3-D distribution of the radioelements in the granitic rocks of northern and central Portugal and geothermal implications



The main purpose of this work is to study the distribution of radioelements in both horizontal and vertical directions within the main granitic units outcropping in northern and central Portugal in order to assess the main target for geothermal energy feasibility studies.


For that, a total of 314 samples collected in the surface as well as in the subsurface were analysed by gamma-ray spectrometry techniques.


The results show that the older granitic units studied (syn-orogenic pre-D3) reveal smaller concentrations of both uranium (U = 4.5 mg/kg) and thorium (Th = 9.1 mg/kg) than the youngest units (late- to post-orogenic/post-D3). This last group presents an average concentration of 7.1 mg/kg for uranium and 21.0 mg/kg for thorium. The subsurface samples belong to the youngest granitic group that was studied, and present higher uranium concentration (U = 14.3 mg/kg) but a decrease in thorium concentration (Th = 17.5 mg/kg) in comparison with the surface samples of the same lithology. Within 1000 m in depth the concentration of radioelements has a remarkably constant pattern suggesting that the distribution of radioelements is not a function of depth.


Based on the results, it can be concluded that the late- to post-tectonic porphyritic, biotite or biotite-muscovite granite (e.g., Beiras Granitic Batholith) is the highest radiothermal granitic group in the studied area, which makes it the main target for more detailed studies regarding its potential for geothermal energy, for power production and others exploitation options in Central Portugal.



El objetivo principal de este trabajo es estudiar la distribución de radioelementos tanto en dirección horizontal como vertical dentro de las principales unidades graníticas aflorantes en el norte y centro de Portugal para evaluar cuál de ellas tiene más potencial para estudios de viabilidad de energía geotérmica.


Para eso, un total de 314 muestras recogidas en la superficie así como en el subsuelo se analizaron mediante técnicas de espectrometría de rayos gamma.


Los resultados muestran que las unidades graníticas más antiguas estudiadas revelan concentraciones más bajas de ambos, uranio (U = 4,5 mg/kg) y torio (Th = 9,1 mg/kg) que las unidades más recientes. Este último grupo se presenta con una concentración media de 7,1 mg/kg de uranio y 21,0 mg/kg para el torio. Las muestras de subsuelo pertenecen al grupo granítico más reciente y presentan un aumento en la concentración de uranio (U = 14,3 mg/kg), pero una disminución de torio (Th = 17,5 mg/kg) en comparación con las muestras superficiales de la misma litología. Hasta los 1000 m de profundidad la concentración de radioelementos tiene un padrón notablemente constante lo que sugiere que la distribución de los radioelementos no es una función de la profundidad.


Con base en los resultados, se puede concluir que el granito profiroide, biotitico o biotitico-muscovitico tarde- a post-tectónico (e.g., Batolito Granítico das Beiras) es el grupo granítico más radiotérmico del área estudiada, lo que lo hace el principal objetivo de estudios más detallados sobre su potencial para la energía geotérmica, para la producción de energía y otras opciones de explotación en el centro de Portugal.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6


  1. Basham, I. R., & Matos Dias, J. M. (1986). Uranium veins in Portugal. In International Atomic Energy Agency (Ed.), Vein type uranium deposits (pp. 181–191). Austria: International Atomic Energy Agency Technical Document.

    Google Scholar 

  2. Boyle, R. W. (1982). Geochemical prospecting for thorium and uranium deposits. Amsterdam: Elsevier.

    Google Scholar 

  3. Cabral Pinto, M. M. S., Silva, M. M. V. G., & Neiva, A. M. R. (2014). Release, migration, sorption and (re)precipitation of U during a granite alteration under oxidizing conditions. Procedia Earth and Planetary Science, 8, 28–32.

    Article  Google Scholar 

  4. Chiozzi, P., Pasquale, V., & Verdoya, M. (2002). Heat from radioactive elements in young volcanics by γ-ray spectrometry. Journal of Volcanology and Geothermal Research, 119, 205–214.

    Article  Google Scholar 

  5. Clauser, C. (2006). Geothermal energy. In K. Heinlot (Ed.), Energy technologies, subvolume C: Renewable energy. Numerical data and functional relationships in science and technology, group VIII: Advanced materials and technologies volume 3 (pp. 493–604). Berlin: Landolt-Börnstein, Springer.

    Google Scholar 

  6. Dias, G., Leterrier, J., Mendes, A., Simões, P. P., & Bertrand, J. M. (1998). U–Pb zircon and monazite geochronology of post-collisional Hercynian granitoids from the Central Iberian Zone (Northern Portugal). Lithos, 45, 349–369.

    Article  Google Scholar 

  7. Ferreira, N., Iglesias, M., Noronha, F., Pereira, E., Ribeiro, A., & Ribeiro, M. L. (1987). Granitoides da Zona Centro Iberica e seu enquadramento geodinâmico. In F. Bea, A. Carnicero, J. C. Gonzalo, M. López Plaza, & M. D. Rodríguez Alonso (Eds.), Geologia de los granitoides y rocas associadas del Macizo Hesperico (pp. 37–51). Madrid: Editorial Rueda.

    Google Scholar 

  8. Ferreira, J. A., Ribeiro, M. A., & Martins, H. C. B. (2014). The Pedregal granite (Portugal): Petrographic and geochemical characterization of a peculiar granitoid. Estudios Geológicos, 70(2), 1–9.

