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Airborne gamma ray spectrometry (AGRS) measures the gamma-rays that are emitted from naturally occurring radioactive isotopes found in rocks and soil, the most abundant of which are potassium (K40), uranium (U238), and thorium (Th232). Radiometric data can aid in exploration of critical mineral resources, including deposits of barium, fluorine, titanium, beryllium, niobium, rare-earth elements, and uranium. There is also growing interest in using radiometric data to map soil properties.


The airborne radiometric data are an example of compositional data that are non-stationary (that is, the mean and the standard
deviation vary spatially). It is therefore important to apply statistical techniques that account for both properties when creating maps. To this end, a Bayesian hierarchical model coded in the Stan probabilistic programming language is used to estimate spatial variations of the mean and standard deviation in K40, eU238, and eTh232. Using the 2005 national airborne radiometric data compilation, new maps for the conterminous U.S. are being created for these three radioactive isotopes.

Science Support Framework Category: Science Data Lifecycle - Analysis

Author(s): Margaret Goldman (mgoldman@usgs.gov) - Geology, Geophysics, and Geochemistry Science Center



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