Publication Date:
2021-12-15
Description:
Eruptive scenarios associated with the possible reactivation of maar-forming events in the Quaternary,
ultrapotassic Colli Albani Volcanic District (CAVD) provides implications for volcanic hazard assessment in
the densely populated area near Rome. Based on detailed stratigraphy, grain size, componentry, ash
morphoscopy and petro-chemical analyses of maar eruption products, along with textural analysis of cored
juvenile clasts, we attempt to reconstruct the eruptive dynamics of the Prata Porci and Albano maars, as
related to pre- and syn-eruptive interactions between trachybasaltic to K-foiditic feeder magmas and
carbonate–silicoclastic and subvolcanic country rocks. Magma volumes in the order of 0.5–3.1×108 m3 were
erupted during the monogenetic Prata Porci maar activity and the three eruptive cycles of the Albano
multiple maar, originating loose to strongly lithified, wet and dry pyroclastic surge deposits, Strombolian
scoria fall horizons and lithic-rich explosion breccias. These deposits contain a wide range of accessory and
accidental lithic clasts, with significant vertical stratigraphic variations in the lithic types and abundances.
The two maar study cases hold a record of repeated transitions between magmatic (i.e, Strombolian fallout)
and hydromagmatic (wet and dry pyroclastic surges) activity styles. Evidence of phreatic explosions, a
common precursor of explosive volcanic activity, is only found at the base of the Prata Porci eruptive
succession. The quantitative evaluation of the proportions of the different eruptive styles in the stratigraphic
record of the two maars, based on magma vs. lithic volume estimates, reveals a prevailing magmatic
character in terms of erupted magma volumes despite the hydromagmatic footprint. Different degrees of
explosive magma–water interaction were apparently controlled by the different hydrogeological and
geological–structural settings. In the Prata Porci case, shifts in the depth of magma fragmentation are
proposed to have accompanied eruption style changes. In the Albano case, a deeply dissected geothermal
aquifer in peri-caldera setting and variable mass eruption rates were the main controlling factors of repeated
shifts in the eruptive style. Finally, textural evidence from cored juvenile clasts and analytical modeling of
melt–solid heat transfer indicate that the interacting substrate in the Prata Porci case was at low, uniform
temperature (~ 100 °C) as compared to the highly variable temperatures (up to 700–800 °C) inferred for the
geothermal system beneath Albano.
Description:
Protezione Civile,
Italy 2004–2006 Agreement with Istituto
Nazionale di Geofisica e Vulcanologia— INGV, project V3_1
Description:
Published
Description:
189-202
Description:
3.6. Fisica del vulcanismo
Description:
JCR Journal
Description:
reserved
Keywords:
maar
;
hydromagmatic eruption
;
04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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