    Article  Google Scholar 

  9. Godinho, M. M., Pereira, A. J. S. C., & Neves, L. J. P. F. (1991). Potencial térmico das rochas graníticas num segmento do Maciço Hespérico (Portugal Central). Memórias e Notícias, 112, 469–483. (Publ. Mus. Lab. Mineral. Geol Univ. Coimbra).

    Google Scholar 

  10. Jaupart, C., & Mareschal, J.-C. (2003). Constraints on crustal heat production from heat flow data. In R. Rudnick (Ed.), Treatise of geochemistry. The crust (Vol. 3, pp. 65–84). New York: Elsevier.

    Google Scholar 

  11. Jiménez-Díaz, A., Ruiz, J., Villaseca, C., Tejero, R., & Capote, R. (2012). The thermal state and strength of the lithosphere in the Spanish Central System and Tajo Basin from crustal heat production and thermal isostasy. Journal of Geodynamics, 58, 29–37.

    Article  Google Scholar 

  12. Lachenbruch, A. H. (1970). Crustal temperature and heat production: Implications of the linear heat-flow relation. Journal of Geophysical Research, 75, 3291–3300.

    Article  Google Scholar 

  13. LNEG. (2010). Carta Geológica de Portugal à escala 1:1000,000. ISBN: 978-989-675005-3.

  14. Martins, L., Gomes, E., Neves, L., Sousa, L., & Oliveira, A. (2010). Dados preliminares da radioactividade natural na região de Amarante (Norte de Portugal). VIII Congresso Nacional de Geologia, 13(14), 1–4.

    Google Scholar 

  15. Mateus, A., & Noronha, F. (2010). Sistemas mineralizantes epigenéticos na Zona Centro-Ibérica; expressão da estruturação orogénica Meso- a Tardi-Varisca. In J. M. Cotelo Neiva, A. Ribeiro, M. Victor, F. Noronha, & M. Ramalho (Eds.), Geologia Aplicada. Ciências Geológicas: Ensino, Investigação e sua História (Vol. 2, pp. 47–61). Porto: Universidade do Porto.

    Google Scholar 

  16. Pasquale, V., Verdoya, M., & Chiozzi, P. (2014). Geothermics: Heat flow in the lithosphere. Springer briefs in earth sciences. Berlin: Springer.

    Google Scholar 

  17. Pérez-Soba, C., Villaseca, C., Orejana, D., & Jeffries, T. (2014). Uranium-rich accessory minerals in the peraluminous and perphosphorous Belvís de Monroy pluton (Iberian Variscan belt). Contributions to Mineralogy and Petrology, 167(1008), 1–25.

    Google Scholar 

  18. Plant, J. A., Reeder, S., Salminem, R., Smith, D. B., Tarvainen, T., De Vivo, B., et al. (2003). The distribution of uranium over Europe: Geological and environmental significance. Applied Earth Sciences, 112, 221–238.

    Article  Google Scholar 

  19. Sams, M. S., & Thomas-Betts, A. (1988). 3-D numerical modelling of the conductive heat flow of SW England. Geophysical Journal, 92, 323–334.

    Article  Google Scholar 

  20. Stober, I., & Bucher, K. (2013). Geothermal energy: From theoretical models to exploration and development. Berlin: Springer.

    Google Scholar 

  21. Tammemagi, H. Y., & Smith, N. L. (1975). A radiogeologic study of the granites of SW. England. Journal of the Geological Society of London, 131, 415–427.

    Article  Google Scholar 

  22. Taylor, S. R., & McLennan, S. M. (1985). The continental crust: Its composition and evolution. Oxford: Blackwell Scientific Publishing.

    Google Scholar 

  23. Teixeira, R. J. S., Gomes, M. E. P., Martins, L. M. O., Pereira, A. J. S. C., & Neves, L. J. P. J. (2014). Natural radiation and geochemistry of the Lamas de Olo biotite granite, northern Portugal. Goldschmidt Abstracts, 2014, 2458.

    Google Scholar 

  24. Wheildon, J., Francis, M. F., Ellis, J. R. L., & Thomas-Betts, A. (1981). Investigation of the S.W. England thermal anomaly zone. Commission of the European Communities.

Download references


This work has been framed under the Initiative Energy for Sustainability of the University of Coimbra and supported by the Energy and Mobility for Sustainable Regions Project (CENTRO-07-0224-FEDER-002004), co-funded by the European Regional Development Fund (ERDF) through the «Programa Operacional Regional do Centro 2007–2013 (PORC)», in the framework of the «Sistema de Apoio a Entidades do Sistema Científico e Tecnológico Nacional», and by the «Fundação para a Ciência e Tecnologia». The authors would like to acknowledge Prof. José António Simões Cortez and Câmara Municipal de Almeida for allowing the study of the borehole core, and Jorge Carvalho e Inês Pereira for their help in improving the manuscript.

Author information



Corresponding author

Correspondence to M. M. Miranda.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lamas, R., Miranda, M.M., Pereira, A.J.S.C. et al. 3-D distribution of the radioelements in the granitic rocks of northern and central Portugal and geothermal implications. J Iber Geol 43, 3–12 (2017). https://doi.org/10.1007/s41513-017-0001-y

Download citation


  • Radioelements
  • Granites
  • Geothermal energy
  • Central Iberian Zone
  • Portugal

Palabras clave

  • Radioelementos
  • granitos
  • energía geotérmica
  • Zona Centroibérica
  • Portugal