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Volcanism in the Campania Plain:
Vesuvius, Campi Flegrei and Ignimbrites
edited by B. De Vivo
© 2006 Elsevier B.V. All rights reserved.
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Chapter 9
The magma feeding system of Somma-Vesuvius (Italy)
strato-volcano: new inferences from a review of geochemical
and Sr, Nd, Pb and O isotope data
Monica Piochia,∗, Benedetto De Vivob and Robert A. Ayusoc
a
Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy
Dipartimento di Geofisica e Vulcanologia, Università Federico II, Napoli, Italy
c
U.S. Geological Survey, MS 954 National Center, Reston, VA, USA
b
Abstract
A large database of major, trace and isotope (Sr, Nd, Pb, O) data exists for rocks produced by the volcanic activity
of Somma-Vesuvius volcano. Variation diagrams strongly suggest a major role for evolutionary processes such
as fractional crystallization, contamination, crystal trapping and magma mixing, occurring after magma genesis
in the mantle. Most mafic magmas are enriched in LILE (K, Rb, Ba), REE (Ce, Sm) and Y, show small Nb–Ta
negative anomalies, and have values of Nb/Zr at about 0.15. Enrichments in LILE, REE, Nb and Ta do not
correlate with Sr isotope values or degree of both K enrichment and silica undersaturation. The results indicate
mantle source heterogeneity produced by slab-derived components beneath the volcano. However, the Sr isotope
values of Somma-Vesuvius increase from 0.7071 up to 0.7081 with transport through the uppermost 11–12 km
of the crust. The Sr isotope variation suggests that the crustal component affected the magmas during ascent
through the lithosphere to the surface. Our new geochemical assessment based on chemical, isotopic and fluid
inclusion data points to the existence of three main levels of magma storage. Two of the levels are deep and may
represent long-lived reservoirs, and an uppermost crustal level that probably coincides with the volcanic conduit.
The deeper level of magma storage is deeper than 12 km and fed the 1944 AD eruption. The intermediate level
coincides with the seismic discontinuity detected by Zollo et al. (1996) at about 8 km. This intermediate level
supplies magmas with 87Sr/86Sr values between 0.7071 and 0.7074, and δO18 ⬍8‰ that typically erupted both
during interplinian (i.e. 1906 AD) and sub-plinian (472 AD, 1631 AD) events. The shallowest level of magma storage at about 5 km was the site of magma chambers for the Pompei and Avellino eruptions. New investigations
are necessary to verify the proposed magma feeding system.
1. Introduction
Somma-Vesuvius (Fig. 1a) has long attracted intense scrutiny because of its recent activity,
enormous hazard potential to the Campanian region and immediate proximity to the city of
Naples. Plinian eruptions from the Somma-Vesuvius volcano were first described during
the eruption of 79 AD. The erupted silica-undersaturated potassium-rich rocks have been the
object of petrological studies (Rittmann, 1933; Savelli, 1967; Cortini and Hermes, 1981;
Joron et al., 1987; Civetta and Santacroce, 1992; Belkin et al., 1993; Cioni et al., 1995,
1998; Ayuso et al., 1998; Cioni, 2000; Peccerillo, 2001; Paone, 2005; Piochi et al., 2005;
*Corresponding author. Fax: 139-81-6100811. E-mail address: [email protected] (M. Piochi).
AQ1
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M. Piochi, B. De Vivo, R.A. Ayuso
and references therein) aimed at evaluating how the erupted magmas reflect the contributions of mantle sources, how their compositions have been affected during transport, and to
what extent they can be used to deduce their geodynamic setting. Recently, a large major,
trace and isotope (Sr, Nd, Pb, O) database has been published (De Vivo et al., 2003) and can
be downloaded at the Internet site http://www.dgv.unina.it/ricerca/de_vivo.htm. The
summary of results shows that rocks produced during major plinian and sub-plinian
eruptions, and during the last interplinian period of activity which started in 1631 AD, are
relatively well characterized on the basis of mineralogy, chemistry and isotopes. Adequate
data also exist for some rocks from interplinian periods of volcanism occurring before the
last sub-plinian eruption in 1631 AD.
