Publications des scientifiques de l'IRD

Lages J., Rizzo A. L., Aiuppa A., Samaniego Pablo, Le Pennec Jean-Luc, Ceballos J. A., Narvaez P. A., Moussallam Yves, Bani Philipson, Schipper C. I., Hidalgo S., Gaglio V., Alberti E., Sandoval-Velasquez A. (2021). Noble gas magmatic signature of the Andean Northern Volcanic Zone from fluid inclusions in minerals. Chemical Geology, 559, p. 119966 [16p.]. ISSN 0009-2541.

Titre du document
Noble gas magmatic signature of the Andean Northern Volcanic Zone from fluid inclusions in minerals
Année de publication
2021
Type de document
Article référencé dans le Web of Science WOS:000600546500033
Auteurs
Lages J., Rizzo A. L., Aiuppa A., Samaniego Pablo, Le Pennec Jean-Luc, Ceballos J. A., Narvaez P. A., Moussallam Yves, Bani Philipson, Schipper C. I., Hidalgo S., Gaglio V., Alberti E., Sandoval-Velasquez A.
Source
Chemical Geology, 2021, 559, p. 119966 [16p.] ISSN 0009-2541
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 He-3/He-4 ratios of 7.0-7.4 R-A, within the MORB range (8 +/- 1 R-A). 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 He-3/He-4 (8.5 +/- 0.3 R-A) for this volcanic system, which is in the range of fumarolic gases for Galeras (previously reported as high as 8.8 R-A and here measured to a maximum of 8.3 +/- 0.1 R-A). Our dataset highlights disparities between isotope signatures of eruptive products from Ecuador (avg. similar to 7.2 R-A) and those reported for the Colombian portion of the NVZ (avg. similar to 8.5 R-A). 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 R-A from the Ecuador average of 7.2) and Galeras and Nevado del Ruiz, whose maximum values differ by similar to 0.3 RA. We therefore suggest a homogenous MORB-like He-3/He-4 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/He-3 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.
Plan de classement
Géophysique interne [066]
Description Géographique
COLOMBIE ; EQUATEUR ; ANDES ; TUNGURAHUA VOLCAN ; EL REVENTADOR VOLCAN ; COTOPAXI VOLCAN ; GALERAS VOLCAN ; NEVADO DEL RUIZ VOLCAN
Localisation
Fonds IRD [F B010080531]
Identifiant IRD
fdi:010080531
Contact
  • Coordonnées :
    IST / IRD Ile-de-France
    32 avenue Henri Varagnat
    93140 Bondy Cedex
    France
    Horizon Pleins textes
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