3He/4He Ratio in Olivines from Linosa, Ustica, and Pantelleria Islands (Southern Italy)

We report helium isotope data for 0.03–1 Ma olivine-bearing basaltic hawaiites from three volcanoes of the southern Italy magmatic province (Ustica, Pantelleria, and Linosa Islands). Homogenous H3e/H4e ratios (range: 7.3–7.6 Ra) for the three islands, and their similarity with the ratio of modern volcanic gases on Pantelleria, indicate a common magmatic end-member. In particular, Ustica (7.6±0.2 Ra) clearly differs from the nearby Aeolian Islands Arc volcanism, despite its location on the Tyrrhenian side of the plate boundary. Although limited in size, our data set complements the large existing database for helium isotope in southern Italy and adds further constraints upon the spatial extent of intraplate alkaline volcanism in southern Mediterranea. As already discussed by others, the He-Pb isotopic signature of this magmatic province indicates a derivation from a mantle diapir of a OIB-type that is partially diluted by the depleted upper mantle (MORB mantle) at its periphery

Noble gases applied to the study of the pampeano aquifer

La solubilidad de los gases en agua es un proceso que puede ser acotado con un número reducido de variables ambientales. Los gases nobles, por su carácter no reactivo, son trazadores ideales para estudios en aguas subterráneas. Algunos de ellos son radionúclidos o productos de desintegración radiactiva, lo cual les confiere especial interés para la datación. En varias localizaciones en el sudeste de la provincia de Buenos Aires se tomaron muestras para la determinación de gases nobles por espectrometría de masas. Los resultados aportan al conocimiento en diferentes aspectos. Por una parte se ha determinado el componente de exceso de aire que se vincula con las oscilaciones del nivel freático. La temperatura del agua durante la recarga se calculó en un promedio de 13,4°C. La relación 3H/3He permite determinar un gradiente de edades desde 5 a más de 40 años, mientras que las concentraciones de 4He resultan adecuadas como indicador de edades relativas.Centro de Investigaciones Geológica

Noble gases applied to the study of the pampeano aquifer

La solubilidad de los gases en agua es un proceso que puede ser acotado con un número reducido de variables ambientales. Los gases nobles, por su carácter no reactivo, son trazadores ideales para estudios en aguas subterráneas. Algunos de ellos son radionúclidos o productos de desintegración radiactiva, lo cual les confiere especial interés para la datación. En varias localizaciones en el sudeste de la provincia de Buenos Aires se tomaron muestras para la determinación de gases nobles por espectrometría de masas. Los resultados aportan al conocimiento en diferentes aspectos. Por una parte se ha determinado el componente de exceso de aire que se vincula con las oscilaciones del nivel freático. La temperatura del agua durante la recarga se calculó en un promedio de 13,4°C. La relación 3H/3He permite determinar un gradiente de edades desde 5 a más de 40 años, mientras que las concentraciones de 4He resultan adecuadas como indicador de edades relativas.Centro de Investigaciones Geológica

Noble gases applied to the study of the pampeano aquifer

La solubilidad de los gases en agua es un proceso que puede ser acotado con un número reducido de variables ambientales. Los gases nobles, por su carácter no reactivo, son trazadores ideales para estudios en aguas subterráneas. Algunos de ellos son radionúclidos o productos de desintegración radiactiva, lo cual les confiere especial interés para la datación. En varias localizaciones en el sudeste de la provincia de Buenos Aires se tomaron muestras para la determinación de gases nobles por espectrometría de masas. Los resultados aportan al conocimiento en diferentes aspectos. Por una parte se ha determinado el componente de exceso de aire que se vincula con las oscilaciones del nivel freático. La temperatura del agua durante la recarga se calculó en un promedio de 13,4°C. La relación 3H/3He permite determinar un gradiente de edades desde 5 a más de 40 años, mientras que las concentraciones de 4He resultan adecuadas como indicador de edades relativas.Centro de Investigaciones Geológica

The spatial variability in isotopic composition of surface snow and snowpits on the East Antarctic Ice Sheet

The water isotope composition of snow precipitations, archived in the Antarctic ice sheet every year, is an important proxy of climatic conditions. This signal depends on several parameters such as local temperature, altitude, moisture source areas and air mass pathways. However, especially in areas where snow accumulation is very low (as on the East Antarctic Plateau), the isotopic composition is affected by additional spatial variability induced by the interactions between the atmosphere and snow surface, and the pristine signal may be modified through isotopic exchanges, sublimation processes and mechanical mixing originated from wind action. Here, we present the isotopic composition (D and 18O) and the second-order parameter d-excess of surface snow and snowpit samples collected during the Italian-French campaign in Antarctica (2019-2020). The sampling sites cover the area from Dumont D'Urville to Concordia Station and from Concordia Station towards the South Pole (EAIIST – East Antarctic International Ice Sheet Traverse). These data, compared with a previous dataset of Antarctic surface snow isotopic composition (Masson-Delmotte et al. 2008), are analyzed to determine the variability of the spatial relationship between precipitation isotopic composition and local temperature in relation to geographical parameters (latitude, distance from the coast and elevation). The interpretation of these factors determining the isotope signature is the base to better define the amount of the effects caused by subsequent interaction between atmosphere and surface snow, and by the wind action. Understanding the spatial variability of this proxy, which strongly decreases the signal-to-noise ratio, could permit to improve the use of the “isotopic thermometer” to quantify past changes in temperature based on the stable isotopic record of deep ice cores

Sub-millennial climate variability from high-resolution water isotopes in the EPICA Dome C ice core

The EPICA Dome C (EDC) ice core provides the longest continuous climatic record, covering the last 800 000 years (800 kyr). A unique opportunity to investigate decadal to millennial variability during past glacial and interglacial periods is provided by the high-resolution water isotopic record (δ18O and δD) available for the EDC ice core. We present here a continuous compilation of the EDC water isotopic record at a sample resolution of 11 cm, which consists of 27 000 δ18O measurements and 7920 δD measurements (covering, respectively, 94 % and 27 % of the whole EDC record), including published and new measurements (2900 for both δ18O and δD) for the last 800 kyr. Here, we demonstrate that repeated water isotope measurements of the same EDC samples from different depth intervals obtained using different analytical methods are comparable within analytical uncertainty. We thus combine all available EDC water isotope measurements to generate a high-resolution (11 cm) dataset for the past 800 kyr. A frequency decomposition of the most complete δ18O record and a simple assessment of the possible influence of diffusion on the measured profile shows that the variability at the multi-decadal to multi-centennial timescale is higher during glacial than during interglacial periods and higher during early interglacial isotopic maxima than during the Holocene. This analysis shows as well that during interglacial periods characterized by a temperature optimum at the beginning, the multi-centennial variability is strongest over this temperature optimum.publishedVersio

The extraordinary March 2022 East Antarctica "heat" wave. Part I: observations and meteorological drivers

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The extraordinary March 2022 East Antarctica "heat" wave. Part II: impacts on the Antarctic ice sheet

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Hydrothermal activity on Gakkel Ridge

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