In this paper, we briefly present a description of the chemical and isotopic database and
a synthesis of previous petrological studies in order to summarize the main evidence for
mantle source heterogeneity associated with the Somma-Vesuvius magmas, and highlight
the results supporting the importance of shallow-level evolution. Particularly, our brief
review of existing data points to a magma feeding system formed by multi-depth storage
levels; the magma reservoir at 8 km imaged by seismic tomography (Zollo et al., 1996) fed
both low- and large-magnitude eruptions. Significant progress has been made in the last
20 years of research focused on Somma-Vesuvius volcano (Civetta and Santacroce, 1992;
Belkin et al., 1993; Villemant et al., 1993; Cioni et al., 1995; Ayuso et al., 1998; Del Moro
et al., 2001; Peccerillo, 2001; Fulignati et al., 2004, 2005; Pappalardo et al., 2004; Piochi
et al., 2005), and it is now possible to combine the results of previous studies to produce a
framework for more detailed investigations of the behaviour of magma and the magma
feeding system in Somma-Vesuvius volcano.
2. Volcanological and magmatological background
Somma-Vesuvius is a strato-volcano (Fig. 1a) that consists of an older collapsed edifice
(Somma), and a younger cone (Vesuvius). The volcano has been active at least since 300 ky
bp (Brocchini et al., 2001 and references therein) up to the major eruption of 1944 AD.
Presently, the volcano is the site of fumaroles, diffuse degassing (Chiodini et al., 2001;
Federico et al., 2002; Frondini et al., 2004) and low-magnitude seismicity (Bianco et al.,
1999; Vilardo et al., 1999). Volcanism has been characterized by high explosive sub-plinian
and plinian eruptions that followed long periods of quiescence, and by intermediate and
small-scale explosive and explosive/effusive eruptions that occurred during continuous
periods of activity (interplinian period) (Fig. 1b) (Arnò et al., 1987; Civetta and Santacroce,
1992; Rolandi et al., 1998; Principe et al., 2004). Sub-plinian and plinian eruptions have
always produced larger volumes of rocks (one to a few cubic kilometres DRE, i.e. Dense
Rock Equivalent) (Rosi and Santacroce, 1983; Arnò et al., 1987; Civetta and Santacroce,
1992; Rolandi et al., 1993; Cioni et al., 1995; Landi et al., 1999) than the intermediate and
small-scale events (0.01–0.1 km3 DRE) (Scandone et al., 1986; Mastrolorenzo et al., 1993;
Rolandi et al., 1998; Arrighi et al., 2001).
The volcano rests on a sequence of Mesozoic and Cenozoic carbonates overlain by
Miocene sediments outcropping in the surrounding Apennine chain (D’Argenio et al.,
1973; Ippolito et al., 1975) and encountered at a depth of around 2 km (Brocchini et al.,
2001). The Moho discontinuity has been detected at about 30 km of depth (Corrado and
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The magma feeding system of Somma-Vesuvius (Italy) strato-volcano
Plinian Activity
Inter-Plinian Activity
Repose time ??
A.D.1944
III cycle
Recent
A.D.1631
Repose time
Medieval
II cycle
Transitional
A.D.472
(Pollena)
I cycle
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9th (1783-1794)
8th (1770-1779)
7th (1764-1767)
5th (1712-1737)
4th (1700-1707)
3rd (1696-1698)
2nd (1685-1694)
1st (1638-1682)
18th (1907-1944)
17th (1874-1906)
16th (1870-1872)
15th (1864-1868)
14th (1854-1861)
13th (1841-1850)
12th (1835-1839)
11th (1825-1834)
10th (1700-1707)
A.D.1139
2nd ( A.D.~635)
1st (>A.D. 512)
4th(~A.D.1095.)
3rd (>A.D.893.)
Repose time
A.D.303
Ancient Historic
A.D.79
Pompei
3.5 ky.B.P.
Avellino
8.0 ky.B.P.
Ottaviano (Mercato)
Repose time
800 years
Protohistoric
No geochronologic determinations
B.C.700
1st (~1758B.C.) 2nd (~1414 B.P) 3rd (~832 B.C.)
Repose time
6000 years
16-14 ky.B.P.
Novelle (Verdoline)
18.6 ky.B.P.
Sarno (Pomici di Base)
25.0 ky.B.P.
Codola
Somma
Older
Vesuvius
Somma activity
b)
a)
Figure 1. (a) DTM of the Somma-Vesuvius strato-volcano; (b) Reconstructed stratigraphy of volcanic activity
during the last 25 ka. Source: Arnò et al. (1987); Arrighi et al. (2001); Ayuso et al. (1998); Landi et al. (1999);
Rolandi et al. (1993, 1998); Rosi and Santacroce (1983). Symbols as used in the following figures. Names of
eruptions in parenthesis are from Arnò et al. (1987).
