OSSERVATORIO VESUVIANO INGV NAPOLI

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• OSSERVATORIO VESUVIANO- INGV NAPOLI

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OV - Research Unit

• Lucia Civetta
• Giovanni Orsi
• Massimo DAntonio
• Mauro Di Vito
• Marixtel Aulinal y Junta
• Laura Font Morales
• Valeria Di Renzo
• Ilenia Arienzo

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Deliverables.

• workpackage 3 (Vesuvius-Campi Flegrei).
• workpackage 6 ( Magma Storage conditions rates
  and residence times) .
• workpackage 7 (Magma Storage conditions mineral
  equilibria studies).
• workpackage 8 (Magma systems analysis).
• To achieve these objectives we have studied the
  activity of Somma-Vesuvius, dated between ca.
  100 and 15 ka, and the Mercato (8 ka), Pollena
  (472 AD) and 1944 AD eruptions. and the Campi
  Flegrei eruptions Campanian Ignimbrite (39ka),
  Agnano Pomici Principali (10.3 ka), Astroni
  (4.1-3.7 ka) and Averno 2 (3.7 ka).

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Mantle source, differentiation and magmatic
structures of Campi Flegrei and Vesuvius
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• Campi Flegrei caldera and Vesuvius
• Objectives
• Identification of the primary magmas (genesis and
  differentiation)
• Differentiation processes operating in the
  magmatic system in the past 100 ka,
  mixing/mingling processes, crustal
  contamination
• Estimation of T, P and residence time of the
  magma present in the chamber at the time of
  significant eruptions, definition of the
  relationships between eruption and magma chamber
  tapping dynamics Modelling of the present state
  of the Phlegraean magmatic system using all the
  collected data.

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• The magmas of the Campi Flegrei rise through a
  thinned continental lithosphere as a consequence
  of the extension of the Tyrrhenian Basin.
• The present subduction of the oceanic Ionian
  plate is NW directed, while the continental Adria
  plate is SW directed.

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The Campi Flegrei volcanism

• Volcanic activity at Campi Flegrei started more
  than 60 ka BP.
• Campi Flegrei is a nested caldera formed during
  two main eruptions occurred at 39 ka (Campanian
  Ignimbrite ) and 15 ka BP (Neapolitan Yellow Tuff
  ).
• After the NYT eruption, volcanic activity
  continued with 72 eruptions, whose vents were
  located either along the marginal faults or
  within the floor of the NYT caldera.
• The last eruption generated the Mt. Nuovo tuff
  cone in 1538 AD.

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Chronogram of the Campi Flegrei caldera activity
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Campi Flegrei caldera Distribution of the vents
active in the past 14 ka
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Samples classification.
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Solchiaro and Minopoli 2
On the bases of the solubility model of Newman
Lowenstern (2002), using the H2O and CO2
contents of the inclusions, the minimum pressures
of crystallization have been calculated. The
pressure values calculated of about 200-400MPa
suggest the occurance of crystallization
reservoirs at a depth gt 8km.

• Cecchetti et al., 2004

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Campanian Ignimbrite
The majority of the studied inclusions were
formed between 20-60 MPa the higher H2O content
of some inclusions suggests crystallization
pressure of 100-140 MPa.

• Marianelli et al., 2004

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Astroni
The H2O content of MI correspond to saturation
pressures lower than 60 MPa.

• Cecchetti et al., 2004

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The Campanian Ignimbrite magmatic system.

• I. Arienzo1, A. Heumann3, L. Civetta1,2,
  G.Worner3
• 1.Osservatorio Vesuviano-
• 2.Università di Napoli Federico II
• 3.George August Universitat

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Our investigations are focused on

• investigate the magmatic processes occurred in
  the Campanian Ignimbrite (eruption age 39.28 /-
  0.11ka) magmatic system
• Investigate the timescale of these processes and
  the magma residence time.

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Campanian Ignimbrite-39 ka
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Samples classification.
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Zr/Sr vs DI
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SiO2 vs Major elements
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SiO2 vs trace elements
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REE patternsnormalizing chondrite values Boynton
1984
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Mass Balance
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87Sr/86Sr for minerals and whole rocks
87Sr/86Sr
Standard Sr NBS 987 0.707263/-6
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All the Campanian Ignimbrite products investigated
equiline
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S.Marco single pumice
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S.Marco white pumices
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S.Marco black pumices
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Mondragone 15U3 U.U.
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Isoplot 3

• If the probability to fit is more than 15 the
  assigned errors are considered the only reason
  for the data points scatter from the straight
  line
• The points are therefore weighted proportional to
  the inverse square of these errors
• The Mean Square of Weighted Deviates is roughly a
  measure of the ratio of the observed scatter of
  the points (from the best-fit line) to the
  expected scatter (from the assigned errors and
  error correlations)
• If the assigned errors are the only cause of
  scatter, the MSWD will tend to be near unity

