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  • Noble gases  (3)
  • Elsevier  (3)
  • American Association for the Advancement of Science
  • Annual Reviews
  • Blackwell Publishing Ltd
  • International Union of Crystallography
  • Oxford University Press
  • Springer Nature
  • 2020-2024  (3)
  • 2005-2009
  • 1980-1984
  • 1930-1934
  • 1925-1929
  • 2020  (3)
  • 1984
  • 1927
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  • Elsevier  (3)
  • American Association for the Advancement of Science
  • Annual Reviews
  • Blackwell Publishing Ltd
  • International Union of Crystallography
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  • 2020-2024  (3)
  • 2005-2009
  • 1980-1984
  • 1930-1934
  • 1925-1929
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  • 1
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    Subduction-related melt refertilisation and alkaline metasomatism in the Eastern Transylvanian Basin lithospheric mantle: Evidence from mineral chemistry and noble gases in fluid inclusions (2020)
    Elsevier
    Details
    Publication Date: 2023-10-25
    Description: Calc-alkaline and alkaline magmatic activity is generally separated in space and/or in time. The Eastern Transylvanian Basin in Romania is one of the few places where, during Pleistocene, alkaline eruptions occurred contemporaneously with the calc-alkaline activity. Mantle xenoliths entrained in Perşani Mts. alkaline volcanic products have been studied in order to investigate the interaction of metasomatic agents of different magmatic affinities with the mantle wedge. Based on mineral major and trace element and noble gases in fluid inclusions, two main events have been recognized. The first was a pervasive, complete re-fertilization of a previously depleted mantle by a calc-alkaline subduction-related melt, causing the formation of very fertile, amphibole-bearing lithotypes. This is shown by the a) increased amounts of modal clinopyroxene up to 21.9 % with Al2O3 contents up to 8.16 wt%, higher than what is expected for clinopyroxene in Primordial Mantle; b) 4He/40Ar* ratios up to 1.2, within the reported range for mantle production; c) 3He/4He in olivine, opx and cpx of 5.8 ± 0.2 Ra, among the most radiogenic values of European mantle, below the typical MORB mantle value (8 ± 1 Ra), reflecting recycling of crustal material in the local lithosphere. The second event is related to later interaction with an alkaline metasomatic agent similar to the host basalts that caused slight LREE enrichment in pyroxenes and disseminated amphiboles and precipitation of vein amphiboles with a composition similar to amphiboles megacrysts also found in the Perşani Mts. volcanic deposits. This is highlighted by the 4He/40Ar* and 3He/4He values found in some opx and cpx, up to 2.5 and 6.6 Ra, respectively, more typical of magmatic fluids.
    Description: Published
    Description: 105516
    Description: 1T. Struttura della Terra
    Description: 1V. Storia eruttiva
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Keywords: Mantle refertilisation ; Eastern Transylvanian Basin ; Noble gases ; Post-collisional ; Subduction-related metasomatism ; Solid Earth ; 04.01. Earth Interior
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    The role of trapped fluids during the development and deformation of a carbonate/shale intra-wedge tectonic mélange (Mt. Massico, Southern Apennines, Italy) (2020)
    Elsevier
    Details
    Publication Date: 2023-10-26
    Description: Numerous studies exist on exhumed tectonic mélanges along subduction channels whereas, in accretionary wedge interiors, deformation mechanisms and related fluid circulation in tectonic mélanges are still underexplored. We combine structural and microstructural observations with geochemical (stable and clumped isotopes and isotope composition of noble gases in fluid inclusions of calcite veins) and U-Pb geochronological data to define deformation mechanisms and syn-tectonic fluid circulation within the Mt. Massico intra-wedge tectonic mélange, located in the inner part of the central-southern Apennines accretionary wedge, Italy. This mélange developed by shear deformation at the base of a clastic succession. Deformation was characterized by disruption of the primary bedding, mixing, and deformation of relicts of competent olistoliths and strata within a weak matrix of deformed clayey and marly interbeds. Recurrent cycles of mutually overprinting fracturing/veining and pressure-solution processes generated a block-in-matrix texture. The geochemical signatures of syntectonic calcite veins suggest calcite precipitation in a closed system from warm (108°-147 °C) paleofluids, with δ18O vlaues between þ9‰ and 14‰, such as trapped pore waters after extensive 18O exchange with the local limestone host rock and/or derived by clay dehydration processes at T 〉 120 °C. The 3He/4He ratios in fluid inclusions are lower than 0.1 Ra, indicating that He was exclusively sourced from the crust. We conclude that: (1) intraformational rheological contrasts, inherited trapped fluids, and low-permeability barriers such as marlyshaly matrix, can promote the generation of intra-wedge tectonic mélanges and the development of transient fluid overpressure; (2) clay-rich tectonic mélanges, developed along intra-wedge décollement layers, may generate low-permeability barriers hindering the fluid redistribution within accretionary wedges.
