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Guidi, Massimo
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- PublicationRestrictedAnomalous gas emission offshore from Panarea Island (Aeolian Arc, Italy)(2003-07-14)
; ; ; ; ; ; ; ; ;Carapezza, M.L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Caramanna, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Quattrocchi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Piccione, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Barberi, F. ;Cioni, R. ;Guidi, M. ;Lelli, M.; ; ; ; ; ; ;Panarea Island is located in the eastern sector of the Aeolian arc at only 20 km from the active volcano of Stromboli. Its recentmost volcanic products date back to about 50 ka but a probable submarine eruption occurred there in 126 B.C. Near to volcanic islets 3 km E of Panarea, on 3 November 2002 an impressive submarine gas emission began from several points at a depth 8-20 m. The strongest gas emission, with jet velocity of 1 m/s, occurred from a small depression, possibly produced by a weak submarine phreatic explosion. Most of the gas was emitted from NE-SW trending fissures, whose direction matches with the main tectonic lineament of the Panarea- Stromboli sector. Only a very weak local seismicity was recorded. Gas was sampled and the physico-chemical characteristics of the seawater (T, pH, Eh, dissolved O2,) were measured in two campaigns carried out in November and in December. Gas mostly consists of CO2 (95-98.2 vol % ) and H2S (0.7-2%). Compared with previous chemical data on the submarine fumaroles of the same area, the 2002 emission is characterized by a marked increase of H2 and a decrease of the CH4/CO ratio. These data indicate the presence of high-temperature components with a likely magmatic provenance raised from a pressurized system through newly opened fractures. The sea water was chemically modified over a wide area, as indicated by the low pH and Eh values. In the first months of 2003 the gas emission started to decline, but it was still clearly visible four months after its beginning. This phenomenon recalled the attention on the volcanic hazard related to a possible submarine eruption near Panarea, where over 10,000 people live in the tourist season.181 27 - PublicationRestrictedHypogean microclimatology and hydrology of the 800-900m a.s.l. level in the Monte Corchia Cave (Tuscany Italy) - preliminary consideration and implications for paleoclimatological studies(2011)
; ; ; ; ; ; ; ; ; ; ;Baneschi, I.; Istituto di Geoscienze e Georisorse – CNR, Pisa, Italia ;Piccini, L.; Dipartimento di Scienze della Terra, Università di Firenze, Firenze, Italia ;Regattieri, E.; Dipartimento di Scienze della Terra, Università di Firenze, Firenze, Italia ;Isola, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Guidi, M.; Istituto di Geoscienze e Georisorse – CNR, Pisa, Italia ;Lotti, L.; Agenzia Regionale per la protezione Ambientale della Toscana (ARPAT) – Dipartimento Provinciale di Massa, Massa, Italia. ;Mantelli, F.; Agenzia Regionale per la protezione Ambientale della Toscana (ARPAT) – Dipartimento Provinciale di Firenze, Firenze, Italia. ;Menichetti, M.; Dipartimento di Geologia e Tecnologie Chimiche Ambientali Università di Urbino, Urbino, Italy ;Drysdale, R. N.; School of Environmental and Life Sciences, University of Newcastle, Callaghan, Australia ;Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; ; ; ; ; ; ; ; ; Ilaria Baneschi, Leonardo Piccini, Eleonora Regattieri, Ilaria Isola, Massimo Guidi, Licia Lotti, Francesco Mantelli, Marco Menichetti, Russell N. Drysdale & Giovanni Zanchetta: Hypogean microclimatology and hydrogology of the 800-900 m asl level in the Monte Corchia cave (Tuscany, Italy): Preliminary considerations and implications for paleoclimatological studies The Monte Corchia Cave is one of the most promising sites for studying the paleoclimate of the Mediterranean basin, but its hydrology and hydrogeochemistry are still poorly known. In this paper, we report some meteoclimatic and hydrochemical data for different parts of the cave. Conductivity and water level data from La Gronda channel show that this system reacts rapidly to external meteoric events, indicating the presence of a conductive epikarst. Data on two different drips indicate that the physicochemical parameters, such as conductivity, pH, δ13CDIC and drip rate depend on the local structural setting and water path length. The data presented show that Galleria delle Stalattiti (the focus of the paleoclimate research) has the most stable conditions in terms of temperature, and the dripwaters show constant pH, electrical conductivity, alkalinity, calcium