Publication Date:
2021-12-15
Description:
Gene rally, the intensity and magnitude of explosive volcanic activity increase in parallel with SiO2 content.
Pyro clasti cflow-forming eruptions in the Colli Albani ultrapotassic volcanic district (Italy) repres ent the most striking exception on a global scale, with volumes on the
order of tens of cubic kilometres and K-foiditic compositions (SiO2 even〈42 wt.%). Here, we reconstruct the pre-eruptive scenario and event dynamics of the ~456 ka
Pozzolane Rosse (PR) eruption, the largest mafic explosive event of the Colli Albani district. In particular, we focus on the driving mechanisms for the unusually explosive eruption of a low-viscosity, mafic magma. Geologic, petrographic and geochemical data with mass balance
calculations, supported by experimental data for Colli Albani magma compositions, provide evidence for significant ingestion of carbonate wall rocks by the Pozzolane
Rosse K-foiditic magma. Moreover, the scattered occurrence
of cored bombs in Pozzolane Rosse pyroclastic-flow deposits records carbonate entrainment even at the eruptive
time scale, as also tested quantitatively by thermal modelling of magma–carbonate interaction and carbonate assimilation
experiments. We suggest that the addition of free CO2 from decarbonation of country rocks was the major factor controlling magma explosivity. High CO2 activity in the
volatile component, coupled with magma depressurisation,
produced extensive leucite crystallisation at short time scal s, resulting in a dramatic increase in magma viscosity
and volatile pressurisation, which was manifested a change of eruptive dynamics from early effusion to the Pozzolane
Rosse's highly explosive eruption climax.
Description:
Published
Description:
241-256
Description:
2.3. TTC - Laboratori di chimica e fisica delle rocce
Description:
JCR Journal
Description:
restricted
Keywords:
Mafi c explosive erupt ions
;
Py roclasti c flow
;
Er uption magni tude
;
Colli Al bani
;
Po tassic volcan ism
;
Car bonate assi milation
;
05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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