## 4 Conclusions  
Experimental studies 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 this purpose, samples of kimberlites and rocks were taken from the quarries of the Arkhangelskaya and Karpinsky-1 pipes of the Lomonosov diamond deposit. The samples were represented by the main types of rocks exposed by quarries to a depth of 186 m: overlying Quaternary (Q) and Carboniferous rocks (C\({}_{2}\)), host rocks of the Verdian (V\({}_{2}\)), tuffaceous-sedimentary rocks of the crater (iD\({}_{3}\)-C\({}_{2}\)) and kimberlites of the vent facies (iD\({}_{3}\)-C\({}_{2}\)).  
Radiation (activity of \({}^{226}\)Ra, activity of \({}^{222}\)Rn in a free state, emanation coefficient, radon production rate) and physical (average and true density, porosity) parameters were determined.  
Among the studied types of rocks, it was found that kimberlites of the vent facies are characterized by the lowest values of the emanation coefficient, porosity, specific activity of \({}^{226}\)Ra and the radon production rate. The lowest values of these parameters limit the formation of free radon in the pipe body.  
The largest amount of radon in a free gas state has been produced by rocks of the near-pipe space, represented by the enclosing Verdian V\({}_{2}\) deposits and characterized by high values of the emanation coefficient, specific activity of radium, radon production rate and porosity. This is due to the structural and geological features of the near-pipe space, which has signs of the impact of kimberlite magma on the host rocks: the development of fracturing as well as structural, mineralogical and geochemical changes. The overlying and tuffaceous-sedimentary rocks of the crater are characterized by intermediate values of the studied parameters.  
This study advances the knowledge of using emanation methods for prospecting for kimberlite pipes in the territory of the Arkhangelsk diamondiferous province.  
Figure 7: Regression model of the relationship between the volumetric activity of radon and the level of radon production.  
**Author Contributions:** All authors contributed to the study conception and design. Conceptualization, validation, and writing--original draft preparation were performed by E.Y. and A.P. Methodology was performed by E.Y. and A.P. Formal analysis and investigation were performed by E.Y. and A.P. Writing--review and editing were performed by E.Y. and A.P. Funding acquisition were performed by E.Y. Project administration and resources were performed by E.Y. Supervision and visualization were performed by E.Y. All authors have read and agreed to the published version of the manuscript.  
**Funding:** The reported study was funded by RFBR, project number 20-35-70060.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The datasets presented in this study can be obtained upon request to the corresponding author.  
**Acknowledgments:** The authors are grateful to the staff of the Laboratory of Environmental Radiology of N. Laverov Federal Center for Integrated Arctic Research for their invaluable help and support at all stages of the study.  
**Conflicts of Interest:** The authors declare that they have no conflicts of interest.  
Appendix C Typical Types of the Studied Rocks from the Lomonosov Diamond DepositFigure 16: Red sandstone (sample ID 24 CA_13), Vendian enclosing rocks of the near-pipe space (\(V_{2}\)), Arkhangelskaya pipe.