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Pomici Principali
14C age 10,320 50 y
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Pomici Principali (10.3 ka) Chemostratigraphy
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Pomici Principali (10.3 ka) Chemostratigraphy
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Chemostratigraphy of theAgnano Monte Spina
products
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Astroni
14C age 3,800 50 y
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Chemostratigraphy of the Astroni products
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Chemostratigraphy of the Astroni products
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The Astroni activityIsotopic characteristics
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d11B vs. 87Sr/86Sr of the Astroni products
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The Astroni activity - Isotopic disequilibria
0.7078
87
86
Sr/
Sr
0.7075
0.70750
0.70738
0.70734
0.70733
0.7073
0.7070
348 6cd
348 7asc
348 L
0.7068
308 4a
0.70665
350 RT
0.7065
WR
SAN
BIOT
Dark Cpx
Light Cpx
Glass
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Astroni Conclusions
- Distinct populations of cpx- Distinct glass
compositions- Co-variation of Sr-, Nd-, and
B-isotopes suggestat least three distinct
magmatic components involved in the Phlegrean
magmatic system during the Astroni activity.
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Chemostratigraphy of the Averno 2 (3.8ka)
products
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Averno Conclusions

• The peculiarity of the Averno 2 eruption was the
  peralkaline character of the feeding magma. This
  peculiarity is shared only by this and two more
  eruptions occurred in the last 5 ka in the NW
  sector of the most uplifted portion of the
  resurgent block in the Campi Flegrei caldera.
  This relationship suggests that in this sector of
  the resurgent block, which is under a
  compressional stress regime, there are the
  conditions for small pockets of alkali-trachitic
  magma to stagnate at very shallow depth for times
  long enough to drive the composition towards
  peralkalinity.
• Moreover, the change of geochemical and
  isotopical features of the erupted magma, during
  the course of the eruption, suggests
  relationships among structural setting, magma
  composition and its variations, even in a very
  small magmatic system.

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87Sr/86Sr vs. age of eruption (Campi Flegrei)
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87Sr/86Sr vs. time Ischia, Procida and Campi
Flegrei
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87Sr/86Sr and 143Nd/144Nd vs D.I. for
Ischia, Procida, Campi Flegrei
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206Pb/204Pb and d11B vs D.I.
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Sr-Nd-B-Pb isotopic relationships in the PVD
The results of Sr-Nd-Pb-B isotopes study allow us
to define three components crust, fluid/melt
derived from the subducted slab and
asthenospheric mantle.
A progressive source contamination by fluids from
W to E can explain the isotopic variation of
trend A
Crustal contamination can explain the isotopic
signature of the younger than 39 ka CF magmas.
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Trace elements vs D.I. for Ischia, Procida and
Campi Flegrei
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Trace elements vs D.I. for Ischia, Procida and
Campi Flegrei
D.I.
D.I.
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87Sr/86Sr vs trace element ratios for Ischia,
Procida and Campi Flegrei
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Sr and B isotopes for PVD, Eolian Islands and Etna
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EC-AFC modelling of younger than 39ka Campi
Flegrei magmas
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• 
  Conclusions
• The CF magmas formed in a mantle source,
  metasomatised by fluids/melts deriving from
  sediments of the subducting slab.
• Different degrees of source enrichement by
  slab-derived fluids and/or partial melts, were
  idendified by comparing Ischia, Procida, Campi
  Flegrei, with a l progression from W to E.
• Data suggest that the CF magmatic system includes
  deep and shallow reservoirs. In the deep
  reservoir, magmas stagnate, differentiate and, in
  the last 39ka, are contaminated by crust and, in
  turn, feed shallow reservoirs. located at lt 2-3
  km of depth
• After the NYT eruption, the shallow reservoirs
  have been the site of both mixing/mingling
  processes among isotopically distinct components
  and trapping of xenocrysts remnant of earlier
  magmas. These processes have generated high
  heterogeneity and isotopic disequilibria in the
  erupted magmas. They are more pronounced for the
  magmas erupted erupted in the eastern portion of
  the caldera.
• Among the components involved in the
  mixing/mingling processes, together with new
  magma batches rising from the deep reservoir,
  there are always some which can be interpreted as
  residues of older than CI , CI, and NYT magmas.

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Vesuvius chronogram
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Mercato eruption (8ka) classification
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Mercato (8ka) chemostratigraphy
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Mercato (8ka) and Avellino (3.76ka)
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Mercato (8ka) chemostratigraphy
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Pollena (472 AD) classification
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Pollena (472AD) chemostratigraphy
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Pollena (472 AD) isotopic disequilibria
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The End