Search results for "Volcanology"

Simulation des sorties d'eau et de nitrates de parcelles agricoles drainées. Cas du site expérimental de Virey-le-Grand (71)

2003

Signatures terrigène et volcanique des bassins sédimentaires : implications stratigraphiques et paléoclimatiques

2018

Phase equilibrium constraints on the production and storage of peralkaline silicic magmas: insights from Kenya and Pantelleria.

2005

The origin of peralkaline silicic rocks is still obscure and stands perhaps as one of the last major unsettled issues in classic igneous petrology. The debate goes back to the end of the 18th century and despite intensive petrological, geochemical and laboratory efforts the consensus has yet to emerge as to which mechanisms produce peralkaline derivatives. Bowen (1937) first proposed that the shift from metaluminous to peralkaline field was due to extensive fractionation of calcic plagioclase. Perhaps the best illustration of such an hypothesis is provided by the Boina rock series in the Ethiopian rift studied by Barberi et al. (1975). However, such an hypothesis still awaits experimental c…

In-situ characterisation of aerosol and gases (SO 2 , HCl, ozone) in Mt Etna volcano plume

2015

International audience; We present findings from a measurement campaign that deployed a range of in-situ real-time atmospheric measurement techniques to characterise aerosols and gases in Mt Etna plume in October 2013. The LOAC (Light Optical Aerosol Counter) instrument for size-resolved particle measurements was deployed alongside two Multi-Gas instruments (measuring SO 2 , H2S, HCl, CO 2) and an ozone sensor. Measurements were performed at the summit craters (in cloudy-and non-cloudy conditions) and in grounding downwind plume on the volcano flank. These high frequency measurements (acid gases: 1 to 0.1 Hz, aerosol: 0.1 Hz) provide a detailed in-situ dataset for time-resolved plume charac…

Experimental Crystallization of a High-K Arc Basalt: the Golden Pumice, Stromboli Volcano (Italy)

2006

International audience; The near-liquidus crystallization of a high-K basalt (PST-9 golden pumice, 49·4 wt % SiO2, 1·85 wt % K2O, 7·96 wt % MgO) from the present-day activity of Stromboli (Aeolian Islands, Italy) has been experimentally investigated between 1050 and 1175°C, at pressures from 50 to 400 MPa, for melt H2O concentrations between 1·2 and 5·5 wt % and {Delta}NNO ranging from –0·07 to +2·32. A drop-quench device was systematically used. AuPd alloys were used as containers in most cases, resulting in an average Fe loss of 13% for the 34 charges studied. Major crystallizing phases include clinopyroxene, olivine and plagioclase. Fe–Ti oxide was encountered in a few charges. Clinopyro…

Magma and volatile supply to post-collapse volcanism and block resurgence in Siwi caldera (Tanna Island, Vanuatu arc)

2011

Siwi caldera, in the Vanuatu arc (Tanna island), is a rare volcanic complex where both persistent eruptive activity (Yasur volcano) and rapid block resurgence (Yenkahe horst) can be investigated simultaneously during a post-caldera stage. Here we provide new constraints on the feeding system of this volcanic complex, based on a detailed study of the petrology, geochemistry and volatile content of Yasur-Siwi bulk-rocks and melt inclusions, combined with measurements of the chemical composition and mass fluxes of Yasur volcanic gases. Major and trace element analyses of Yasur-Siwi volcanic rocks, together with literature data for other volcanic centers, point to a single magmatic series and p…

Unrest at the Nevados de Chillán volcanic complex: a failed or yet to unfold magmatic eruption?

2018

Resuming erupting activity at volcanoes that have been long quiescent poses a significant challenge to hazard assessment, as it require assessment of whether the change in activity is an isolated event or the beginning of a new eruptive sequence. Such inception is often poorly characterised as quiescent volcanoes tend to be poorly equipped and not extensively monitored, especially with respect to gas geochemistry. Here, we report gas composition and flux measurements from a newly opened vent at the very onset of eruptive activity at the Nevados de Chillán volcanic complex (Chile) in January-February 2016. The molar proportions of H2O, CO2, SO2, H2S and H2 gases are found to be 98.4, 0.97, 0…

Recent advances in ground-based ultraviolet remote sensing of volcanic SO2 fluxes

2011

Measurements of volcanic SO2 emission rates have been the mainstay of remote-sensing volcanic gas geochemistry for almost four decades, and they have contributed significantly to our understanding of volcanic systems and their impact upon the atmosphere. The last ten years have brought step-change improvements in the instrumentation applied to these observations, which began with the application of miniature ultraviolet spectrometers that were deployed in scanning and traverse configurations, with differential optical absorption spectroscopy evaluation routines. This study catalogs the more recent empirical developments, including: ultraviolet cameras; wide-angle field-of-view differential …

Os, Sr, Nd, Pb, O isotope and trace element data from the Ferrar flood basalts, antarctica: evidence for an enriched subcontinental lithospheric sour…

1996

Os, Sr, Nd, Pb and O isotopes and trace element data are reported for basaltic andesite and andesite whole rocks and, in part, for selected mineral separates from the Jurassic Ferrar flood basalt province. Radiogenic Sr (> 0.709), unradiogenic Nd (εNd= −3 to −5), and radiogenic Pb isotopes, as well as low Nb/La ratios of 0.4 – 0.6 and Nb/La ratios between 0.45 and 0.6 are found for all rocks including our most primitive sample (Mg# = 71.9). This indicates involvement of either continental crust or enriched lithospheric mantle in magma genesis. 187Re/188Os correlates strongly with 187Os/188Os, with an age of 172 ± 5 Ma, in agreement with published Arsingle bondAr data. Initial 187Os/188Os of…

2020

Although volcanic eruptions represent short periods in the whole history of a volcano, the large amount of loose pyroclastic material produced, combined with aeolian processes, can lead to continuous, long-lasting reworking of volcanic products. Driven by wind, these processes significantly influence the geomorphology and prolong the impacts of eruptions on exposed communities and ecosystems. Since such phenomena are of interest to scientists from a range of disciplines (e.g. volcanology, atmospheric and soil sciences), a well-defined, common nomenclature is necessary to optimize the multidisciplinary characterisation of both processes and deposits. We, therefore, first describe ash wind-re…