Giovanni Massa

A new FSA approach for in situ γ ray spectroscopy.

An increasing demand of environmental radioactivity monitoring comes both from the scientific community and from the society. This requires accurate, reliable and fast response preferably from portable radiation detectors. Thanks to recent improvements in the technology, γ spectroscopy with sodium iodide scintillators has been proved to be an excellent tool for in-situ measurements for the identification and quantitative determination of γ ray emitting radioisotopes, reducing time and costs. Both for geological and civil purposes not only (40)K, (238)U, and (232)Th have to be measured, but there is also a growing interest to determine the abundances of anthropic elements, like (137)Cs and (131)I, which are used to monitor the effect of nuclear accidents or other human activities. The Full Spectrum Analysis (FSA) approach has been chosen to analyze the γ spectra. The Non Negative Least Square (NNLS) and the energy calibration adjustment have been implemented in this method for the first time in order to correct the intrinsic problem related with the χ(2) minimization which could lead to artifacts and non physical results in the analysis. A new calibration procedure has been developed for the FSA method by using in situ γ spectra instead of calibration pad spectra. Finally, the new method has been validated by acquiring γ spectra with a 10.16 cm × 10.16 cm sodium iodide detector in 80 different sites in the Ombrone basin, in Tuscany. The results from the FSA method have been compared with the laboratory measurements by using HPGe detectors on soil samples collected particular, the (137)Cs isotopes has been implemented in the analysis since it has been found not negligible during the in-situ measurements.

A multivariate spatial interpolation of airborne γ-ray data using the geological constraints

In this paper we present maps of K, eU, and eTh abundances of Elba Island (Italy) obtained with a multivariate spatial interpolation of airborne γ-ray data using the constraints of the geologic map. The radiometric measurements were performed by a module of four NaI(Tl) crystals of 16 L mounted on an autogyro. We applied the collocated cokriging (CCoK) as a multivariate estimation method for interpolating the primary under-sampled airborne γ-ray data considering the well-sampled geological information as ancillary variables. A random number has been assigned to each of 73 geological formations identified in the geological map at scale 1:10,000. The non-dependency of the estimated results from the random numbering process has been tested for three distinct models. The experimental cross-semivariograms constructed for radioelement-geology couples show well-defined co-variability structures for both direct and crossed variograms. The high statistical correlations among K, eU, and eTh measurements are confirmed also by the same maximum distance of spatial autocorrelation. Combining the smoothing effects of probabilistic interpolator and the abrupt discontinuities of the geological map, the results show a distinct correlation between the geological formation and radioactivity content. The contour of Mt. Capanne pluton can be distinguished by high K, eU and eTh abundances, while different degrees of radioactivity content identify the tectonic units. A clear anomaly of high K content in the Mt. Calamita promontory confirms the presence of felsic dykes and hydrothermal veins not reported in our geological map. Although we assign a unique number to each geological formation, the method shows that the internal variability of the radiometric data is not biased by the multivariate interpolation.

The Miocene successions of the Fiora Hills: considerations about the development of the minor basins of Southern Tuscany

