Airborne Radiometric Surveying Explained

Airborne Radiometric Surveys

Radiometric Surveys detect and map gamma rays, and can be performed on the ground, in the air, or in a borehole.  Airborne gamma-ray spectrometry or radiometric surveying for mineral exploration measures the gamma-rays that are emitted from naturally occurring radioactive isotopes that are found in rocks and soils near the surface.  The most abundant of these radioactive isotopes are potassium (K40), uranium (U238), and thorium (Th232).    
A gamma-ray spectrometer is the device used for measuring the distribution and intensity of gamma ray radiation.  Typically used in airborne radiometric surveying are RS-500 spectrometers manufactured by Radiation Solutions Inc.  These are recognized as the most advanced airborne spectrometer systems available, and include an on-board computer which allows real-time signal processing analysis, automatic gain control for individual crystals, multi-channel analysis and full spectrum recording.


The usefulness of airborne radiometric surveys for mineral exploration and geological mapping depends on the following:


1. the measured radioactive isotope distributions relate to different lithologies in the bedrock (normal litholigic signatures)


2. normal lithologic signatures are distinctly modified by mineralizing processes (alteration zones)


3. bedrock signatures migrate into surficial materials (exposed bedrock, sediments, affected by soil and vegetation types, and surface water)


4. surficial materials can be spatially related to bedrock sources


Applications of Airborne Radiometric Surveys


1. Prospecting for Economic Minerals

·         exploration for uranium deposits

·         direct detection of uranium at surface

·         exploration for porphyry copper deposits where potassic alteration gives rise to a radiometric signature

·         exploration for gold using the Au-U association

·         exploration for radioactive haloes over hydrocarbon deposits


2. Geological Mapping

·         litholigic mapping at surface


3. Engineering and Hazard Studies

·         monitoring radioactive leakage from nuclear power plants


Specialists in Radiometric Surveys

Terraquest was established in 1984 and since then, our dedicated team has flown over 1,500 airborne geophysical surveys using both fixed wing and helicopter platforms.  Our professional crews provide significant experience having carried out airborne magnetic, gravity, gamma ray spectrometry, and electromagnetics on five continents.  Our quality data sets have been utilized in the exploration for base and precious metals, kimberlite, hydrocarbons, uranium, rare earth minerals and water. The company has performed exemplary surveys for both small and large exploration groups as well as many government agencies.  References can be provided upon request.  Visit



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