Radon over Kimberlite Pipes: Surface Field Experiments and Calculations of Vertical Diffusion (Arkhangelsk Diamondiferous Province, NW Russia)

Evgeny Yakovlev,Andrey Puchkov

doi:10.3390/app112411765

Abstract

We present the results of field and experimental studies to assess the influence on the formation of the radon field over the kimberlite pipes of the Arkhangelsk diamondiferous province. Measurements were made in the field to establish the radon radiation in the soil air and the gas permeability of soils in the area of the Chidvinskaya pipe. Experimental work was aimed at determining the radiation and physical parameters of the rocks occurring within the kimberlite field. Based on a set of field and experimental data, a model of the diffusion transfer of radon in the area of the Chidvinskaya pipe was calculated for three profiles, represented by the rocks of the pipe, sedimentary rocks of the exocontacts of the pipe, and host sandy and clay sedimentary rocks. The results of the calculations show that the rocks of the exocontacts of the pipe have the greatest potential for increased radon radiation. The calculated values of the radon radiation produced by these rocks exceeded 9000 Bq·m−3. The diatreme kimberlites produced the lowest radon radiation. We showed that the source of the increased values of radon radiation is the rocks of the pipe’s exocontacts. This fact will make it possible to use the emanation method as an additional one for the search for kimberlite pipes.

Highlights

The radon-222 isotope is constantly formed in almost all natural environments during the radioactive decay of its parent radium-226 isotope
This may be due to the fact that, at the contacts of the Chidvinskaya pipe with the host Ediacaran rocks, fractured fault zones with increased gas permeability are developed, leading to the formation of the observed positive anomalous radon radiation in the soil air
Using the example of the Chidvinskaya pipe, field and experimental studies were carried out to identify the main factors influencing the formation of the radon field over the kimberlite pipes of the Arkhangelsk diamondiferous province in order to develop emanation methods for the search for kimberlite pipes

Summary

Introduction

The radon-222 isotope is constantly formed in almost all natural environments during the radioactive decay of its parent radium-226 isotope. Radon is used as a tracer in its “free” state, which allows it to migrate freely in various media both in gaseous form and as a water-soluble compound [3,11,12,13]. This process leads to the appearance of an emanation field in the near-surface horizons of rocks, grounds, and soils [3,14,15]. The analysis of emanation fields is widely used in geochemical, geophysical, and geodynamic research [4], including the search for mineral deposits [16,17,18,19]

Objectives

Methods

Results

Conclusion