodies formed in Jurassic belong to the same collisional granite,which originates from the thickened lower crust.The Cretaceous rock bodies are the same collisional granite and volcanic arc granite,and the tectonic environment is mainly in the late orogenic period.The lithosphere has extensional collapse and thinning.The magma source is mainly from the crust,but there is also the mixing of mantle derived materials.The magmatic related deposits in the study area include Madi rare metal deposit,Wazidian gold deposit,Shouwangfen copper poly metallic deposit,Xiaosigou copper molybdenum deposit and Shuiliandong copper deposit,all of which are later than the diagenetic age of the rock mass.Among them,Madi rare metal deposit is formed by highly differentiated magma evolution.For the Wazidian gold deposit,the magma carries the ore-forming material from the deep mantle,and provides heat for mineralization.For the skarn porphyry deposit,the magma provides the source of oreforming material and heat through contact metasomatism.