Airborne gamma-radiation survey of the Jabel Ishmas Quadrangle, Kingdom of Saudi Arabia

An airborne gamma-radiation survey system, which includes digital recording and automatic data processing procedures developed by the U. S. Geological Survey Saudi Arabian Project, is used to collect spectral gamma-radiation data as an aid to regional geologic mapping of pediment areas on the Arabian Shield. The areal extent of rock units can generally be distinguished by the intensity of their radiation pattern. Rocks of ultramafic composition have low radiation response, whereas more felsic rocks reflect higher radiation response.

Interpretations based on radiometric data enable the geologist to gain some understanding about the geologic setting of an area before he begins field mapping.