A radiometric and petrographic interpretation of discrepancies on uranium content in samples collected at Alte Madonie Mounts region (Sicily, Italy) G. Lanzo a , S. Rizzo b , E. Tomarchio b, * a Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università degli Studi di Palermo (Italy), Via Archirafi, 26, 90123 Palermo, Italy b Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici (DEIM), Università degli Studi di Palermo (Italy), Viale delle Scienze, Edificio 6, 90128 Palermo, Italy article info Article history: Received 4 February 2013 Received in revised form 30 November 2013 Accepted 12 December 2013 Available online Keywords: Environmental radioactivity Radiation monitoring Gamma-ray spectrometry X-ray fluorescence X-ray diffractometry abstract The main goal of this work is to evaluate a correlation between anomalous Uranium (U) content and petrographic features of some soil and rock samples collected at Alte Madonie Mounts region (North- central Sicily, Italy). A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in “Marinelli” beakers for 20 days before the measurement to ensure that radioactive equilibrium between 226 Ra and 214 Bi was reached. Gamma-ray spectrometric analysis was used to quantify radio- activity concentrations. Mineralogical and chemical features of the samples were determined by X-ray Fluorescence (XRF), X-ray Diffractometry (XRD), Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) and Scanning Electron Microscope e Energy Dispersive Spectrometry (SEM-EDS) analyses. The average values of concentrations of 226 Ra, 228 Ac and 40 K were respectively 30, 17 and 227 Bq kg 1 while the greatest values were 134, 59 and 748 Bq kg 1 . Linear relationships were observed between 226 Ra, 228 Ac and 40 K concentrations: the activities of 226 Ra and 228 Ac were comparable, while those of 40 K were about 10 times greater. An exception was highlighted for a group of samples where 226 Ra activities were much higher than expectations. Chemical compositions and mineralogical features of the samples have made it possible to justify these anomalies. Ó 2013 Published by Elsevier Ltd. 1. Introduction A measurement campaign to investigate the natural radionu- clide content of rocks and soils collected in the area of “Alte Madonie” Mounts (North-central Sicily, Italy, Fig. 1) was carried out. The aim of this work was to correlate, whenever possible, natural radionuclide activity measurements both in soils and rocks with geological features. Few studies have addressed this issue (e.g. Isinkaye and Shitta, 2010; Abbaspour et al., 2010) although there are various works related to the natural radioactivity measure- ments by gamma-ray spectrometry only. Gamma-ray spectrometry is a valuable tool in the Earth Sciences; it is used for environmental and geological interpretations (Cannizzaro et al., 1994, 1995, 1999; 2004) and, in a wide prospective, gamma-ray spectroscopy pro- vides a very efficient marker for several geochemical processes (e.g., Lanzo et al., 2010). For these purposes we considered 32 rocks and 9 soils samples: carbonates (limestones, dolostones and marls), and siliciclastic rocks (clays, arenites and conglomerates) were selected. These lithologies represent the rocks, belonging to the main Mt. Madonie stratigraphic units (upper Trias to lower Miocene; Grasso et al., 1978), that crop-out with greater abundance and were sampled in order to assess the mean values of the envi- ronmental radioactivity of the whole Mt. Madonie area. The Madonie Mounts fall within the central sector of the northern Sicilian e Maghrebian thrust belt (Fig. 1: inset) and represent the result of the compressive tectonic regime (mainly with a southern vergence) that, between the early Miocene and the Lower Pliocene, was achieved through the overthrust of several Mesozoic paleogeographic domains (Nigro and Renda, 2000). The latter were characterized by wide successions of pelagic basin (Imerese Domain) and carbonate platform (Panormide Domain), and by a sequence of siliciclastic and terrigenous rocks (Numidian Flysch). During the development of the Neogene collisional systems other minor adjacent domains, characterized by marl limestone and pelitic units, were involved. * Corresponding author. Tel.: þ39 (0)91 232251, þ39 (0)91 23897366; fax: þ39 (0)91 232202. E-mail address: elio.tomarchio@unipa.it (E. Tomarchio). Contents lists available at ScienceDirect Journal of Environmental Radioactivity journal homepage: www.elsevier.com/locate/jenvrad 0265-931X/$ e see front matter Ó 2013 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.jenvrad.2013.12.008 Journal of Environmental Radioactivity 129 (2014) 73e79