Airborne gamma-ray spectrometry: potential for regolith - soil mapping and characterization
Résumé
Airborne gamma-ray spectrometry provides continuous regional geochemical information (i.e. ground concentrations of Potassium (K), Thorium (Th) and Uranium (U)). In the frame of a collaboration between BRGM (the French geological survey) and INRA (the French soil institute), joint research was achieved to recognize the effect of weathering and to assess soil variability using gamma-ray data. We first document that gamma signals are clearly influenced by weathering and pedogenetic evolution. Zonal statistics performed between existing soil maps and airborne gamma-spectrometric data evidence, for a given substratum, variations of radiogenic elements consistent with soil sequences. The second result obtained demonstrates, in a sedimentary environment, the ability of gamma-spectrometric data to predict regional regolith-soil parameters. Through multiple linear regressions between ground parame-ter measurements and airborne gamma data, gamma-spectrometric information was clearly identified as a co-variate of ground physical and chemical properties.