Rapolla, 1981; Ferrucci et al., 1989; Chiarabba et al., 2005). A high-velocity body dipping
westward from 65 km down to 285 km was interpreted as a plate within the mantle
(De Natale et al., 2001). Furthermore, an active, large magma chamber is located at about
8–10 km (Zollo et al., 1996; Di Maio et al., 1998) and has been proposed to extend up to
30 km (De Natale et al., 2001). However, based on fluid and melt inclusion evidence,
magma storage is indicated at 3.5–5, 8–10 and ⬎ 12 km (Belkin et al., 1985; Belkin and
De Vivo, 1993; Cioni et al., 1998; Marianelli et al., 1999; Cioni, 2000; Lima et al., 2003).
At present, no geophysical evidence for magma chambers of significant lateral extension
has been found at ⬍ 8 km (Zollo et al., 1996; Di Maio et al., 1998). This may be due to
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M. Piochi, B. De Vivo, R.A. Ayuso
the fact that resolution for the method used in tomography investigations is “blind” for
magma chambers with lateral extension ⬍ 1 km.
3. Mineral, chemical and isotopic data: description and previous interpretations
3.1. Mineralogy and classification
Somma-Vesuvius volcanic rocks are poorly (lava) to highly (scoria to pumice) vesiculated,
and nearly aphyric (mostly in the plinian eruptions) to strongly porphyritic (up to 50%; in
472 AD eruption and in the products younger than 1631 AD) (Joron et al., 1987; Villemant
et al., 1993). Two rock types are generally distinguishable on the basis of occurrence of
leucite minerals. In leucite-free rocks, olivine and Mg-rich diopside, plagioclase, Fe-rich
diopside, K-feldspar, magnetite and biotite can also occur, depending on the degree of
evolution. Leucite-bearing rocks contain olivine, Fe-rich and Mg-poor diopside, plagioclase
and oxide, also depending on the degree of evolution. Apatite, amphibole, garnet, phlogopite and forsterite are present as accessory phases. Nepheline, as the only feldspathoid, and
scapolite have been occasionally recovered (e.g. 472 AD and Avellino rocks).
Feldspar (both K-feldspar and plagioclase) is the most abundant mineral phase in
leucite-free rocks, such as Avellino and Sarno (Pomici di Base) (Joron et al., 1987; Landi
et al., 1999), as well as in 79 AD leucite-bearing pumices (Cioni et al., 1998). Instead, diopside is the most common mineral in the products younger than 1631 AD, whose abundance
changes as function of the degree of vesicularity of rocks (Villemant et al., 1993).
Clinopyroxenes have compositions indicative of multiple stages of crystallization in the
upper (⬍ 10 km) crust (Trigila and De Benedetti, 1993; Marianelli et al., 1995). Olivines
from 1944 and 1906 AD eruptions show compositions similar to olivine from peridotite
(Marianelli et al., 1995) and high pressure (⬎ 400 MPa) of volatile entrapment (Marianelli
et al., 1999) indicative of very early stage of magma crystallization.
Metamorphosed carbonates, skarns, lavas, cumulates, hornfels, sub-volcanic igneous
rocks have been generally recovered as xenolith ejecta within pyroclastic deposits (Savelli,
1967; Barberi and Leoni, 1980; Hermes and Cornel, 1981; Belkin et al., 1985; Del Moro
et al., 2001; Gilg et al., 2001; Fulignati et al., 2004, 2005). Metamorphosed carbonate
ejecta are considered to be representative of the carbonate basement modified during
contact metamorphism under the pressure of 1500–2000 bars. Skarn xenoliths consist of
calc-silicate and carbonatic components and contain fassaitic pyroxene, forsterite (Fo⬎90),
spinel, calcite, phlogopite, nepheline, garnet, periclase, brucite, calcite, and dolomite. They
are considered as representative of the crystallizing margins of the magma chamber (Del
Moro et al., 2001; Gilg et al., 2001; Fulignati et al., 2004, 2005). However, these xenoliths
were also interpreted to represent highly metasomatized blocks of stopped carbonates
incorporated into the magma (Hermes and Cornell, 1981). Silicate melt inclusions from
skarns show homogenization temperatures (Th) of 1000 ⫾ 50°C and trapping pressures
between 925 and 3550 bars (Belkin et al., 1985; Fulignati et al., 2004). Hornfels are
characterized by rhyolitic vesiculated glass and minerals of wollastonite, anorthite, calcite,
pyroxene and quartz, and have been considered the products of high-grade thermometamorphism from marly siltite rocks (Del Moro et al., 2001; Fulignati et al., 2005).
