Search results for "LCA"

Chlorophyll a fluorescence in transplants of Parmelia sulcata Taylor near a power station (La Robla, León, Spain)

2006

Healthy thalli of Parmelia sulcata Taylor were transplanted to 8 localities in the surroundings of a power station (La Robla, León, Spain), the sole pollution source in the region. Changes in chlorophyll a fluorescence were monitored in the transplants 12 months, 18 months and 24 months after transplantation. Statistically significant differences were observed in the ratio of variable to maximal fluorescence, non-photochemical fluorescence quenching and vitality index. The decrease in fluorescence parameters was higher in the localities of Cuadros and Rabanal de Fenar, which are situated a few kilometres away from the power station and in the same direction as the prevailing winds.

Nuovi ritrovamenti di resti di vertebrati nel travertino di Alcamo (TP).

2015

I depositi di travertino di Alcamo (TP) sono noti sin dal 1928 soprattutto per aver restituito resti dell’elefante di piccola taglia Paleoloxodon falconeri. Intorno agli anni ’80 nella cava di Contrada Cappuccini i lavori di coltivazione portarono alla luce una grossa frattura nel travertino. La frattura, riempita di un paleosuolo e chiaramente successiva alla formazione del travertino, conteneva un’associazione fossile caratterizzata dalla presenza di Paleoloxodon mnaidriensis. Il fatto che il paleosuolo contenga tali resti, assenti nel bancone di travertino caratterizzato invece dalla presenza dell’elefante di piccola taglia, costituisce un'inoppugnabile prova stratigrafica sulla successi…

Tree rings and volcanic cooling

2012

DEEP RESERVOIR TEMPERATURES OF LOW-ENTHALPY GEOTHERMAL SYSTEMS IN TUNISIA: NEW CONSTRAINTS FROM CHEMISTRY OF THERMAL WATERS

2012

Tunisia is characterized by hot and warm groundwaters (temperature up to 75 °C) which represent the surface manifestation of geothermal systems hosted in carbonate-evaporite rock sequences. The T-conditions of Tunisia deep thermal reservoirs are here evaluated for the first time at the regional scale. The results here shown clearly highlight the limitations inherent in the application of common geothermometric methods in the estimation of equilibrium temperatures in sedimentary environments. The modeling approach proposed by Chiodini et alii (1995), which makes use of the ratios between dissolved HCO3, SO4 and F, provides the most reliable results, and allows us to derive equilibrium temper…

Regional variations in the chemical and helium–carbon isotope composition of geothermal fluids across Tunisia

2011

Abstract Tunisia has numerous thermo-mineral springs. Previous studies have shown that their chemical composition and occurrence are strongly influenced by the regional geology. However little work has been done so far to study the isotopic composition of volatiles associated with these geothermal manifestations. Here, we report on the results of an extensive survey of both natural hot springs and production wells across Tunisia, aimed at investigating the spatial distribution of thermal fluids' geochemical characteristics and He–C isotopic composition. The chemistry of the analyzed samples highlights the heterogeneity of the water mineralization processes in Tunisia, as a consequence of th…

Anthropogenic travertine between History, Archaeology and Environment: a geoarchaeological study of the Roman site of Jebel Oust, Tunisia.

2013

Travertine, known as lapis tiburtinus during Roman times, are continental limestones precipitated in calcareous environments from thermal waters of hot springs (travertine) or cool waters of karstic springs (calcareous tufa). This phenomenon is well-known during Classical Antiquity and had been described by several ancient authors (Strabo, Pliny the Elder, Vitruvius) who depicted a stone that forms extremely rapidly, a stone that outlines the landscape and which is largely used for construction (e.g. The Colosseum in Roma, the Greek temple at Segesta in Sicily). These deposits are widespread on Earth’s surface showing various morphologies and are great sedimentary records of climatic and hy…

Submarine deposits from pumiceous pyroclastic density currents traveling over water: An outstanding example from offshore Montserrat (IODP 340)

2017

© 2016. Geological Society of America. All right reserved. Pyroclastic density currents have been observed to both enter the sea, and to travel over water for tens of kilometers. Here, we identified a 1.2-m-thick, stratified pumice lapilli-ash cored at Site U1396 offshore Montserrat (Integrated Ocean Drilling Program [IODP] Expedition 340) as being the first deposit to provide evidence that it was formed by submarine deposition from pumice-rich pyroclastic density currents that traveled above the water surface. The age of the submarine deposit is ca. 4 Ma, and its magma source is similar to those for much younger Soufrière Hills deposits, indicating that the island experienced large-magnitu…

Environmental and depositional controls on laminated freshwater carbonates: An example from the Roman aqueduct of Patara, Turkey

2013

Carbonate deposits in aqueducts are a new high-resolution data source for environmental changes during the time of the Roman Empire, notably in the fields of palaeoclimate and spring hydrology. In order to distinguish environmental effects from those related to depositional setting, laminated carbonate deposits were compared along the entire length of an ancient aqueduct channel at Patara, Turkey. The carbonate deposits, up to 80mm in thickness, are composed of lamina couplets up to 1mm thick of alternating porous microspar and dense, columnar sparite. The former formed in the dry, warm season and the latter in the wet, cool season. The presence of biofilms seems to play a role in the devel…

El periodismo sefardí ante su público

2012

El presente trabajo tiene como objeto de estudio la prensa periódica sefardí, que apareció a mediados del s. XIX en los territorios del antiguo Imperio Otomano y se extendió hasta la llegada de la II Guerra Mundial.La prensa periódica, que a mediados del s. XIX ya contaba con una consolidada tradición en Occidente, fue un género literario que los sefardíes otomanos adoptaron de la vecina Europa. Si bien su práctica no fue muy intensa en los primeros años, desde las últimas décadas del s. XIX y, especialmente, a partir de 1908 (fecha de la Revolución de los Jóvenes Turcos), el periodismo sefardí alcanzó una elevada productividad. El motivo fue el fin de la censura del sultán Abdul Hamid II, …

Benthic foraminifera as indicators of relative sea-level fluctuations: Paleoenvironmental and paleoclimatic reconstruction of a Holocene marine succe…

2017

This study presents the results of an integrated stratigraphic analysis conducted on a marine gravity core (MSK-12 C4) recovered from the outer continental shelf (82 mwater depth) of western Calabria, ~2.6 km, NE of Capo Vaticano (Eastern Tyrrhenian margin). The gravity core MSK-12 C4 recovered a stratigraphic succession of 4.18 m beneath the seafloor representing the last ~11.1 ka. Sedimentological analysis, micropaleontological quantitative analysis on benthic foraminiferal assemblages, tephrostratigraphy, sequence stratigraphic analysis of high resolution reflection seismic data recorded in the core site area and AMS 14C absolute age determinations allowed reconstructing the marine recor…