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Santo A.,University of Naples Federico II | Ascione A.,University of Naples Federico II | del Prete S.,Geologist | di Crescenzo G.,University of Naples Federico II | Santangelo N.,University of Naples Federico II
Acta Carsologica

This study focuses on karst collapse sinkholes of the southern and central Apennines region (Italy), and has the aim of outlining and discussing the factors which contribute to the occurrence of collapse phenomena. By the analysis of the morphometrical/morphological features of the about 600 initially identified sinkholes, about 50% were interpreted as collapse sinkholes related to karst phenomena, which are the object of this study. These were geo-referred and organised in a data base, in which information on the geological-structural and hydrogeological features of areas affected by the collapses was also reported. The collapse sinkhole inventory was paralleled by an analysis of the distribution of the main mineral springs (H2S- and CO2- rich waters), of travertine bodies and of extensional faults with late quaternary activity, which were all considered significant to the study due to the interrelations linking travertines, karst solution processes, CO2- rich waters and faults. Furthermore, with the aim of investigating the role of seismic shaking in the occurrence of the collapses, the karst collapse sinkhole distribution was compared with the distribution of stronger historical earthquake epicentres. The results of this regional scale synthesis suggests a possible key to the interpretation of karst collapse phenomena. The latter, in fact, appear correlated to the combination of peculiar conditions, which may be envisaged in the presence of active faults and mineral waters. The study, in particular, suggests that karst collapse sinkholes result from enhanced dissolution phenomena related to the rising of fluids of deep origin, for which active faults represent preferred pathways, and favoured by the presence of a relatively shallow water table. In the collapse events, an important role is possibly played by seismic shaking. Source

Allegrezza M.,Marche Polytechnic University | Ballelli S.,University of Camerino | Mentoni M.,Geologist | Olivieri M.,Marche Polytechnic University | And 3 more authors.
Plant Sociology

We present here a phytosociological study performed on the vegetation of 'Piè Vettore', which includes the southern slopes of Mount Vettore and Mount Vettoretto. These are the highest peaks of the mountain group of the Sibillini Mountain range (Central Apennines), within the National Park of 'Monti Sibillini', and included in two Natura 2000 areas. The great environmental variability and complexity that characterises the territory under investigation has resulted in great phytocoenotic diversity, as seen by the nine vegetational types detected here and updated with the latest nomenclature and syntaxonomic revisions. Five of these belong to habitats of European Community interest. These new associations are here proposed: Cerastio tomentosi-Seslerietum nitidae, Gentiano dinaricae-Globularietum meridionalis, Viburno lantanae-Ostryetum carpinifoliae, Sorbo ariae-Juniperetum nanae as well as numerous subassociations and syntaxa variants that have already been described but have not been reported for this mountain group. The intermixing of Mediterranean and montane-Mediterranean species that are typical of the mesotemperate bioclimatic belt with species of the supratemperate and orotemperate belt serve as a common thread in the characterisation of the floristic composition of different plant communities described. This intermixing is also linked to the southern exposure of the slopes, and is perhaps amplified by the ongoing climate change, thus contributing to the differentiation of a unique and original landscape. Moreover, during the sampling of the relevé data, rare species of phytogeographical interest were also found. Among these, Juniperus communis subsp. hemisphaerica detected for the first time in the Sibillini Mountain range, and according to our present knowledge, it has here its northernmost distribution limit along the Apennines. The results of this study have allowed us to broaden the floristic-vegetational knowledge of the National Park of Monti Sibillini, and they have also contributed to further definition the vegetational and landscape framework of a representative sector of this important Apennine district. As far as reforestation is concerned, which until now has been little investigated from the phytosociological point of view, the data obtained in this study provides important ecological information, and should provide the basis for silvicultural renaturation of the area. © Italian Society for Vegetation Science. Source

Tzamos E.,Aristotle University of Thessaloniki | Filippidis A.,Aristotle University of Thessaloniki | Rassios A.,Institute of Geology and Mineral Exploration | Grieco G.,University of Milan | And 6 more authors.
Journal of Geochemical Exploration

