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Dotsika, Elissavet
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- PublicationRestrictedA multidisciplinary geochemical approach to geothermal resource exploration: The Spezzano Albanese thermal system, southern Italy(2023-07-07)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ; This work aims to define the geothermal conceptual model of the Spezzano Albanese thermal system located in the northern sector of the Calabria Region, along the western edge of the Sibari Plain. The study confirms that the deep thermal reservoir of Spezzano Albanese is mainly hosted within the permeable levels of the evaporite deposits of the Messinian succession including siltstones with manganese mineralisation, halite, and gypsumarenites. The thermal waters show discharging temperature between 20.2 and 26.6 ◦C and a high compositional variability, from Na–Cl to Na–Ca–HCO3. The compositional evolution (from Na–Cl to Na–HCO3) is accompanied by a decrease in both salinity and the concentrations of most dissolved constituents, including Cl, Br, B, Li, Na, K, Mg, Ca, and Ba. These variations are due to mixing between the thermal endmember, rich in Cl and related components, and low-salinity, cold shallow waters (temperature between 17.5 and 22.7 ◦C). The study points out that the thermal endmember derives by halite dissolution and more complex water-rock interaction processes involving (1) the dissolution of other solid phases of the Messinian deposits, as also confirmed by δ34S values of dissolved sulphate and sulphide, and (2) the precipitation of secondary solid phases (e.g., barite). The geothermometric modelling suggests that the thermal groundwaters in the deep reservoir are probably in equilibrium with either (i) quartz, calcite, disordered dolomite, low-albite, and K-feldspar, as well as with pyrophyllite and poorly crystalline kaolinite (as proxies of clay minerals) at temperatures of 65.5 ± 4.5 ◦C or (ii) quartz, calcite, disordered dolomite, low-albite, disordered adularia, laumontite and saponites at temperatures of 56.1 ± 4.3 ◦C, based on the first and second geothermometric model, respectively. The δ18O and δ2H values of water confirm a meteoric origin for the thermal waters with average recharge altitudes between 745 and 857 m a.s.l. These elevations are compatible with the recharge from the western side of the Esaro valley where evaporite successions are found close to the surface. The isotopic value of the dissolved CO2 associated to the Spezzano Terme water highlights its likely microbial origin, as recognised for other thermal circuits hosted in sedimentary rocks of the southern Apennines. Furthermore, the thermal endmember shows a noteworthy enrichment in CH4 with respect to air due to the interaction of groundwater with sediments rich in organic matter. Although methane could have a biogenic origin, the presence of a minor component of thermogenic methane in the gas phase dissolved in the Spezzano Terme waters cannot be completely excluded. The data obtained in this study allow to assume that the recharge meteoric waters descend to a maximum depth of about 1.1–1.4 km below the main emergence area and then the regional NE-SW fault systems probably act as a preferential pathway for the ascent of the thermal waters towards the surface. These waters discharge at Spezzano Albanese, where the crystalline-metamorphic units cropping out immediately upstream of the emergence area act as cap-rock favouring the final ascent towards the surface of the thermal waters.156 18 - PublicationRestrictedEarly-middle Holocene land snail shell stable isotope record from Grotta di Latronico 3 (southern Italy)(2010-12)
; ; ; ; ; ; ; ;Colonese, A. C.; Departamento de Arqueologı´a y Antropologı´a (IMF – CSIC), Research group GASA (UAB), AGREST (Generalitat de Catalunya), Barcelona, Spain ;Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Dotsika, E.; Institute of Material Science, National Center for Scientific Research, Aghia Paraskevi, Attiki, Greece ;Drysdale, R. N.; Department of Resource Management and Geography, University of Melbourne, Victoria, Australia ;Fallick, A. E.; Scottish Universities Environmental Research Centre, East Kilbride, Glasgow, UK ;Grifoni Cremonesi, R.; Dipartimento di Scienze Archeologiche, University of Pisa, Pisa, Italy ;Manganelli, G.; Dipartimento di Scienze Ambientali, University of Siena, Siena, Italy; ; ; ; ; ; This paper compares stable isotope (δ18O and δ13C) records of early–middle Holocene land snail shells from the archaeological deposits of Grotta di Latronico 3 (LTR3; southern Italy) with modern shell isotopic data. No substantial interspecific variability was observed in shell δ18O (δ18Os) of modern specimens (Pomatias elegans, Cornu aspersum, Eobania vermiculata, Helix ligata and Marmorana fuscolabiata). In contrast, interspecific shell δ13C (δ13Cs) variability was significant, probably due to different feeding behaviour among species. The δ18Os values of living land snails suggest that species hibernate for a long period during colder months, so that the signal of 18O-depleted winter rainfall in their δ18Os is lost. This suggests that δ18Os and δ13Cs values of Pomatias elegans from this archaeological succession provide valuable clues for seasonal (spring–autumn) climatic conditions during the early–middle Holocene. The δ18Os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records, suggesting a substantial increase of precipitation and/or persistent changes in air mass source trajectories over this region between ca. 8.8 cal ka BP and 6.2–6.7 ka ago. The δ13Cs trend suggests a transition from a slightly 13C-enriched to a 13C-depleted diet between early and middle Holocene compared to present conditions. We postulate that this δ13Cs trend might reflect changes in the C3 vegetation community, potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric CO2 concentration. Copyright © 2010 John Wiley & Sons, Ltd.183 24 - PublicationOpen AccessEnvironmental variability between the penultimate deglaciation and the mid Eemian: Insights from Tana che Urla (central Italy) speleothem trace element record(2016)
; ; ; ; ; ; ; ; ; ; ;; ;; ; ; ; ; ;A trace element record (Mg, Sr, Ba, Al, Si, P, Y, Zn) covering the ca. 133 ka to ca. 124 ka time interval was acquired from a flowstone core from Tana che Urla Cave (central Italy). It was compared with stable isotope data to investigate the environmental evolution in response to regional and extra-regional climate changes in the period corresponding to the latter part of the Penultimate Deglaciation and the first part of the Last Interglacial (Eemian). Trace element geochemical changes on centennial and millennial time scales responded to changes in hydrological input, variations in the supply and transport of catchment erosion products to the cave, including those linked to intense rainfall events, and to the state of the overlying soil and vegetation. Abrupt increases in precipitation and the progressive development of soil and vegetation occurred at ca. 132 ka, in response to the development of the global deglacial phase. The major changes in trace element composition are coherent with the previous hydrological interpretation of speleothem oxygen stable isotope composition (δ18O) as predominantly a rainfall-amount proxy. However, reduced growth rate persisted until ca. 130 ka, suggesting still depressed temperatures. An abrupt event of climatic deterioration, with marked decrease in precipitation and soil degradation, is apparent between ca. 131 and 130 ka. Cool-wet conditions between ca. 132 and 131 ka and the subsequent dry period may represent the local hydrological response to an interval of North Atlantic cooling and ice-rafted-debris (IRD) deposition known as Heinrich event 11 (H11). After 129.6 ka there was a rapid recovery according to all of the studied speleothem properties, indicating the onset of full interglacial conditions. A minor amplitude event of reduced precipitation is recorded within the LIG at ca. 127 ka. The record highlights the growing regional evidence for a complex penultimate deglacial climate involving major reorganization of oceanic and atmospheric patterns.105 173