Publication Date:
2017-04-04
Description:
New Sr and Nd isotope data for whole rocks,
glasses and minerals are combined to reconstruct the nature
and origin of mixing end-members of the 200 km3 trachytic
to phonolitic Campanian Ignimbrite (Campi Flegrei, Italy)
magmatic system. The least-evolved magmatic end-member
shows equilibrium between host glass and the majority of
the phenocrysts and is less radiogenic in Sr and Nd than
the most-evolved magma. On the contrary, only the Fe-rich
pyroxene from the most-evolved erupted magma is in
equilibrium with the matrix glass, while all other minerals
are in isotopic disequilibrium. These magmas mixed prior
to and during the Campanian Ignimbrite eruption and
minerals were freely exchanged between the magma batches.
Combining the results of the geochemical investigations on
magma end-members with geophysical and geological data,
we develop the following scenario. In stage 1, a parental,
less differentiated magma rose into the middle crust, and evolved through combined crustal assimilation and crystal
fractionation. In stage 2, the differentiated magma rose to
shallower depth, fed the pre-Campanian Ignimbrite activity
and evolved by further open-system processes into the
most-evolved and most-radiogenic Campanian Ignimbrite
end-member magma. In stage 3, new trachytic magma, isotopically
distinct from the pre-Campanian Ignimbrite magmas,
rose from ca. 6 km to shallower depth, recharged the
most-evolved pre-Campanian Ignimbrite magma chamber,
and formed the large and stratified Campanian Ignimbrite
magmatic system. During the course of the Campanian
Ignimbrite eruption, the two layers were tapped separately
and/or simultaneously, and gave rise to the range of chemical
and isotopic values displayed by the Campanian Ignimbrite
pumices, glasses and minerals.
Description:
Published
Description:
285-300
Description:
2.3. TTC - Laboratori di chimica e fisica delle rocce
Description:
3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
Description:
JCR Journal
Description:
reserved
Keywords:
Campanian Ignimbrite
;
Radiogenic isotopes
;
Mixing process
;
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
;
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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