Study On Application Effect Of Integrated Geophysical Exploration Method In A U-Mo Mine Area

Several geophysical methods are used in a U-Mo mine area,Guyuan,Hebei.By conducting ground gamma-ray spectrum,radon survey with activated charcoal,high-precision magnetic survey and Audio-frequency magnetotelluric survey,in order to summarize a set of efficient geophysical exploration methods in this area,Some geophysical anomalies are identified after the mathematical statistics and analyzing.Furthermore,two prospects are outlined according to the principle of anomaly consistent degree,structure development and rock mass exposure.1.High-precision magnetic survey is carried out there to obtain the distribution of magnetic field.Two high magnetic anomalies are named as c-d-1 and c-d-2,which are respectively deduced as results of a shallower magnetic body with a depth between 50 m to 100 m and a deeper one after some processing of RTP,up-continuation and anomaly separation.And,It is concluded that uranium mineralization are mainly located in the magnetic field background or the transition zone between positive and negative field values.Audio-frequency magnetotelluric survey results show the location,occurrence and width of faults such as FH(II)-4,FH(II)-3 and FH(II)-2.At DGC2 profile,among horizontally 800-1050 m and 800-1300 m in elevation,there is an anomaly with high resistivity of above 400 ?m,which is referred as sub-fluvial porphyry rock mass.The overlying strata with lower resistivity are considered with mineralization.2.Ground gamma ray spectrum survey is conducted and the distribution of U content,Th content,K content and total intensity is obtained.The average of eU% and coefficient of variation are analyzed and the result shows most lamellose and massive potash feldspar rhyolite in study area with a relatively high background value and big coefficient of variation.Through analyzed U-Th ratio value and U-Ra sampling result,it is deduced that U element in southern and eastern is leaching and transporting towards north of the study area and then enriching there.3.Radon survey with activated charcoal locates several anomalies,mainly in north and south area.Synthetically considering the U content of gamma ray spectrum and Rn concentration which indicate Uranium prospecting,a factor multiplied by these two values are given and seven Uranium prospecting anomalies are shown in the map.As the prospecting mark,the anomalies are classified into 3 grades,which are YBQ-1,YBQ-2,YBQ-6 in first grade,YBQ-7 in second grade,as well as YBQ-3,YBQ-4,YBQ-5 in third grade.On the basis of comprehensive geologic and geophysical study,prospective area I and II are delineated.Some suggestions are given to accelerate exploration work in area I and conducting verification Work in area II.Finally,it is concluded that the combination of this method has a fast and effective conclusion in the exploration of volcanic rock type uranium ore.