Cumulates are dunites, wherlites and biotite-bearing pyroxenites (Joron et al., 1987; Belkin
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and De Vivo, 1993). The cumulus phases are clinopyroxene, phlogopite, biotite, apatite,
plagioclase and olivine with Fo80–90; glass also occurs between individual crystal grains or
within cavities. Leucite is rare in cumulate nodules. Spinel and chromite can occur as
accessory phases. Th and trapping pressure of silicate melt inclusions in cumulates are
1200 ⫾ 50°C and in the range 1200–3050 bars, respectively (Belkin et al., 1985).
3.2. Major and trace elements
It is well known that rocks from Somma-Vesuvius are characterized by large compositional
variations. These rocks show variable alkali contents (Fig. 2a), and, in particular, show
variable degree of K2O enrichment. These rocks are slightly, mildly and highly silica
undersaturated, following Peccerillo (2003). Slightly silica-undersaturated volcanic rocks
are leucite-free and range in composition from shoshonites to trachy-phonolites; mildly to
highly undersaturated, nepheline- or, more commonly, leucite-bearing rocks, range from
alkali-basalt to phonolite.
Plinian and sub-plinian deposits are generally characterized by the most evolved compositions and chemical gradients through the stratigraphic sequence. The basal part of
deposits (white pumices) always shows the more sialic compositions, and the evolution
degree decreases upwards (grey pumices) (Arnò et al., 1987; Civetta et al., 1991; Civetta
and Santacroce, 1992; Rolandi et al., 1993; Cioni et al., 1995; Landi et al., 1999). These
features possibly reflect the progressive withdrawal of a chemically (and density) stratified
magma chamber located at shallow depth beneath the volcano. The variable layers can be
linked through simple chemical differentiation of unique parental magma (Landi et al.,
1999) or can be generated due to the arrival of diverse magma batches from deeper
reservoirs (e.g. Civetta et al., 1991; Cioni, 2000). Sometimes, the occurrence of products
with compositions intermediate between that of the different layers indicates syn-eruptive
mingling of magmas or the existence of a double-diffusive interface between the two magmatic layers within the magma chamber (Landi et al., 1999).
Because of the occurrence of carbonate and metamorphic ejecta (see previous section),
it has been suggested that plinian and sub-plinian chambers formed within the carbonate
basement, between 5 and 8 km depth (Barberi and Leoni, 1980; Belkin and De Vivo, 1993;
Landi et al., 1999; Cioni, 2000) during the long time of quiescence that precedes the
eruption (Fig. 1b) and that allows reaching the high evolution degree of these rocks.
Magmas erupted during interplinian periods are characterized by low degree of evolution
(Fig. 2) and depths of storage at ⬍ 5 km, 8–10 km and ⬎ 12 km (Belkin et al., 1985; Belkin
and De Vivo, 1993; Cioni et al., 1998; Marianelli et al., 1999; Cioni, 2000; Lima et al.,
2003). Owing to the occurrence of deeply crystallized olivines (see previous section), the
existence of CO2-bearing melt inclusions and the brief repose time between two eruptions
(not more than 7 years) (Arnò et al., 1987), the various authors indicate that during
interplinian periods magmas can rapidly rise to the surface in open-conduit conditions. The
last 1944 AD eruption was fed by a magma directly rising from a depth of ⬎ 12 km. After
61 years of volcanic quiet, this latter eruption probably closes the third, last mega-cycle of
volcanism (Ayuso et al., 1998) and marks the transition to the closed-conduit condition
(Rosi et al., 1987). This situation of repose might last for centuries, heading towards the
starting of new, fourth, mega-cycle of volcanism, with a new plinian–sub-plinian eruption
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Na2O+K2O (wt%)
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Phonolite
Tephriphonolite
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a)
Trachyte
PhonoTephrite
Trachybasalt
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Latite
Trachy- Trachydacite
andesite
Foidite Tephrite
Basanite
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andesite
Andesite
Dacite
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MgO (wt%)
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9
Figure 2. (a) T.A.S. (Le Bas et al., 1986); (b) Sr versus SiO2 contents; and (c) La versus MgO for SV rocks.
