Statistical interpretation of airborne gamma-ray spectrometric data using factor analysis

The statistical technique of factor analysis provides a quantitative and non-subjective means of synthesising and correlationg data from gamma-ray spectrometry surveys. Factor analysis was applied to data from an aerial survey of the Freer-Three Rivers area in South Texas. Variables used were corrected count-rates for potassium, uranium, and thorium, total count, and the ratios 214Bi/40K, 214Bi/208Tl, and 208Tl/40K. Analysis showed that three factors were sufficient to represent all seven variables. Statistical groupings correspond reasonably well to the mapped formations in the area, but some patterns suggest geological complexities which do not appear on available maps. The analysis identifies unusual groupings that are unlike surrounding patterns; many of these occur over known oil and gas pools and appear to indicate geochemically abnormal ground. (author)