Application of airborne gamma-ray spectrometry in geological lithology mapping—a case study of a region in the Qinling Mountains, China

Abstract

Different types of rocks have different content and distribution characteristics of radioactive uranium, potassium, and thorium elements. Even for rocks of the same lithology, the content of radioactive elements varies due to different ages of formation, different origins, and different geological evolution processes. However, in various rocks and formations, the distribution of radioactive elements follows the general rule that the content of radioactive elements in igneous rocks is higher than that in sedimentary rocks, and increases with the acidity of the rocks. The younger the age of the rocks formed by the same type, the higher the content of radioactive elements. Based on this characteristic of radioactive elements in rocks, the author takes a region in the Qinling Mountains of China as an example. By using high-precision airborne gamma-ray spectrometry measurement data and existing geological information, the total content, K, eU, and eTh content, variation coefficient, ternary colour image, and other parameters of airborne gamma-ray spectrometry measurement are statistically analysed. The distribution characteristics of radioactive elements in various lithologies and formations in the area are studied, and the distribution rules are summarized. The rocks and formations in the research area are reclassified, and the typical fault structures in the area are analysed. The well-developed structural zone is mainly oriented in the northeast–southwest or north–northeast direction in the northern part and in the northwest–southeast direction in the southern part, which controls the favourable uranium mineralization zones in the research area.