Symbols as in Figure 1: bold crosses are dykes from Somma activity; closed symbols are rocks from plinian and
sub-plinian events; and open symbols rocks from interplinian periods. Circles, first magmatic cycle; rhombus,
second magmatic cycle; triangles, transitional magmatic cycle; squares, third magmatic cycle. Source: Cioni
et al. (1995); Civetta et al. (1991); Civetta and Santacroce (1992); De Vivo et al. (2003); Marianelli et al. (1999);
Santacroce et al. (1993).
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(Lima et al., 2003). In this context, to predict the behaviour of the volcano, acquiring a better understanding of magma evolution processes, of the magma feeding system, and of the
precise role of the volatiles are crucial (Raia et al., 2000; Webster et al., 2001, 2003, 2005).
In many studies, SiO2 or MgO have been utilized as differentiation indices. Variations
in SiO2 seem to adequately illustrate the evolution of intermediate-to-most fractionated
rocks (Fig. 2b), but not the least-fractionated rocks. In contrast, MgO, appears more
adequate for the least-fractionated rocks (Fig. 2c). In any case, based on major and trace
elements variations (Fig. 2a–c), diverse evolutionary trends characterized by variable K, P,
Ti, some trace elements (i.e. Th, U, Sr) and LREE enrichment have been found (Joron
et al., 1987; Ayuso et al., 1998; Piochi et al., 2005). Within each trend, the role of crystal
fractionation processes in magma evolution has been widely accepted (Joron et al., 1987;
Civetta et al., 1991; Ayuso et al., 1998; Piochi et al., 2005 and references therein).
Feldspar and clinopyroxene are the main crystallizing minerals, in agreement with
petrographic data reported in previous section. Chemical trends in Sr and CaO/Al2O3 versus
K2O diagrams (Fig. 3a,b) suggest clinopyroxene associated with feldspar (mostly plagioclase and subordinately K-feldspar) crystallization during evolution of magmas older than
472 AD eruption (Piochi et al., 2005). The Sr versus Th diagram (Fig. 3c) highlights plagioclase fractionation. In contrast, clinopyroxene crystallization dominated during evolution of
highly undersaturated magmas of the post-1631 AD interplinian period, as also suggested by
Belkin et al. (1993), Villemant et al. (1993) and Trigila and De Benedetti (1993). In these
younger rocks, the variable abundance of clinopyroxene affects major- and REE-elements
variation (Belkin et al., 1993; Villemant et al., 1993). REE showing fairly homogeneous
patterns and variable LREE enrichment support the above data. In particular, the Eu anomaly is not a typical feature of primary magmas from Somma-Vesuvius. It seems to be
correlated with the degree of evolution; it is mostly present in highly evolved rocks, such as
79 AD, Avellino, and probably reflects feldspar fractionation (Joron et al., 1987).
In the MORB- and OIB-multi-elements normalized diagrams (Fig. 4a,b) rocks from
Somma-Vesuvius show similar trace elements distribution, regardless of the degree of silica
undersaturation and K enrichment. The least evolved rocks (MgO ⬎ 3 wt%) are characterized by high LILE (Rb, Ba, Th, K) and slight HFSE (Zr, Nb) enrichment, and slight Nb and
Ta trough with respect to MORB (Fig. 4a), similarly to other potassic magmas (Peccerillo
and Manetti, 1985; Peccerillo, 2001, 2003). Furthermore, these rocks have higher Cs, K, Pb,
Rb, Th, Ba and lower Nb and Ti contents compared to OIB (Fig. 4b). A heterogeneous
mantle source(s) has been therefore proposed to explain the variable undersaturation degree
of the rocks and, in particular, the occurrence of different parental magmas and different
evolutionary trends as shown in Figure 2 (Civetta et al., 1991; Civetta and Santacroce, 1992;
Ayuso et al., 1998; Piochi et al., 2005). Other authors (Rittmann, 1933; Pappalardo et al.,
2004; Piochi et al., 2005) have also speculated that crustal contamination processes
contributed to the enrichment in K and in various other trace elements.
