Natural gamma-radiation in the Aeolian volcanic arc.

Abstract

Pulse-height distributions of gamma-rays, obtained with a field NaI(Tl) scintillation spectrometer in numerous sites of the Lipari and Vulcano islands (Aeolian volcanic arc, Italy), were measured to determine the U, Th and K concentrations of the bedrock and the relative values of the air absorbed dose rate. U is spatially related to both Th and K and the Th/U ratio is on average 3.1-3.5. The magmatic evolution is reflected by the concentration of the three radioelements, as they are more abundant within the more felsic units of the volcanic series. The higher values of U (15.7-20.0 ppm) coincide with higher Th (48.3-65.9 ppm) and K (4.9-6.1%) concentrations associated with rhyolitic rocks of the third cycle (< 50 ky). The air absorbed dose rate varies from 20 to 470 nGy h(-1). The highest values (> 350 nGy h(-1)) are observed on outcrops of rhyolitic obsidian lava flows. The cosmic-ray contribution is also evaluated to estimate the total background radiation dose rate.

• Authors: P Chiozzi, V Pasquale, M Verdoya, S Minato
• Journal: Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine (Appl Radiat Isot) Vol. 55 Issue 5 Pg. 737-44 (Nov 2001) ISSN: 0969-8043 [Print] England
• PMID: 11573810 (Publication Type: Journal Article)