Research On Comprehensive Geophysical Prospecting Method In Sandstone-type Uranium Exploration In North Eastern Margin Of Ordos Basin

As a strategic resource of China,uranium mines are related to many aspects such as national defense,nuclear power ac basins in Xinjiang and Inner Mongolia.Over the years,nuclear geologists have tried numerous methods,trying to use other technical means to conduct preliminary explond national economic construction.Since the 1990s,the nuclear industry system has found 10,000-ton large-scale in-situ sandstone-type uranium deposits in several Mesozoic and Cenozoiration and evaluation,and to minimize drilling construction.Because the Quaternary cover is often thick in the basin,there are few rock outcrops,which seriously limits the application effect of conventional geological methods.Practice has proved that various geophysical methods have different application effects in basin structural division,stratigraphic correlation and sand body delineation,sedimentary environment understanding,redox boundary and mineralization information identification.Therefore,it is necessary to establish an effective combination of geophysical methods for sandstone-type uranium exploration and to establish an information inversion model.From the theoretical and practical aspects,the effects of various geophysical methods on the exploration of sandstone-type uranium deposits in the basin are comprehensively analyzed,and the prospecting basis for geological exploration is provided as much as possible to guide the drilling construction.The Ordos Basin is an important energy base in China,containing oil,natural gas and coal resources.The corresponding departments have done a lot of basic geological work.The exploration of minerals is mainly oil and coal.The exploration of oil,natural gas and coal geology began in the 1950s.The North China Geological Bureau of the Ministry of Geology and Mineral Resources conducted a large-scale census in the northern part of the Ordos Basin.The situation and the distribution and causes of the coalfields were initially evaluated.The uranium geology work began in 1958,and it was not until 2000 that it was issued by the China Nuclear Industry Geology Bureau.The nuclear industry 208 brigade and other units successively carried out mapping research,special research,uranium resource survey evaluation and exploration,etc.A breakthrough in progress.The Ordos Basin in the Ordos Basin is located in the western part of the North China Platform and is part of the North China Platform.It has a long history and a long evolution time.It is a multi-cycle superimposed basin and is a relatively stable and complete structural unit existing in China.The Bouguer gravity anomalies in the northern part of the basin are simple in shape and gentle in change,and the anomalies are mainly distributed in north-south or east-west strips.The Bouguer gravity anomaly at the edge of the basin is relatively high,and the Bouguer gravity anomaly in the basin is relatively low.The regional magnetic field characteristics mainly reflect the magnetic differences of the Archean and Proterozoic rocks in the crystalline basement of the Ordos Basin and the structural morphology of the basement.The shape of the north magnetic anomaly field is relatively simple.The magnetic anomaly field in the whole area changes gently,and the positive and negative magnetic anomalies change little,generally-250nT³30nT,and the local magnetic anomaly can reach-500nT⁹00nT.The geophysical characteristics of the northern aeroplane mainly reflect the difference in the radioactive elements content of the exposed strata,and also reflect the changes in the modern radioactive geochemical environment.The strata in the eastern part of the stratum are more comprehensive,but the lithology is simpler,the structure is not developed,and the stratum is flat.In addition to the upper carboniferous system,the radioactive gamma irradiation rate is low,and the gamma value variation interval is small.In this paper,the natural potential method,²¹⁰Po measurement,and audio magnetotelluric comprehensive geophysical exploration method are used to study the Xinjie-Hongshixia section in detail.According to the natural potential method,the position of the redox transition zone is inferred.The ²¹⁰Po measurement results are in good agreement with the 1:250000 industrial hole drilling effect of the working area.The exposed magnetotelluric is the exposed uranium mine.The construction of the survey works provides an effective basis.The co mbined use of the three methods can analyze the underground geological structure,and at the same time characterize the stratified information and the structure of the mining area,so that high-precision deep detection and delineation can be realized.Various geophysical methods are used in basin structural division,stratigraphic correlation and sand.Body ring setting,sedimentary environment awareness,redox boundary and mineralization information identification have different application effects.