3.3. Sr, Nd, Pb, Hf, O and He isotope ratios
The variable silica-undersaturated Somma-Vesuvius volcanic rocks show similar range of Sr,
Nd, Pb and O isotopic compositions, with large variability within each cycle. 87Sr/86Sr
isotopic values span from 0.706283 to 0.708070 (Cortini and Hermes, 1981; Civetta and
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a)
cp
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x
+c
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fel
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0
0.0
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400
Th (ppm)
0
0
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80
100
Figure 3. (a) Sr versus Al2O3; (b) Sr versus K2O; and (c) Sr versus Th contents for Somma-Vesuvius rocks.
Symbols and source of data as in Figure 2.
Santacroce, 1992; Caprarelli et al., 1993; Cioni et al., 1995; Ayuso et al., 1998; De Vivo
et al., 2003; Piochi et al., 2005). The 143Nd/144Nd values range from 0.51225 to 0.51226
(Fig. 5a). Pb isotopic compositions have a moderate variation (Fig. 5b): 206Pb/204Pb values
vary from 18.94 to 19.09, 208Pb/204Pb from 38.7 to 39.3 and 207Pb/204Pb from 15.61 to 15.71
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.1
Cs Rb Ba Th U Nb K La Ce Pb Pr Sr P Nd Zr Sm Eu Ti Dy Y Yb Lu
Figure 4. Spider diagrams for selected Somma-Vesuvius rocks with MgO ⬎ 3 wt%. Source of data and
symbols as in Figure 2.
(Somma et al., 2001; De Vivo et al., 2003; Cortini et al., 2004). Pb isotope variations are not
correlated to Sr and Nd isotope variations. δO18 values obtained on whole-rocks range from
7.5% to 10‰, showing no correlation with Nd and Pb isotopic compositions, and defines no
typical correlation with the 87Sr/86Sr ratio (Fig. 5c) (Wilson, 1989). Among the isotopes, only
δO18 correlates (positively) with degree of chemical evolution (Fig. 6a,b). He isotope composition is about 2.4 Ra (where Ra is the 3He/4He of the atmosphere equal to 1.40 ⫻ 10−6)
(Graham et al., 1993) for 1944 AD olivines and pyroxenes, indicating a source within the
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Figure 5. Isotopic diagrams for Somma-Vesuvius rocks: (a) 87Sr/86Sr versus 143Nd/144Nd ratios; (b) 208Pb/204Pb
versus 206Pb/204Pb; and (c) δO18 versus 87Sr/86Sr ratio. Symbols and source of data as in Figure 2.
lithospheric or in a slab-enriched mantle source. Similar He-isotopic values have been measured in fumarole gases suggesting a magmatic contribution to the degassing observed at the
surface (Graham et al., 1993). 176Hf/177Hf ratios determined on two Somma-Vesuvius rocks
characterized by Sr isotopic values lower than 0.7072 are 0.282784 and 0.282786, suggesting a pelagic component added to HIMU and DM mantle sources (Gasperini et al., 2002).
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The Sr isotope compositions of products from plinian and sub-plinian eruptions follow
a systematic trend through the stratigraphic sequence, consistent with the previously
recognized chemostratigraphy (see previous section) though to represent magmas residing
in a shallow and chemically stratified chamber (Civetta et al., 1991). For example, the
Avellino and the 79 AD pyroclastic sequences consist of white pumices, at the base, overlain by grey pumice deposits. White and grey pumices have different chemical and Sr isotope compositions. However, both pumice types contain feldspars with a constant Sr
isotopic composition, similar to that of white pumices, suggesting Sr isotopic disequilibrium in rocks upwards in the sequence and mingling of magmas during eruption.
Moreover, the lowermost part of the 79 AD eruption and the uppermost part of Avellino
have similar 87Sr/86Sr values, suggesting that magma remnants can be left behind within
the chamber after large magnitude events (Civetta et al., 1991; Civetta and Santacroce,
1992). Such a type of incomplete magma removal has also been suggested by evidence
showing that events following plinian or sub-plinian eruptions produced magmas that have
isotopic characteristics comparable to those of previous eruptions (Civetta and Santacroce,
1992; Piochi et al., 2005) (Fig. 7).
11
δO18
a)
b)
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7
7
0.0
0.2
0.4
0.6
0.8
1.0
CaO/Al2O3
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800
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Sr (ppm)
Figure 6. δO18 versus CaO/Al2O3 ratio (a) and Sr (b) for Somma-Vesuvius rocks. Lines indicate trend of magma
evolution. Symbols and source of data as in Figure 2.