    Description: Published
    Description: 104086
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Tectonic mélange ; Fluid-rock interaction ; Stable and clumped isotopes ; Noble gases ; Fold and thrust belt ; 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Noble gas magmatic signature of the Andean Northern Volcanic Zone from fluid inclusions in minerals (2020)
    Elsevier
    Details
    Publication Date: 2023-11-21
    Description: Trace volatile elements like He are key for understanding the mantle source signature of magmas and to better constrain the relative roles of subduction and crustal processes to the variability of along-arc chemical and isotopic signatures of magmatic fluids. Here we report on noble gas abundances and isotopic data of Fluid Inclusions (FIs) in eruptive products and/or fumarolic gases from the Colombia-Ecuador segment of Andean Northern Volcanic Zone (NVZ). FIs in olivine phenocrysts from Ecuador (El Reventador, Cotopaxi and Tungurahua) yield air-normalized corrected 3He/4He ratios of 7.0–7.4 RA, within the MORB range (8 ± 1 RA). With exception of the Cotopaxi lavas (opx 〈 〈oliv.), these are indistinguishable of those obtained for their cogenetic orthopyroxene pairs and of gas emissions previously reported in literature. Olivine phenocrysts from Nevado del Ruiz fissure lavas also yield the highest 3He/4He (8.5 ± 0.3 RA) for this volcanic system, which is in the range of fumarolic gases for Galeras (previously reported as high as 8.8 RA and here measured to a maximum of 8.3 ± 0.1 RA). Our dataset highlights disparities between isotope signatures of eruptive products from Ecuador (avg. ~7.2 RA) and those reported for the Colombian portion of the NVZ (avg. ~8.5 RA). Previous studies on the geochemistry of erupted products put in evidence significant along-arc variations ascribed either to the involvement of different slab components, or to variable depths of evolution of arc magmas within the continental crust. However, the same variation is not discernible in the signature of noble gases, especially helium, from FIs and gas emissions analyzed in this study, with little inter-variation between Cotopaxi, Reventador and Tungurahua (all within 0.2 RA from the Ecuador average of 7.2) and Galeras and Nevado del Ruiz, whose maximum values differ by ~0.3 RA. We therefore suggest a homogenous MORB-like 3He/4He signature for the mantle wedge beneath this arc segment, whereby along-arc variations in crustal thickness (from 〈35 km at the northernmost part of the segment to ≥50 km at the Ecuadorian arc segment) may factor largely into the variability recorded on our data set. The first CO2/3He ratios obtained in FIs from Andean rocks support the hypothesis of increasing crustal contamination from Colombia to Ecuador, concomitant with increasing crustal thicknesses under the respective arc regions.
    Description: Published
    Description: 119966
    Description: 1V. Storia eruttiva
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: Andean Volcanic Belt ; Northern Volcanic Zone ; Fluid inclusions ; Noble gases ; Helium ; Crustal thickness ; 04.08. Volcanology ; 04.01. Earth Interior
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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