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

• Tipo: Artigo em Revista Científica Internacional
• Data: 2017

Autores

Lamas, R (Autor) Outra; Miranda, MM (Autor) Outra; Pereira, AJSC (Autor) Outra; Neves, LJPF (Autor) Outra; Ferreira, N (Autor) Outra; Rodrigues, NV (Autor) Outra

Revista

Título: Journal Of Iberian Geology

Vol. 43

Páginas: 3-12

ISSN: 1698-6180

Editora: Springer Nature

Indexação

ISI Web of Knowledge - 1 Citação

Scopus - 3 Citações

Outras Informações

ID Authenticus: P-00N-E5Z

DOI: 10.1007/s41513-017-0001-y

Abstract (EN): Purpose 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. Methods For that, a total of 314 samples collected in the surface as well as in the subsurface were analysed by gamma-ray spectrometry techniques. Results 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 postorogenic/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. Conclusions Based on the results, it can be concluded that the late-to post-tectonic porphyritic, biotite or biotitemuscovite 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.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 10