0.7080
b)
87Sr/86Sr
0.7076
0.7072
0.7068
0.7064
0.7060
10
Figure 7.
87
100
1000
10000
Sr/86Sr versus age of rocks from Somma-Vesuvius. Symbols and source of data as in Figure 2.
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The 87Sr/86Sr isotopic variations have been attributed to the arrival of isotopically
diverse magma batches generated in a variable mantle source(s) (Cortini and Hermes,
1981; Civetta and Santacroce, 1992; Caprarelli et al., 1993; Cioni et al., 1995; Ayuso et al.,
1998; Piochi et al., 2005). Recently, as first recognized by Rittmann (1933), various
authors (Civetta et al., 2004; Pappalardo et al., 2004; Paone, 2005; Piochi et al., 2005)
suggested the fundamental role of crustal contamination in modifying the isotopic
composition of erupted magmas at Somma-Vesuvius. Civetta et al. (2004) and Paone
(2005) proposed that contamination occurred within a Hercynian-like basement, similarly
to what happens at the Campi Flegrei (Pappalardo et al., 2002). Pappalardo et al. (2004)
and Piochi et al. (2005) suggested that carbonate was the main contaminant. In particular,
based on Sr isotope variations through time, Pappalardo et al. (2004) suggested that
between 1631 and 1944 AD the degree of magma contamination decreased owing to
magma rising from a deep reservoir in open-conduit conditions.
4. Discussion
The relationship between magma compositions and tectonic setting depends on reliably
distinguishing among geochemical features that image the source region and those that
resulted from magma evolution during transport. Processes affecting magmas after their
genesis are important in characterizing the behaviour of the magmatic supply system. Such
processes, for example, fractional crystallization, can produce highly evolved magmas,
which when associated with long-lived magma storage in the crust can generate highmagnitude explosive events. Recharge of distinct magma batches from deeper levels within
the feeding reservoir may be required to trigger volcanic eruptions. Crustal contamination
requires chemical exchange between magma and wall rocks that can lead to fluid enrichment, increasing the possibility of highly explosive eruptions, or that can induce quick
cooling and/or crystallization of magma limiting its further mobility. Properly identifying
the exact mechanism of magma evolution, i.e. magma mixing or crustal contamination, can
be a useful tool for hazard assessment studies. For the Somma-Vesuvius volcano, it would
be important to determine to what extent the evolution of the magmas depend on involvement of the crust during magma genesis (with heterogeneously slab-enriched mantle
sources) or during magma evolution (Rittman, 1933; Savelli, 1967, 1968; Turi and Taylor,
1976; Vollmer, 1976; Civetta and Santacroce, 1992; Santacroce et al., 1993; Cioni et al.,
1995; Ayuso et al., 1998; Peccerillo, 2001; Pappalardo et al., 2004; Piochi et al., 2005), and
how the geochemical evolution exactly triggers sub-plinian and plinian eruptions.
4.1. The role of crustal component on magma composition
The role of the crust on magma composition at the Somma-Vesuvius volcano is suggested
from both mineralogical and compositional data. For example, phlogopite occurs among
mineral phases. Th/Yb is always higher than 2 (Peccerillo and Manetti, 1985; Peccerillo,
2001). Ce/Pb ratios, being significantly lower than those of mantle sources free of subduction influences (⬇ 25; Hofmann et al., 1986), tend towards the upper crustal value (⬇ 3.5;
Taylor and Mc Lennan, 1985). Similarly, Nb/U value mostly falls within the continental
crustal range (⬍ 12; Rudnick and Fountain, 1995) (Fig. 8).
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a)
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Figure 8. (a) 87Sr/86Sr versus Ce/Pb ratios; (b) 87Sr/86Sr versus Nb/U ratios; and (c) δO18 versus Ce/Pb ratios for
Somma-Vesuvius rocks. Symbols and source of data as in Figure 2.
In addition, the role of the crust is also suggested from Sr, Pb and O (as well as Hf)
isotope ratios. In fact, these isotope ratios, although highly scattered, show rough correlations with the above chemical ratios: Ce/Pb negatively correlates with 87Sr/86Sr and δO18,
Nb/U positively correlates with Sr isotope composition (Fig. 8a–c). These ratios do not
depend on the stage of evolution of the rocks because Ce and Pb, as well as Nb and U, show
almost comparable behaviour with respect to SiO2 or MgO, suggesting a similar partition
coefficient in the melt. The observed correlations can be attributed to the variable contributions of the crustal component to the magma.
