Publication Date:
2017-04-04
Description:
To develop a model of both the structure and evolution of the Campi Flegrei caldera (CFc) magmatic feeding
system, geochronological, geochemical and Sr, Nd, Pb and B isotopic data of representative volcanic products
of the past 15 ka have been combined with geophysical and melt inclusion literature data, structural setting
and dynamics of the resurgent caldera.
According to previous petrological data, the CFc magmatic feeding system consists of a deep reservoir, in which
mantle-derived K-basaltic parental magmas differentiate to shoshonite, latite and trachyte, through combined
crustal contamination and fractional crystallization processes, and shallowreservoirswhere the evolvedmagmas
further differentiate andmingle/mix before eruptions. The Sr,Nd, Pb, and B isotope data allowrecognition of three
distinctmagmatic components.One component is believedto be residualmagmafromtheNeapolitanYellowTuff
(NYT) caldera forming eruption. The NYT component (87Sr/86Sr of 0.70750–53, 143Nd/144Nd ratio of ca. 0.51246,
206Pb/204Pb of ca. 19.04 and δ11B of ca. –7.9‰), has been the most prevalent component over the past 15 ka being
mixed, in most cases, with the other two components. One of these other components is best recognized in the
Minopoli 2 magma, first erupted 10 ka ago. Minopoli 2 magma is shoshonitic in composition and is the most
enriched in radiogenic Sr (87Sr/86Sr of ca. 0.70860) and unradiogenic Nd and Pb (143Nd/144Nd ratio of ca. 0.51236,
206Pb/204Pb of ca. 18.90), and is characterised by δ11B value of ca. –7.32‰. The third component is trachytic in
composition and has higher 206Pb/204Pb (ca. 19.08), lower 87Sr/86Sr (ca. 0.70726) and δ11B (−9.8‰) and higher
143Nd/144Nd (ca. 0.51250), with respect to the NYT component. This third component is best recognized in the
Astroni 6 magma and did not appear until ca. 4 ka.
The identified isotopically distinct magmatic components were erupted in different sectors of the CFc. During
both I (b14.9–9.5 ka) and II (8.6–8.2 ka) epochs of volcanic activity,magmas similar to the NYT component, and
those resulting from mixing between Minopoli 2 and NYT components were erupted from vents located mostly
on the marginal faults of the NYT caldera. During the III epoch (4.8–3.8 ka) magmas either similar to NYT, or
resulting from mixing between Astroni 6 and NYT components were erupted from vents located along faults
bordering the La Starza resurgent block and, subordinately, the NYT caldera. Moreover, magmas resulting from
mixing betweenMinopoli 2 and NYT components were erupted fromvents located along NE–SW regional faults
activated during caldera resurgence.
The inferred present structure of the feeding system is characterised by a deep reservoir, whose top is at about
8 kmdepth, that hosts shoshonitic–trachyticmagmas. Remnants of the NYT magma reside at shallower depth in
different sectors of the crust underlying CFc, and were sometimes intercepted by volatile-rich magmas of deep
provenance during the three epochs of CFc volcanic activity.
Description:
Published
Description:
227-241
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:
Campi Flegrei caldera
;
Magmatic system
;
Caldera structure
;
Geochemistry
;
Isotopes
;
04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry
;
04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
;
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
