Radiation and physical parameters of kimberlites and host rocks of the Lomonosov diamond deposit (Russian North-West)

Abstract

In this paper, experimental studies of rocks were carried out to assess the main radiation and physical factors affecting the formation of the radon field over the kimberlite pipes of the Arkhangelsk diamondiferous province (for example, the Lomonosov diamond deposit). For various types of rocks, the following was studied: porosity, density, radium-226 activity, free radon activity, radon production rate, emanation coefficient. The research results showed that the main factors in the formation of the radon field are porosity and the coefficient of emanation. These parameters directly affect the amount of free radon. In addition, we calculated the radon production by various types of rocks, represented by vent kimberlites, tuffaceous-sedimentary rocks of the crater, enclosing and overlying sediments. Regression analysis showed that the radon production rate in rocks reflects the formation of a radon field under conditions of occurrence of a kimberlite body. The studied radiation and physical parameters showed that the greatest amount of radon in a free state is produced by rocks of the near-pipe space, represented by the enclosing Vendian V2 deposits and characterized by high values of the emanation coefficient, specific activity of radium, the radon production rate, and porosity. At the same time, the formation of free radon in the tube body is limited due to the low values of porosity, emanation coefficient, and the radon production rate.