## 4 Conclusions  
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. Field measurements were acquired to determine the radon radiation in the soil air and the gas permeability of soils in the area of the Chidvinskaya pipe.  
We showed that the highest values of radon radiation are at the border of the pipe with the host sediments. This is likely due to the fact that fractured fault zones with increased gas permeability are developed at the exocontacts of the pipe, leading to the formation of the observed anomalous radon radiation in the soil air. At the same time, the large thickness of the overlying layer can reduce the radon flux to the surface of the earth. A comparison of the distribution of radon radiation with the distribution of the gas permeability parameter showed that areas with increased radon radiation and gas permeability partially coincided, which could be associated with an increased thickness of the overlying sediments, as well as their composition.  
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: kimberlite, country rocks, and sandstones with siltstone interlayers of Ediacaran sedimentary rocks. The results of the calculations show that the rocks of the exocontacts of the pipe had the greatest potential for increased radon radiation. The calculated values of the radon radiation produced by these rocks exceeded 900 Bq\(\cdot\)m\({}^{-3}\) at equilibrium. The maximum radon radiation of these rocks could, however, reach 50-100 kBq\(\cdot\)m\({}^{-3}\). The least amount of radon was produced by the diatreme kimberlite. It was established that pipe lithology exocontacts were the source of the increased values of radon radiation observed in the soil air. The results obtained allow us to recommend the emanation method as an additional method for the search for kimberlite pipes or for mineral exploration. This method in  
Figure 5: Diffusion distribution of radon radiation in in the studied rock profiles.  
combination with gamma-spectrometric, seismometric, and magnetometric methods has high potential for application in geology and geophysics. Its advantages are ease of use and low cost, as drilling into the bedrock is not required.  
All authors contributed to the study conception and design. Conceptualization, validation, and writing--original draft preparation: E.Y. and A.P. Methodology: E.Y. and A.P. Formal analysis and investigation: E.Y. and A.P. Writing--review and editing: E.Y. and A.P. Funding acquisition: E.Y. Project administration and resources: E.Y. Supervision and visualization: E.Y. All authors have read and agreed to the published version of the manuscript.  
The reported study was funded by RFBR, project number 20-35-70060.  
Not applicable.  
The datasets presented in this study can be obtained upon request to the corresponding author.  
This work was supported by RFBR according to the project No 20-35-70060 \"Investigations of the conditions for increased radon emanation in the sedimentary cover of areas of kimberlite magmatism (on example the Arkhangelsk diamondiferous province)\".  
The authors declare that they have no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample_ID**} & \multicolumn{2}{c}{**Geographic Coordinates**} & \multicolumn{2}{c}{**Radon Radiation,**} & \multicolumn{1}{c}{**Gas Permeability,**} \\ \cline{2-5}  & **Longitude** & **Latitude** & **Bq\(\cdot\)m\({}^{-3}\)** & **m\({}^{2}\)** \\ \hline ChD-29 & 41.11525 & 64.94878 & \(1606\pm 489\) & 5.5 \\ ChD-30 & 41.11536 & 64.954