The concentration of major (Cr, Al, Mg, Fe) and minor (Ti, V, Mn, Ni, Zn) elements was studied in chromitite ores and accessory chrome spinels within serpentinite host rocks from the Xerolivado-Skoumtsa mine (Southern Vourinos, Western Macedonia, Greece) by means of electron microprobe techniques. Chrome ores in the mine occur in seven extensive ore bodies. Chromite was analyzed with respect to its position within or between ore bodies, including the following classifications: chromitite (schlieren ore) band, accessory chromite in intercalated serpentine within the ore bodies, disseminated chromite in non-ore bearing host rocks, and chromite within serpentinites intermediately adjacent to ore bodies. Chrome spinel originally forms at temperatures of around 1300 °C, but their hosts undergo ductile deformation to temperatures down to around 700 °C, thus facilitating solid state re-equilibration. Results showed that Mg in chromite was found to be substituted during re-equilibration mainly by Fe and, to a minor extent, by Mn and Zn. Cr is mainly substituted by Al and, to a minor extent, V. Compositions were found to vary in accessory chromite crystals as a function of their distance from chromitite bands. Specifically, the average concentrations of Cr and Mg are higher in spinels within chromitite ores than for the disseminated spinels in serpentine gangue layers within chromitites. Chrome spinels in schlieren ore layers have higher Mg and Cr concentrations compared to the disseminated chromites in the serpentinites immediately adjacent to the chromite ore bodies and also slightly higher concentrations of Mg and Cr than the disseminated chromites in the host serpentinites. Fe2+, Mn, Zn, Al and V cations show exactly the opposite trend. We attribute these variations in the spinel chemistry to subsolidus reactions between chromite, silicate mineral phases and fluids. Geochemical maps presenting the spatial variation of these elements in disseminated Cr spinels of the Xerolivado mine can serve to delineate the precise position of the chrome ore bodies. © 2016 Elsevier B.V. Source

Allegrezza M.,Marche Polytechnic University | Ballelli S.,University of Camerino | Ciucci V.,Marche Polytechnic University | Mentoni M.,Geologist | Pesaresi S.,Marche Polytechnic University
Plant Sociology

We present here a detailed phytosociological study of the vegetation and the plant landscape of the north-eastern slopes of Monte Sassotetto (Sibillini Mountains, central Apennines), which is part of an extensive skiing area. The findings have revealed the high vegetational diversity of the study area, as shown by the 11 vegetational typologies identified, which are updated with the latest syntaxonomic and nomenclatural revisions. Nine of these belong to Habitats of Community Interest (SCI). The new associations described here are Gentiano luteae-Brachypodietum genuensis, Luzulo sieberi-Brachypodietum genuensis and Dichoropetalo carvifolii-chabraeii-Paeonietum italicae, as well as the subassociations and the syntaxon variants that have already been described in the literature. The geological and geomorphological variability, the vast areas of pasture land that have been long abandoned by traditional human activities, and the management of the ski slopes make this a territory that is indeed representative for the analysis of the biotic and abiotic ecological factors that can have effects on the phytocoenosis and species diversity. Along with the lithological characteristics, the geomorphology together with the steepness of the slopes and the acidity of the soil are the most significant abiotic factors for the interpretation of the vegetational diversity of this territory. For the grasslands, the study has allowed the indication in particular of Filipendulo vulgaris-Trifolietum montani (Habitat 6210*) as grassland communities at risk of disappearing due to the floristic-vegetational changes. Abandonment of the traditional human practices has triggered the natural dynamic processes of the vegetation. In locations where disturbance has been practically absent for a long time, under conditions of deep soil and prolonged snow cover, there has been progression of the natural dynamic processes. This has also been accelerated by the forest coenoses, which has led to the replacement of the grasslands included in the association Filipendulo vulgaris-Trifolietum montani (Habitat 6210*), with coenoses that are included in the class Trifolio-Geranietea, with the subsequent loss of this Habitat. Finally, the management of the snow cover in the preparation of the ski slopes is one of the ecological factors responsible for the acidification of the slope grasslands of the association Filipendulo vulgaris-Trifolietum montani, which is being replaced by the acidophilous microthermal grasslands of the association Gentiano luteae-Brachypodietum genuensis. © Italian Society for Vegetarian Science. Source

Beretta G.P.,University of Milan | Coppola G.,Geologist | Pona L.D.,A2A Calore and oServizi s.r.l. Development and Management of Heat District

The use of renewable resources has increased in Europe so that A2A Calore & Servizi, a leading company in the field of district heating in Milan (Italy) and the surrounding province, has built two co-generation power plants in order to produce heat from both conventional sources (combustion of natural gas in boilers, cogenerative engines and turbines) and through the exploitation of the geothermal potential of groundwater by a large heat pump (15. MWt). Geothermal exploitation is limited to the shallow aquifer; the temperature of which, below the first few metres, remains roughly constant throughout the year.Groundwater flow and heat transfer within the subsurface can be simulated using a numerical model to identify the pumping and recharge well layout that maximizes the efficiency of geothermal exploitation and groundwater protection.Starting with the similarity between solutes and heat transport within aquifers, different scenarios of heat pump operation in the Canavese power station, which has a maximum water withdrawal of 0.3m3/s, have been developed. © 2013 Elsevier Ltd. Source

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