The Measurement And Anomaly Interpretation Of Radon And Its Daughters

Ordos Basin is an important productivity basin of sandstone type uranium deposits in China,At present,uranium deposits have been discovered in zaohuohao,Dongsheng,Nalinggou,Daying,Ciyaopu,maogaitu and Shuanglong,The proven reserves of uranium resources rank first in the uranium producing basins in China.According to the national evaluation of uranium resources potential,the basin has huge potential uranium reserves which is one of the preferred areas for uranium exploration in the future.However,due to the sandstone type uranium deposit in the basin is a concealed deposit,it is difficult to predict the metallogenic space of deep uranium deposits in the basin.It is urgent to carry out the research on the exploration technology of deep uranium resources and establish the spatial positioning model and geophysical exploration technology method system of sandstone type uranium deposits.Radon and its progeny measurement is a direct radioactive exploration method to find concealed uranium deposits.It is divided into instantaneous measurement and cumulative measurement.Instantaneous measurement includes conventional measurement of radon and ²¹⁰Po measurement of radon.The cumulative measurement includes the measurement of radon by?-track etching method,radon measurement by activated carbon adsorption method and other methods,such as ard-7 gamma ray full spectrum analysis measurement,high-purity germanium Gemini measurement,etc.Based on the theory of migration of radon and its daughters-the comprehensive model of geochemical halo in the stratum,this paper systematically studies the influencing factors and changing rules of soil radon migration,and analyzes the migration mode and typical forward modeling of radon in the stratum.According to the distribution characteristics of radioactive field which are analyzed by forward modeling.The single peak anomaly with a certain scale along the strike generally reflects the characteristics of gas passage-fault structure;the relatively gentle continuous anomaly belt with a certain intensity and scale generally reflects the characteristics of deep uranium mineralization;the gentle low anomaly area with a certain scale generally reflects the lithologic distribution area.Meanwhile,field work was carried out in Dongsheng area and Binxian area of Ordos basin with good geological and metallogenic conditions and loose overburden distribution.The effectiveness and anomaly interpretation methods of a series of radon and its progeny measurement methods,such as soil natural thermoluminescence measurement,²¹⁰Pomeasurement,²¹⁸Pomeasurement,trackmeasurement,ARD-7 gamma full spectrumanalysis measurement,activated carbon accumulation measurement,high-purity germanium Gemini measurement,are systematically studied.The application results show that:the effect of soil natural thermoluminescence intensity,track measurement,soil radon concentration,²¹⁰Po counting rate,ARD7 gamma ray full spectrum analysis measurement,activated carbon accumulation measurement and high-purity germanium Gemini survey are better.On the plane,the anomaly features are relatively continuous high value anomaly area with small gradient change and a certain scale,which generally reflects the favorable position of mineralization,while the gradient change The large and narrow absolute high value belt anomaly area generally reflects the gas passage?fault,etc.?,On the profile,the relatively high value abnormal stable section of"two high and one low"is reflected as the favorable position of uranium mineralization.In the process of interpretation of anomalies,it is considered that the abnormal values vary with the gas storage conditions of the surface soil layer,and the porosity of the overlying lithology of the mineralized body,the development degree of the micro structure,and the buried depth of the mineralized body have influence on the abnormal value and the shape of the curve.Meanwhile,the influence of other radionuclides is considered.For example,the analysis of soil sample nuclide shows that the influence of thorium in Dongsheng area is greater than that in Dongsheng area Therefore,various influencing factors should be considered in the actual anomaly interpretation,and the ore-induced anomaly should be determined by comprehensive analysis.In this paper,Looking for concealed sandstone type uranium deposits in the northern basin,the suitable methods of radon and its progeny measurement are as follows:soil natural thermoluminescence measurement,²¹⁰Po measurement,track measurement,activated carbon accumulation measurement,high-purity germanium Gemini measurement and so on.In particular,the combination and comprehensive interpretation of the above detection methods can accurately determine the favorable position of uranium mineralization.