Publication Date:
2017-04-04
Description:
Two unusual, highly explosive flank eruptions succeeded on Mount Etna in July
August 2001 and in October 2002 to January 2003, raising the possibility of changing
magmatic conditions. Here we decipher the origin and mechanisms of the second eruption
from the composition and volatile (H2O, CO2, S, Cl) content of olivine-hosted melt
inclusions in explosive products from its south flank vents. Our results demonstrate that
powerful lava fountains and ash columns at the eruption onset were sustained by
closed system ascent of a batch of primitive, volatile-rich ( 4 wt %) basaltic magma that
rose from 10 km depth below sea level (bsl) and suddenly extruded through 2001
fractures maintained opened by eastward flank spreading. This magma, the most primitive
for 240 years, probably represents the alkali-rich parental end-member responsible for
Etna lavas’ evolution since the early 1970s. Few of it was directly extruded at the eruption
onset, but its input likely pressurized the shallow plumbing system several weeks before
the eruption. This latter was subsequently fed by the extrusion and degassing of larger
amounts of the same, but slightly more evolved, magma that were ponding at 6–4 km bsl,
in agreement with seismic data and with the lack of preeruptive SO2 accumulation above
the initial depth of sulphur exsolution ( 3 km bsl). We find that while ponding, this
magma was flushed and dehydrated by a CO2-rich gas phase of deeper derivation, a
process that may commonly affect the plumbing system of Etna and other alkali basaltic
volcanoes.
Description:
Published
Description:
B04203
Description:
reserved
Keywords:
NONE
;
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
1729601 bytes
Format:
application/pdf
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