ABSTRACT

Radiometric methods are included in the treatment of geophysical exploration techniques although, in general, they are based on the instrumental analysis of elemental contents in geological bodies, hence they too involve geochemical principles. Basically, two causes of radioactivity have to be considered: natural and anthropogenic. In the marine milieu the radiation to be considered will be electromagnetic (gamma radiation) or particular (neutrons). The most likely and most important form of radiation to be used in marine radiometric exploration tools is therefore electromagnetic, i.e., gamma radiation. For geophysical measurements directly on the sea floor, two media that may contain radioelements have to be considered: seawater and geological sea floor deposits. Radiometric surveying of sea floor deposits will be concentrated on marine sediments and outcropping rocks only. As regards the system testing incorporating neutron activation techniques directly on the ocean floor, the techniques to be applied are either normal instrumental neutron activation analysis or prompt gamma ray spectrometry.