Geophysical Characteristics And Prospecting Prediction In The East Of Xiangshan Basin

At present,the discovered uranium deposits and research work in Xiangshan Basin are mainly concentrated in the west and north,while the research work in east such as Yunji,Taizhou and Yaogang is poor.The study on the main ore controlling factors such as deep geological characteristics and uranium mineralization information is poor,which restricts the study and exploration of uranium mineralization in the East.Using comprehensive geophysical methods to analyze uranium metallogenic environment and radioactive characteristics in eastern Xiangshan basin and predict prospecting are of positive significance to expand prospecting results in Xiangshan ore field.Based on geological research,audio-frequency magnetotelluric survey,ground?-ray spectrometric survey,soil²¹⁰Po survey,data processing and interpretation,the uranium metallogenic conditions in the east of Xiangshan Basin are analyzed,and the prospecting target and metallogenic prospect area are predicted,combined with geological and remote sensing information.According to the analysis and research,the following is concluded.1)Geophysical characteristics of eastern Xiangshan basinThe higher?-ray spectrum uranium contents in the study area are distributed in Youfang,Lijiashan,Liaoli and Taizhou,and most of them are close to the contact zone between porphyry granite and porphyritic lava of Lower Cretaceous,F₁,F₁₂?F₃and F₂₀?The variation coefficient of?-ray spectrum thorium contents is small.The?-ray spectrum thorium contents are distributed along F₁,F₃,F₂₀,F₄ and the extension direction of the faults.The?-ray spectrum potassium contents are same with thorium.The higher?-ray spectrum potassium contents are distributed along F₁ and F₃.The halo of soil ²¹⁰Po is high in the north and low in the south of the study area.The anomalies of soil ²¹⁰Po are concentrated in Youfang,Lijiashan,Shangan and Yaogang and most of them are distributed along the contact between porphyry granite and porphyritic lava of Lower Cretaceous,F₁,F₁₂,F₃,F₄and the extension direction of the faults.The electrical structure of the study area presents as low resistivity in the shallow part,high resistivity in the deep with banded low resistivity in some area.Uranium mineralization environment is characterized by low resistivity.2)Uranium metallogenic conditions in eastern Xiangshan BasinThe eastern part of Xiangshan Basin is located at the intersection of EW-trending basement fault and NE-trending caprock fault,with abundant hydrothermal activity.The porphyritic lava and subvolcanic rocks of the Lower Cretaceous are favorable ore-bearing surrounding rocks,and the low-order NE-trending,NS-trending and NW-trending faults,fissures and interfaces between volcanic rock groups provide a good ore-bearing space for uranium mineralization.Anomalies of the?-ray spectrum uranium-thorium-potassium contents are closely related to subvolcanic rocks and nearly NS and NNE trending faults.The ²¹⁰Po anomalies range are more wider than the?-ray spectrum,and it shows that the deep part of the area has great prospecting potential.Electromagnetic measurement shows that the thickness of volcanic caprock in Yunji area and its northern part is over 800 m,and the denudation degree is moderate,so it has certain conditions for ore preservation.The subvolcanic rocks and the main ore controlling faults extend to the deep and are stable,which has a certain prospecting space.3)Prospecting prediction in eastern basinLijiashan and Youfang are delineated as 2 prospecting targets.Liaoli is delineated as class-?metallogenic prospect area,while Taizhou is delineated as class-?.