UDC

540.4+553.81

Authors

Yakovlev Evgeniy Yur’evich
Institute of Ecological Problems of the North, Ural Branch of the Russian Academy of Sciences
Naberezhnaya Severnoy Dviny, 109, Arkhangelsk, 163000, Russian Federation;
e-mail: yakovlev_eu@inbox.ru
Kiselev Georgiy Petrovich
Institute of Ecological Problems of the North, Ural Branch of the Russian Academy of Sciences
Naberezhnaya Severnoy Dviny, 109, Arkhangelsk, 163000, Russian Federation;
e-mail: kiselevgp@yandex.ru
Druzhinin Sergey Valerievich
Institute of Ecological Problems of the North, Ural Branch of the Russian Academy of Sciences
Naberezhnaya Severnoy Dviny, 109, Arkhangelsk, 163000, Russian Federation;
e-mail: druzhininserg@yandex.ru

Abstract

The currently problems in the use of traditional methods of forecasting and prospecting of diamond deposits in Arkhangelsk region, associated with a contrast reduction of allocated anomalies, necessitate to find other approaches to solve these problems. The identification of the wallrock alteration features of host sediments in core of exploration wells is actively developed in recent years. These host sediments are related to the impact of kimberlites, such as tectonic deformation, near-contact rock alteration, increased concentrations of radiation defects. An increase in intensity of rocks gamma radiation, concentrations of a number of radioactive elements such as uranium-238, thorium-232, potassium-40, and an increase of non-equilibrium of even uranium isotopes activities, which is the tracer interaction of ore matter and host sediments are also observed in the contact zone. In this regard, the study of the characteristics of the uranium isotopes fractionation in the solid phase of the near-contact zone on the example of a number of kimberlite pipes of the Lomonosov deposit comes at an opportune time. We studied the isotopic composition of uranium in kimberlites and host sediments of the Pionerskaya pipe of the Zolotitsa field of Arkhangelsk diamond province. The equilibrium isotopic composition of uranium in the diatreme kimberlites and host sediments remoted from the pipe is preferably retained. At the same time, the increase in the non-equilibrium of alpha activity of the uranium isotope pair in the solid phase of rocks in the near-contact zone of kimberlite is marked. This is a consequence of the interaction of kimberlite matter and host sediments, leading to the fractionation of even uranium isotopes.

Keywords

uranium isotopes fractionation, kimberlites, host sediments, contact zone, alpha activity, 234U/238U, Arkhangelsk diamond province

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