The Miocene sequences of Southern Tuscany represent the first post-nappe sedimentary record of the Northern Apennines, and are linked with the opening of the Tyrrhenian Sea. The sequences are located in several basins, characterizing the hinterland of the orogen. They are settled on a stack that is composed of deformed tectonic units and are capped by Plio-Pleistocene deposits. The respective basins have been strongly controlled by tectonics, which have remarkably forced the sedimentation. The Fiora Hills represent the southernmost area of Tuscany, where there are some minor but significant examples of these basins. In particular, they are the Fiora and the Tafone basins, the infillings of which are characterized by Miocene successions subdivided into several depositional units separated by unconformity or correlative conformity surfaces. This study deals with the stratigraphic features of such Miocene basinal infillings, with the aim being to define the depositional architecture and the tectonic-sedimentation interplays. Moreover, the collected data also enables there to be a discussion of some of the aspects of the basins’ structuring that are linked with the Miocene evolution of the hinterland of the Northern Apennines. The entire Miocene succession of the Fiora Hills spans from the Langhian up to the late Messinian, with there being minor differences between the Fiora-Tafone basins and with the nearby Albegna Basin. In general, we recognize: the basal Ponsano P Unit (middle Miocene), which is referable to coastal-shallow marine environment; the Lignitiferous T Unit (late Tortonian-early Messinian), which is referable to fan-delta and lacustrine systems; the Acquabona-Spicchiaiola M1 Unit (early Messinian), which is referable to lagoonal fan-deltaic environment; the Castelnuovo M2 Unit (early Messinian), which is referable to shallow marine environment; and the “Lago-Mare” M3 Unit (late Messinian), which is referable to fan-deltaic lacustrine systems. The Miocene succession is overlaid by Plio-Pleistocene marine to continental succession. The Miocene basins have settled on deformed Ligurian allochthonous units, which are markedly structured in tectonic depressions and highs and coherently so with the “crustal lateral segmentation” model. The development of the Miocene sedimentation in this sector of the chain appears to be strictly connected to the tectonic evolution of the Tyrrhenian Sea rifting. The middle Miocene deposits may in fact be related to the first syn-rift shallow-marine basins, marking the beginning of the post-nappe phase. During late Tortonian-early Messinian, important lacustrine-fan-delta systems dominated in the basins and represented the development of the middle Miocene stages. They evolved during the early Messinian in lagoonal fan-deltaic systems and then in shallow-marine systems. The transition to the upper Messinian deposits is marked by a significant unconformity, which is marked locally by angularity, thus noting an intramessinian deformative episode. This characterizes the lacustrine fan-deltaic systems that are linked to the Messinian salinity crisis for the paleo-Mediterranean Sea. The stratigraphic differences between the Fiora Hills’ basins are therefore linked to the somewhat different basinal sedimentary evolution, which is connected to the development of morphological/tectonic ridges.

First characterisation of natural radioactivity in building materials manufactured in Albania

This study focuses on the radiological characterisation of building materials manufactured in Albania by using a high-resolution gamma-ray spectrometer. The average activity concentrations of (40)K, (226)Ra and (232)Th were, respectively, 644.1±64.2, 33.4 ± 6.4 and 42.2 ± 7.6 Bq kg(-1) in the clay brick samples and 179.7 ± 48.9, 55.0 ± 5.8 and 17.0 ± 3.3 Bq kg(-1) in the cement samples. The calculated activity concentration index (ACI), varied from 0.48±0.02 to 0.63±0.04 in the clay brick samples and from 0.29±0.03 to 0.37±0.02 in the cement samples. Based on the ACI, all of the clay brick and cement samples were categorised as A1 materials. The authors can exclude (at 3σ level) any restriction of their use as bulk materials.

Total natural radioactivity, Tuscany, Italy

In this paper, we report an extensive survey of the natural radioactive content of rocks of the Tuscany Region (Italy): this permitted the first total natural radioactivity map of the region. The sampling was planned using the geological map of Tuscany at scale 1:250,000, which contains 45 distinct geological groups recognized by tectonic and stratigraphic features. Each geological group was characterized for the total activity by measuring the activity concentrations of 40K, 238U and 232Th in 865 samples using a high-purity germanium (HPGe) gamma-ray spectrometer. The average areal distribution of samples is approximately one sample per 25 km2. The radiometric map was constructed through the reclassification of each geological formation based on the median value of the total activity. Seven classes of total activity are identified by choosing percentiles almost evenly spread across the range of values. This map represents the starting point for future studies on natural background radiation, geochemical processes and epidemiological investigations.

