Geological mapping by spectrometry: a case study from Hungary

What is it about?

The Bagolyhegy Metarhyolite Formation of the Bükk Mts. (Hungary) hosts silicified rock bodies with high potassic feldspar content. As the outcrop area is covered by soil and debris, geological mapping was supported by a spectral gamma ray survey with a scintillation detector. A thunderstorm felling the forest made the soil horizon B also accessible in several pits. Measurements in different arrangements were designed to test the effects of measuring time, measuring geometry and soil horizon. Our results show that concentration values obtained on the debris with a 2 min measuring time can be compared with those measured on exposed rock surfaces. The survey successfully delineated the unexposed outcrop of K-enriched rocks on the survey area.

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Why is it important?

In this case study a survey protocol was tested and established for forest covered outcrop area of low grade metamorphic rocks. The anomalies of radioactive element contents may indicate rock alterations, which sometimes cannot be seen even on exposed rock surfaces, but which can show the proximity of ore bodies.