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Coltorti, Mauro
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Coltorti, Mauro
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- PublicationOpen AccessPotential dust sources for loess deposits in Central Italy: A geochemical case study from the Loess-Paleosol-Sequence of Ponte Crispiero (Marche)(2023)
; ; ; ; ; ; ; ; ;; ; ; ; ;; Identifying potential dust sources of Loess-Paleosol-Sequences (LPS) is important to understand past climatic and environmental conditions. For loess deposits of Central Italy different hypothesis on particle sources have been proposed, but none of them has been tested using a comprehensive geochemical approach yet. Here we present geochemical, mineralogical and grain-size data from selected deposits of a LPS situated at Ponte Crispiero (Marche, Central Italy) to obtain first insights on the provenance of particles deposited here. Loess deposits within the Ponte Crispiero succession are rather coarse (mostly coarse silt and fine sand) indicating a dominance of proximal dust sources. Applied geochemical indices suggest the alluvial plains of the Po River (Northern Italy) and its discharging area as major particle sources. According to these findings, the so-called “Great Po Plain” hypothesis, that claims the presence of a vast alluvial landscape related to the sea-level drop of the Adriatic Sea during the Pleniglacial (i.e. Marine Isotope Stage MIS 4–2), may be considered as a realistic scenario. Such a considerable alluvial plain would have the potential as major source for silt and sand particles not only for the Ponte Crispiero LPS, but also for the loess on the Adriatic side of Central Italy. The main geochemical characteristics of Ponte Crispiero loess are the low concentrations of Zr and Hf and the high contents of carbonate and transition elements compared to the Upper Continental Crust and other European loess sections. Overall, this study contributes towards a better understanding of the provenance and origin of Italian loess. However, for further testing the “Great Po Plain” hypothesis, more (geochemical) investigations need to be conducted, especially in the surrounding areas of the Po plain.62 12 - PublicationOpen AccessGeophysical and geotechnical observations to assess the morphological risk in the Acqua Albule Basin sinkhole prone area (Rome, Italy): two case studies(2016-09)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We present the results of multidisciplinary investigations of two significant sites, located in the Acque Albule Basin (AAB), 25 km Northeast of Rome (Italy). This basin has been interpreted as a transtensional structure, lying in the western margin of the Apennine range and affecting the Plio-Pleistocene sedimentary and volcanic sequences. During late Pleistocene times, AAB has been filled in with thermogenic travertine of variable thickness. Since historical time, lithoid travertine has been quarried, becoming the main building material during the Roman period (Lapis Tiburtinus). At present, the mining activity still represents the main economic resource of the region together with thermal baths. After the end of the II World War this area has experienced a strong urbanization and marshy lands were transformed into densely populated areas affected by subsidence and sinkhole phenomena. In order to characterize these environmental hazards from the geophysical and geotechnical point of view, we chose two test sites close to relevant anthropic infrastructures. Site A, located at the southern side of the Guidonia military airport and beside an important road; site B, a few kilometers South-East of site A, lies next to the Regina and Colonnelle Lakes and close to the Roma- Pescara railway. The former feature is a large sinkhole depression, hundreds of meters in width, characterized by ongoing subsidence, whereas the latter consists of two sinkholes actually acting as springs. Both sites lie in proximity of inferred faults, which would affect the AAB in the N-S and NE-SW– directions respectively. The aim of this study is to compare the two cases by collecting geological, geomorphological and geophysical parameters and thus testing the variable controlling their formation and development. We also extended the geophysical campaign in the surrounding area using a multidisciplinary approach to image both surface and subsurface features. We carried out stratigraphic and geomorphological survey, 2 and 3D Geoelectrical Tomography (ERT), differential GPS altimetry, gravity, magnetic, seismic, and soil gas measurements. Moreover, two drillings have been bored inside and outside the depression area of the Site A, reaching depths of 60 and 20 meter, respectively. Geotechnical parameters of the recovered stratigraphy were