Ligurian-derived olistostrome in the Pseudomacigno Formation of the Stazzema Zone (Alpi Apuane, Italy). Geological implications at regional scale

In the Stazzema Zone (southern part of the Alpi Apuane tectonic window) an olistostrome of kilometric extent (here informally called Ricavo olistostrome) incorporating blocks and slides of Lower Cretaceous limestones referable to the “Argille a Palombini” Formation of the Internal Ligurian Units forms a well-defined lens-shaped body in the upper portion of the Pseudomacigno Formation. The Pseudomacigno Formation is an Oligo-Miocene siliciclastic foredeep deposit making up the upper portion the Alpi Apuane metamorphic sequence. In spite of the greenschist metamorphic imprint of the sequence, the exotic limestones included in the olistostrome have locally escaped recrystallization so that their primary depositional texture and microfossil content are still recognizable. The microfacies of these limestones are represented by mudstones/wackestones with abundant calcitized radiolarians and sponge spicules associated with rare calpionellids and some planktonic forams indicative of the Valanginian. The occurrence of exotic materials derived from the Internal Ligurian Units in the Pseudomacigno Formation is consistent with the current model of forward migration of the thrust belt-foredeep system in the Northern Apennines according to which the tectonic transport of the Ligurian/Subligurian Nappes was accompanied by the emplacement of olistostromes in the flysch deposits. The presence of an olistostrome derived from the Ligurian Nappes in the Pseudomacigno Formation contributes in a roundabout way to highlight some contradictions existing between the 27 Ma age of metamorphism of the Alpi Apuane Unit obtained from radiometric measurements, widely accepted in the literature, and the regional paleogeographic model currently adopted by the Apennine geologists. The mere presence of Ligurian-derived materials in the Pseudomacigno Formation, in fact, establishes new constraints that make a 27 Ma age of the metamorphic peak incompatible with the paleogeographic reconstruction of the Northern Apennines that relocates the domain of the metamorphic Tuscan Units east of the original domain of the Tuscan Nappe. Following this restoration, ages of metamorphism not older than 13–14 Ma would be expected.

Geological 3D modeling for excavation activity in an underground marble quarry in the Apuan Alps (Italy)

The three-dimensional laser scanning technique has recently become common in diverse working environments. Even in geology, where further development is needed, this technique is increasingly useful in tackling various problems such as stability investigations or geological and geotechnical monitoring. Three-dimensional laser scanning supplies detailed and complete geometrical information in short working times, as a result of the acquisition of a large number of data-points that accurately model the detected surfaces. Moreover, it is possible to combine these data with high quality photographic images so as to provide important information for geological applications, as follows. A working approach, that combines terrestrial laser scanning and traditional geological surveys, is presented. A three-dimensional model, that includes information about the geological structure in an underground quarry in the Apuan Alps, is realized. This procedure is adaptable to other geological contexts, and because of its operating speed and accuracy it is invaluable for optimal excavation, in which a proper planning of quarrying activity is vital for safety and commercial reasons.

Mapping the natural radioactivity of Elba Island by means of geostatistical interpolation of airborne gamma-ray data.

Automated !-ray spectrometer for monitoring wastes made by nonnuclear industries XHIXHA G.1, BEZZON G.P.1, BROGGINI C.2, BUSO G.P.1, CACIOLLI A.2, CALLEGARI I.3, COLONNA T.3, FIORENTINI G.1, GUASTALDI E.3, KACELI XHIXHA M.4, MANTOVANI F.5, MASSA G.3, MENEGAZZO R.2, MOU L.1 ROSSI ALVAREZ AND C.2 AND STRATI V.5 1Legnaro National Laboratory (LNL-INFN), Via dell’Universita, 2 35020 Legnaro, Padova, Italy – (xhixha@fe.infn.it) 2Padova Section INFN, Via Marzolo 8 35131 Padova, Italy – (carlo.broggini@pd.infn.it ) 3CGT Center for GeoTechnologies, University of Siena, Via Vetri Vecchi, 34 52027 S. GiovanniValdarno, Italy – ()callegari@unisi.it 4University of Sassari, Botanical, Ecological and Geological Sciences Department, Piazza Universita 2107100 Sassari, Italy – (mxhixha@fe.infn.it ) 5University of Ferrara, Physics Department, Via Saragat, 1 44100 Ferrara, Italy – (mantovani@fe.infn.it )