and magnesium content and δ18O. Drip rate is not affected by rain events and displays long-term trends that require a longer period of monitoring for elucidating their nature. The preliminary data presented here corroborate the hypotheses suggesting Galleria delle Stalattiti as a good example of a “deep” hypogean system of Fairchild et al. (2007).394 28 - PublicationOpen AccessStable Oxygen and Carbon Isotope Composition of Holocene Mytilidae from the Camarones Coast (Chubut, Argentina): Palaeoceanographic Implications(2020)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The stable isotope composition of living and of Holocene Mytilidae shells was measured in the area of Camarones (Chubut, Argentina). The most striking results were the high 18O values measured in samples older than ca. 6.1 cal ka BP. In the younger samples, the 18O values remained substantially stable and similar to those of living specimens. Analysis of the data revealed the possibility for this isotopic shift to be driven mainly by changes in temperature probably accompanied by minor changes in salinity, suggesting cooler seawater before 6.1 cal ka BP, with a maximum possible temperature shift of ca. 5 C. A possible explanation of this change can be related to a northward position of the confluence zone of the Falkland and Brazilian currents. This is consistent with the data obtained in marine cores, which indicate a northerly position of the confluence in the first half of the Holocene. Our data are also in line with the changes in wind strength and position of the Southern WesterliesWind, as reconstructed in terrestrial proxies from the Southernmost Patagonia region.160 26 - PublicationOpen AccessPartitioning of Mg, Sr, Ba and U into a subaqueous calcite speleothem(2019)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The trace-element geochemistry of speleothems is becoming increasingly used for reconstructing palaeoclimate, with a particular emphasis on elements whose concentrations vary according to hydrological conditions at the cave site (e.g. Mg, Sr, Ba and U). An important step in interpreting trace-element abundances is understanding the underlying processes of their incorporation. This includes quantifying the fractionation between the solution and speleothem carbonate via partition coefficients (where the partitioning (D) of element X (DX) is the molar ratio [X/Ca] in the calcite divided by the molar ratio [X/Ca] in the parent water) and evaluating the degree of spatial variability across time-constant speleothem layers. Previous studies of how these elements are incorporated into speleothems have focused primarily on stalagmites and their source waters in natural cave settings, or have used synthetic solutions under cave-analogue laboratory conditions to produce similar dripstones. However, dripstones are not the only speleothem types capable of yielding useful palaeoclimate information. In this study, we investigate the incorporation of Mg, Sr, Ba and U into a subaqueous calcite speleothem (CD3) growing in a natural cave pool in Italy. Pool-water measurements extending back 15 years reveal a remarkably stable geochemical environment owing to the deep cave setting, enabling the calculation of precise solution [X/Ca]. We determine the trace element variability of ‘modern’ subaqueous calcite from a drill core taken through CD3 to derive DMg, DSr, DBa and DU then compare these with published cave, cave-analogue and seawater-analogue studies. The DMg for CD3 is anomalously high (0.042 ± 0.002) compared to previous estimates at similar temperatures ( 8 C). The DSr (0.100 ± 0.007) is similar to previously reported values, but data from this study as well as those from Tremaine and Froelich (2013) and Day and Henderson (2013) suggest that [Na/Sr] might play an important role in Sr incorporation through the potential for Na to outcompete Sr for calcite non-lattice sites. DBa in CD3 (0.086 ± 0.008) is similar to values derived by Day and Henderson (2013) under cave-analogue conditions, whilst DU (0.013 ± 0.002) is almost an order of magnitude lower, possibly due to the unusually slow speleothem growth rates (<1 lm a 1), which could expose the crystal surfaces to leaching of uranyl carbonate. Finally, laser-ablation ICP-MS analysis of the upper 7 lm of CD3, regarded as ‘modern’ for the purposes of this study, reveals considerable heterogeneity, particularly for Sr, Ba and U, which is potentially indicative of compositional zoning. This reinforces the need to conduct 2D mapping and/or multiple laser passes to capture the range of time-equivalent elemental variations prior to palaeoclimate interpretation.183 70