R.S. Foote
C. M. Bunker
R.M. Moxham
1965
<p><span>The uranium, thorium, and potassium content of hydrothermally </span>altered<span> </span>rocks<span> in the vicinity of several copper and copper-lead-zinc deposits in Arizona was determined by chemical analysis. Potassium in the more intensely </span>altered<span> zones is about twice that in unaltered areas. There is no corresponding increase in thorium, so a higher potassium/thorium ratio also results from alteration; abnormally high uranium, locally in secular disequilibrium, was observed at the Bagdad porphyry copper deposit. A truck-mounted gammarray </span>spectrometer<span> was used to obtain a spectrum of </span>gamma<span> emission at each sample location. Equating the spectrometric with the chemical data gave standard errors of 0.6 percent potassium, 3 ppm thorium, and 10 ppm uranium for the outcrop analyses with the </span>spectrometer<span>. The amount of potassium introduced by hydrothermal alteration is thought sufficient in quantity to be detected by either surface or aerial spectrometry; spectrometric detection of anomalous uranium is probably marginal, owing to the disequilibrium. The potassium/thorium ratio may provide a means of distinguishing, in such surveys, between hydrothermally </span>altered<span> high-potassium zones and unaltered extrinsically high-potassium intrusives. </span></p>
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10.2113/gsecongeo.60.4.653
en
Society of Economic Geologists
Gamma-ray spectrometer studies of hydro-thermally altered rocks
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