Study On Geophysical Characteristics And Uranium Prospecting Prediction In Hongshanzi Area Inner Mongolia

Hongshanzi uranium deposit is a typical volcanic type uranium molybdenum deposit in Guyuan hongshanzi uranium polymetallic metallogenic belt in China.Based on geological research,audio frequency magnetotelluric sounding,ground high-precision magnetic survey and IP intermediate gradient survey are used in this paper.Through data processing and interpretation,combined with geological and geophysical information obtained,the geological characteristics of hongshanzi area are analyzed,the following conclusions are drawn.1)Uranium metallogenetic conditions in Hongshanzi areaHongshanzi area is a small volcanic subsidence basin,which is controlled by NE and EW basement faults.The basement of the basin is Permian Dashizhai formation intermediate and acidic volcanic rock series,and the cover is upper Jurassic manketou OBO formation trachyte,tuff,rhyolite rhyolite porphyry,Neogene Pliocene Chifeng formation olivine basalt.The geological structure in the area is complex,the fault structure is developed,the magmatic activity is frequent,and it has the characteristics of multi-stage and multi cycle.There are strong activities from Paleozoic to Mesozoic Cenozoic,which provides a good tectonic environment for uranium mineralization.Geophysical survey results show that the strike of faults in the area is mainly NE and NW,and NE faults are mostly cut and staggered by NW faults,forming a network structure framework.NE trending faults are not only rock controlling structures,but also ore controlling structures.They are the ore accumulating places for uranium and molybdenum mineralization.Each ore belt is distributed in a certain range on both sides of the belt.The derived secondary structures provide a good ore hosting space for mineralization and are the ore hosting structures.Uranium and polymetallic mineralization in the study area is controlled by volcanic institutions,main faults and lithology.Uranium and polymetallic mineralization points and abnormal points mainly occur in the caprock of Upper Jurassic manketou OBO formation.The ore bearing lithology is mainly trachyte and rhyolite porphyry.The space of rhyolite porphyry distributed in NE direction is the place where the lava intrudes into the main crater.Most of the deposits and occurrences are distributed within hundreds of meters on both sides of rhyolite porphyry.2)Geophysical charactristics of Hongshanzi depositThe mineralization of hongshanzi uranium deposit occurs in the NE trending fault zone,and the mineralization is strictly controlled by rhyolite porphyry of volcanic neck facies and faults developed between different horizons.(1)It has the geophysical characteristics of strong magnetic field,low resistivity and high charging rate.(2)It is distributed near the magnetic field variation area,and there are weak magnetic anomalies near the strong magnetic field;the inversion resistivity is near the low resistance area in the high and low resistance gradient variation zone;and in the IP high charging rate anomaly area.3)The metallogenic prospect area is predictedAccording to the metallogenic and ore controlling factors in the area,combined with geophysical survey data,the uranium and polymetallic metallogenic conditions are analyzed,and three favorable metallogenic areas are predicted,including the Northwest hongshanzi Basin,the north side of yahaigou and anjiadian area.