also measured by laboratory tests. In general, the approach we propose could provide key elements to recognize similar situations in sinkhole prone areas. Moreover, comparative analysis together with the monitoring of the A site can represent useful tools to understand the genesis and dynamics of phenomena and hopefully to forecast their evolution, particularly in the parts of the basin where active movements caused fractures and damages to buildings and infrastructures.92 31 - PublicationRestrictedGeochemical and geoelectrical characterization of the Terre Calde di Medolla (Emilia-Romagna, northern Italy) and relations with 2012 seismic sequence(2021)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Soil gas and Electrical Resistivity Tomography (ERT) surveys were performed in Medolla (Emilia-Romagna Region, northern Italy) within a farming area characterized by macroseeps, absence of vegetation and anomalous temperatures of soil to investigate the soil gas migration mechanism and verify the presence of a buried fault intersecting the macroseeps. Soil gas (222Rn, 220Rn, He and C2H6) concentrations and flux (φCO2 and φCH4) measurements were carried out from 2008 to 2015, comprising the 2012 Emilia seismic sequence. Moreover, in 2016 a ERT survey, combined with new flux measurements, was performed along four profiles (ranging from 180 to 630 m long) centered on the main macroseep. We found that the seismic sequence sensibly influenced the soil gas distribution in the area. All investigated species, but He, increased their values early after the mainshocks, likely due to crustal deformation which promoted the geogas uprising. In 2015, when the stress has vanished, these concentrations gradually decreased toward pre-seismic values. Helium concentrations showed an opposite behavior as they decreased in May 2012 and then gradually increased over time. This trend may be reasonably due to the enhancement of the strain field which promoted the He dissipation from soil to the atmosphere, due to its high volatility. In all the geochemical surveys conducted from 2008 to 2015, soil gas high values around the main macroseeps were identified, delighting the presence of an alignment in the E-W direction. This trend, identified for several gas species, ultimately supports the theory of a hidden fault which favors the intensification of fluids migration along zones characterized by greater permeability. ERT results highlighted a sub-horizontal layering characterized by different resistivity intervals, roughly matching local stratigraphy. In most profiles we observed a slightly increase of resistivity and a sharp inter-ruption of the electro-layering in correspondence of the main macroseep, both near the surface and at depth. This implies that a fracture zone due to the presence of a buried fault cannot be excluded. The combined use of geochemical and geophysical techniques in this study confirmed the usefulness of such multiparametric approach for mapping out hidden structures in tectonically active areas, allowing to better understanding the fluid migration processes through preferential leakage pathways.1243 3 - PublicationOpen AccessMultidisciplinary Study of Subsidence and Sinkhole Occurrences in the Acque Albule Basin (Roma, Italy)(2020)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; We present the results of a combined analysis of remote sensing and geophysical ‐ geotechnical data carried out in the Acque Albule Basin, a sinkhole prone area located close to the city of Roma, where a wide travertine wedge is present. We carried out geophysical measurements and borehole drillings over two test areas to image the subsoil where paroxysmal sur fi cial dynamics occur. One site is marked by subsidence occurring at least since the early 2000s, whereas the other site hosts the “ La Regina ” and “ Colonnelle ” sinkhole lakes, which discharge sulfur ‐ carbonated waters. The stability of these two sites threatens highway, railway, and airport facilities, and this study helps to assess the geological hazard. For example, InSAR and LiDAR data helped de fi ne wide scale subsidence over the last 20 years and previously undetected small ‐ scale morphologies. Geophysical measurements of the latter revealed shallow and deep dissolution affecting the travertine and driving sur fi cial paroxysmal events. Both study sites were found to lie inside a large depression located at the junction between Jurassic carbonate and Plio ‐ Pleistocene units in association with paleo karst morphologies in the travertine deposits and affected by the present ‐ past spillage of sulfurous waters. Given these elements, multidisciplinary geophysical observations are crucial for assessing and mitigating the geological risk and guiding land use planning and management.866 48