砂岩型铀矿土壤光释光特性及测量流程优化OA

Sandstone-type uranium deposits are recognized as the main type for uranium exploration and mining in China,owing to their large reserves and ease of extraction.However,some of the sandstone-type uranium deposits are covered by thick overburden layers and buried at relatively great depths,which make the conventional methods difficult to obtain effective measurement results.In this context,soil thermoluminescence(TL)and optically stimulated luminescence(OSL)measurement methods,which both belong to the category of cumulative radon measurement,have shown good applicability in sandstone-type uranium exploration,because these methods have the advantages of long accumulation time of uranium ore body radiation information and low interference from environmental factors.Nevertheless,there are two limitations in the soil OSL measurement process:The first is the relatively complex soil chemical treatment procedure,which is difficult to satisfy the requirements for the large number of samples in uranium exploration;The second is the relatively low radiation response of quartz,which causes the OSL measurement to be insufficient in identifying weak anomaly information,and is unable to satisfy the precision requirements of exploration.In order to resolve these limitations,this study conducted a series of experiment to address the above issues.Accordingly,the distribution characteristics of the soil OSL signal and its corresponding mineral sources were firstly analyzed.Subsequently,the minerals for the OSL signal measurement were selected based on the intensity of the stable OSL signal under different soil chemical treatment procedures,and the measurement process was optimized.The experimental results indicate that the main source of soil OSL signals under different soil chemical treatment procedures is the 100-300℃TL signal from quartz and feldspar minerals,with carbonate rocks contributing only a minor portion of the OSL signal.Furthermore,organic matter within the soil can reduce the intensity of OSL signal.The soil OSL signal intensity increases initially and then decreases under different soil chemical treatment stages.The soil OSL signal intensity is highest when the soil contains only quartz and feldspar.Therefore,the identification capability of weak anomaly information in the sandstone-type uranium deposits can be enhanced by selecting quartz-feldspar admixture minerals as measurement samples.Based on the above results,the optimized method was applied to the exploration of a certain sandstone-type uranium deposit in Inner Mongolia after simplifying the soil pretreatment processes.The results show that,compared with the measurements of soil instantaneous radon and ground γ-ray spectrum,only simple data processing is required by the optimized method to delineate the favorable metallogenic zones along the exploration profile.This study can provide crucial technical references for the application of the soil OSL exploration method in the deep exploration of sandstone-type uranium deposits.