Publication Date:
2024-02-14
Description:
Some of the most CO2-rich magmas on Earth are erupted by intraplate ocean island volcanoes. Here, we characterise
olivine-hosted melt inclusions from recent (〈10 ky) basanitic tephra erupted by Fogo, the only active
volcano of the Cape Verde Archipelago in the eastern Atlantic Ocean. We determine H2O, S, Cl, F in glassy melt
inclusions and recalculate the total (glass + shrinkage bubbles) CO2 budget by three independent methodologies.
We find that the Fogo parental basanite, entrapped as melt inclusion in forsterite-rich (Fo80-85) olivines, contains
up to ~2.1 wt% CO2, 3–47 % of which is partitioned in the shrinkage bubbles. This CO2 content is among the
highest ever measured in melt inclusions in OIBs. In combination with ~2 wt% H2O content, our data constrain
an entrapment pressure range for the most CO2-rich melt inclusion of 648–1430 MPa, with a most conservative
estimate at 773–1020 MPa. Our results therefore suggest the parental Fogo melt is stored in the lithospheric
mantle at minimum depths of ~27 to ~36 km, and then injected into a vertically stacked magma ponding
system. Overall, our results corroborate previous indications for a CO2-rich nature of alkaline ocean island
volcanism. We propose that the Fogo basanitic melt forms by low degrees of melting (F = 0.06–0.07) of a carbonenriched
mantle source, containing up to 355–414 ppm C. If global OIB melts are dominantly as carbon-rich as
our Fogo results suggest, then OIB volcanism may cumulatively outgas
Description:
Published
Description:
93-111
Description:
OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
Description:
JCR Journal
Keywords:
Alkaline ocean islands
;
Intraplate volcanism
;
Fogo volcano
;
Melt inclusions
;
Cape Verde
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
