RadiometricsThere are several types of geophysical surveys which can be used to better understand th

RadiometricsThere are several types of geophysical surveys which can be used to better understand the composition and physical properties of a landscape. One of the most important to our understanding or near-surface geology is the radiometric method. The radiometric process measures the gamma-ray activity of the radioelements potassium, thorium and uranium which the radioisotopes of these elements emit during radioactive decay. Airborne radiometric surveys are able to measure gamma radiation above the ground from either helicopters or low flying aircrafts.Changes in the concentrations of the three radioelements U, Th and K accompany most major changes in rock packages, hence the method can be used as an approximate mapping tool in many areas. However, in old weathered terranes where erosion rates are high, this method does not give an accurate approximation of the underlying lithologies.All of the rocks and soils on the Earth’s surface contain radioactive isotopes, and nearly all of the gamma-rays we can detected are the result of the natural decay of the radioisotopes uranium, thorium and potassium.Variations in radioelement concentrations may indicate primary processes such as mineralising solutions or metamorphic processes. These variations are also characterise secondary geological processes, like supergene alteration and leaching. Gamma rays can travel several hundred metres through the air, and through the first 35 centimetres of soil and rock at surface. Any detected gamma rays originate from the ground surface, not from depth. Since each gamma ray has a unique energy, the measurement of this energy allows us to differentiate between the three radioisotopes. Below is ternary image of the Radiometric Map of Australia, generated by producing ratios of the three radioelements U, Th and K.AHPSourcesbit.ly/1OOcHdqbit.ly/1n5AVDybit.ly/1n5AUQ3Imagebit.ly/1n5AVDy -- source link

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