1,721,176 research outputs found
Volatile and mobile element recycling during subduction of the oceanic lithosphere. Insights from metasediments and serpentinites of the Alps.
No full textWe discuss some aspects of the release of light elements and volatile components during subduction of serpentinite and metasedimentary systems. Enrichment in B, CI, and Sr during serpentinization of the oceanic mantle is followed by their progressive release in the subduction fluids. Olivine-orthopyroxene rocks formed after significant serpentinite dehydration still contain bulk B, CI and Li considerably higher than in mantle reservoirs and may introduce light element anomalies into the upper mantle. The high to ultrahigh pressure metasediments underwent little or no devolatilization, nor N release, down to at least 90 km, acting as closed systems to the infiltration of externally derived fluids. They therefore reflux to the mantle appreciable amounts of exogenic N. This behaviour is supported by the oxygen isotope geochemistry of high and ultrahigh pressure rocks, showing closed system behaviour and limited fluid mobility at these depths. Many high pressure rocks thus do not represent the levels of fluid extraction from slabs; we suggest that the antigorite breakdown may represent a dehydration reaction creating a mobile, trace element-enriched, subduction fluid
The composition and behaviour of fluids in high-pressure rocks from the Alps: a review
No full textIn Lombardo B. Ed.: “Studies on metamorphic rocks and minerals of the Western Alps. A volume in memory of Ugo Pognante” Bollettino del Museo Regionale di Scienze Naturali, Torin
Beauty is in the eyes of the perceiver: Impact of affective stereotyping on the perception of out-group members' facial expressions.
No full textHigh salinity brines in eclogiotized metabasites as the result of rock hydration during high-pressure metamorphism (Mt. Emilius Austroalpine unit, Italian Western Alps).
No full textSalt-rich aqueous fluids formed during eclogitization of metabasites in the Alpine continental crust (Austroalpine Mt. Emilius unit, Italian western Alps)
No full texthe metabasite bodies of the Mt. Emilius continental unit (western Italian Alps) underwent a stage of Alpine eclogite-facies metamorphism (1.1–1.3 GPa and 450–550°C) accompanied by polyphase deformation and recrystallization. The metabasites consist of two main rock types: (1) eclogites (omphacite+garnet+glaucophane+epidote+phengite/paragonite) preserving no relics of their precursors; (2) eclogitized granulites, i.e. rocks whose incomplete eclogitic recrystallization (clinopyroxene II+garnet II+epidote+amphibole+chlorite) allowed survival of textural and mineralogical relics of pre-Alpine granulitic assemblages (clinopyroxene I+garnet I+plagioclase+amphibole). In this latter case the pre-Alpine granulites were converted to eclogites as the result of infiltration of aqueous fluids during eclogitization. In both eclogites and eclogitized granulites hydrated high-pressure foliations are cut by eclogitic metamorphic veins. The bulk rock chemistry of the metabasites influenced the compositions of both the vein- and rock-forming clinopyroxenes and the compositional correlation between the vein- and rock-forming clinopyroxenes indicates that the syn-eclogitic fluids have re-equilibrated with the metabasite hosts. The predominant vein minerals (omphacite, epidote and garnet) contain primary high-salinity fluid inclusions. The fluids consist of two-phase (liquid+vapour) and of multiphase (liquid+vapour+salt+additional quartz) salty aqueous inclusions containing NaCl, CaCl2 and MgCl2 as the main chloride species. The vein inclusions show a salinity range from 17 to 45 wt.% salts in eclogites and from 20 to 50 wt.% salts in eclogitized granulites. In contrast, fluid inclusions in matrix minerals of the eclogitized granulites contain primary two-phase inclusions displaying a salinity range between 10 and 25 wt.% salts. The marked difference in fluid salinities recorded by the inclusions in the eclogitic veins and those in the partially re-equilibrated eclogitized granulites is interpreted in terms of progressive hydration during eclogitization of granulite-facies rocks, which caused an increase in the salt content of the residual inclusion fluids
Channelized aqueous fluids controlling eclogitization of granulitic protoliths from the Mt. Emilius Austroalpine unit (Western Alps)
No full textSalt-rich aqueous fluids formed during eclogitization of metabasites in the Alpine continental crust (Austroalpine Mt. Emilius unit, Italian Western Alps).
No full textFluid inclusion analysis as a calibration tool for exhumation rate studies: interpretation of fission-track data from the Western Alps.
No full textAmsterda
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