Urainium Metallogenic Conditions And Prospecting Direction In Tuquan Basin, Inner Mongolia

Tuquan basin is located in the southern section of Zhalantun uranium mineralization zone,which belongs to the shore Pacific tectonic metallogenic domain Daxinganling metallogenic province.Restricted by frequent and intense volcanism in Mesozoic,uranium deposits of volcanic type developed.A number of valuable uranium deposits?or points?have been found in this area,such as Hongshanzi uranium-molybdenum deposit,NO.701 uranium deposit and NO.8 uranium points,No.48 uranium points.Through this geological survey and research work,on the basis of a brief description of the regional geological background,this paper focuses on the analysis of the formation,structure,magmatic rock,alteration,volcanic activity,geophysical characteristics,abnormal mineralization and other aspects of the tuquan basin,and preliminarily draws the following conclusions:The basement of the basin is mainly composed of the Caledonian,the late Variscan,the early Yanshanian crust-mantle remelting granite and a set of intercontinental clastic sedimentary formations of the early Permian,continental intermediate-acid volcanic lava,pyroclastic rock formation,and continental clastic rock mixed with intermediate-acid volcanic rock formation of the late Permian.The basement rocks have undergone multiple stages of tectono-magmatic activity,which has led to the continuous preenrichment of uranium.The volcanic rocks of the three strata of the basin,namely,the Manketouebo formation,the Manitu formation and the Baiyingaolao formation,are the most widely developed and thickest.Volcanic lava,clastic rock and volcanic sedimentary rock alternately appear and form different interfaces,which are the sites where the mechanical physical and chemical properties of different acid rocks vary greatly,and are the favorable sites for uranium mineralization and occurrence.Three NE-trending fractures with significant rock-controlling and ore-controlling effects were identified,namely,Huanggangliang-Ulanhot fracture,Nenjiang fracture and Daxinganling ridge fracture.Mesozoic-cenozoic basement structure was resurrected and formed a special grid structure,which controlled the distribution of uranium mineralization in this area.Through the controlled audio magnetotelluric sounding section,the deep distribution of volcanic rocks and intrusive rocks in this area was clarified,and the location and development of structures in the deep region were found out.The strata mainly consists of volcanic rocks of the Manketouebo formation,the Manitu formation and the Baiyingaolao formation,with few metamorphic rocks.Magmatic activity is intense and a large area of granite runs through the eastern part of the basin.On the whole,the intrusive rocks of the early Yanshanian were mainly developed in the north-western side,and there are fewer intrusive rocks in the south-eastern side.The structural inclination in the area is mainly SWW and SEE,and the dip Angle is mainly 85 degrees.Fault structure is the migration and storage space of uranium.The development of deep structure is very important to search for deep blind ore body.Through the surface gamma total volume measurement in Keyouqianqi,it was found that the irradiation rate and U,Th and K content of intermediate-acid volcanic rocks were higher,while the irradiation rate and U,Th and K content of sedimentary rocks and metamorphic rocks were lower.The U element in the coarse granites in the basement migrated and its content was lower than the background content,providing the uranium source layer for the basin.A total of 16 high field,17 high field,12 abnormal field,1 uranium mineralization point and 1 uranium anomaly point were delineated.The gamma high field and anomaly field are mainly distributed in the middle acid volcanic rocks and acid intrusive rocks of the upper Jurassic,and distribution forms are controlled by NE,NW and SN trending faults in the region,located at the intersection of the two tectonic groups.The radioactive anomalies on the surface of these sites have a good indication for the exploration of deep uranium mineralization^[33].Through the investigation of groundwater radioactivity,4 abnormal radon halos and12 abnormal gamma fields were circled.Abnormal radon halos and abnormal gamma fields are concentrated in the intersection of NE,SN and NW faults or the intersection of faults and volcanic structures,obviously controlled by volcanic hydrothermal fluids.A series of alterations related to uranium mineralization have been formed?Verified by surface survey and remote sensing interpretation data?,providing favorable clues for the search for deep uranium mineralization.Through the interpretation and analysis of remote sensing data,a group of NE and NW trending fault structures were found.A beaded ring structure developed in the distribution area of volcanic rocks is obviously controlled by faults,which can be inferred as a volcanic mechanism.The results show that uranium mineralization is closely related to volcanic mechanism.In addition,through the analysis of the distribution of the interpreted anomalies,it is found that the iron stain is obviously controlled by the structure and developed between two NW ore-controlling structures.Part of the iron stain anomalies may be related to mineralization alteration,which provides an important clue for the search for deep uranium mineralization enrichment.Based on the comprehensive analysis of uranium mineralization types,metallogenic conditions and ore-prospecting information in Tuquan basin,a metallogenic prospective area in Keyouqianqi and a ore-prospecting target area in Taipingtun were delineated.There are obvious mineralization,geophysical anomaly and chemical anomaly of water,and uranium ore in this area.Structures,hydrothermal transformation and other basic metallogenic conditions are favorable.In this area,the superposition of the surface gamma anomaly,the uranium mineralization and the fracture alteration zone,the intersection of NE and NW faults,are the key points of the next work.