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One important problem is to establish if the crustal component was involved at the time
of melting of the source or subsequently during ascent. Generally, radiogenic and stable
isotopes can be used to define the site at which contamination occurs. Nevertheless,
available O and Sr isotopic data do not conclusively provide information about input of
crustal materials/fluids to the magma (either in the mantle source or during shallow-levels
differentiation processes), although we know that higher O isotope compositions are found
in plinian-type rocks. Below we report some evidence that can be helpful to deal with this
fundamental question.
The generally low Mg, Ni and Cr (most values are ⬍ 40 and 100 ppm, respectively)
contents, and high crystallinity suggest the importance of processes occurring in magmas
during crustal storage and ascent. Chemical exchange processes between magmas and
carbonate wall rocks are indicated by garnet and phlogopite (Belkin et al., 1985; Joron
et al., 1987) and by Ca–Mg-silicate-rich ejecta (skarns) (Savelli, 1968; Fulignati et al.,
1995, 1998, 2005; Gilg et al., 1999, 2001; Del Moro et al., 2001). Oxygen isotope studies
(Turi and Taylor, 1976; Ayuso et al., 1998), U-disequilibria (Black et al., 1998) and Pb isotope data (Cortini et al., 2004) document shallow-level evolution of Somma-Vesuvius
magmas as open systems. Nevertheless, the strongest evidence for the dominating role of
shallow-level (crust) processes subsequent to high-pressure (mantle) processes derives
from a synthesis of Sr isotope and fluid inclusion data that suggests a positive correlation
between 87Sr/86Sr values and the estimated depths of mineral crystallization (Fig. 9). The
suggestion is that products enriched in radiogenic Sr formed during later stages of magma
evolution (Pappalardo et al., 2004).
The lower 87Sr/86Sr ratios (mostly around 0.7071–0.7072 with few spikes at
0.7062–0.7068) are associated with the highly silica-undersaturated rocks from the 1944 AD
eruption containing primitive olivine compositions (Marianelli et al., 1995). These ratios partially overlap the Campi Flegrei Sr-isotope range (0.7068–0.7086) (Pappalardo et al., 2002),
0
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14
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18
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0.7070
87Sr/86Sr
0.7074
0.7078
Figure 9. 87Sr/86Sr versus depth of crystallizing phases from SV rocks. Squares, clinopyroxene; rhombus,
feldspar; and triangles, leucite. Source of data as in Figure 2 (modified from Pappalardo et al. (2004). Grey areas
indicate probably levels of magma storage, based on fluid inclusion, volcanological and seismic data (see text).
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differ from values recovered at the nearby Procida (0.70523–0.70678) (De Astis
et al., 2004) and are higher than the Tyrrhenian Sea basalts (0.70733–0.7056) (Beccaluva
et al., 1990). In addition, they are associated with 176Hf/177Hf ratios of 0.282785 (two 1944 AD
samples reported in Gasperini et al., 2002) and He isotope ratio lower than MORB-like
magmas (Graham et al., 1993). Moreover, the 1944 AD eruption, and other rocks that are
generally poorly evolved (MgO ⬎ 3 wt%), are enriched in LILE, LREE and other incompatible trace elements (e.g. Th, Nb, Ta), as well as in more compatible elements such as HREE
and Y (Fig. 4a). These geochemical features are usually related to magmas erupted along
subduction zones, implying the involvement of a crustal component in the mantle source
beneath Somma-Vesuvius.
4.2. The mantle source
The least-evolved Somma-Vesuvius rocks (MgO ⬎ 3 wt%) belong to the within-plate
type in term of Zr (⬎ 100 ppm) and Zr/Y (⬎ 4) (Pearce and Norry, 1979) (Fig. 10), in
agreement with evidence from the multi-element normalized diagram (Fig. 4b) showing
a certain similarity to the OIB basalts. The positive correlation in Figure 10 points to a
decrease in degree of partial melting or (fluid-controlled) source heterogeneity. Based on
the Cs–Pb enrichment in Figure 4b, the LILE enrichment and the slight Nb–Ta negative
anomalies in Figure 4a, and Nb/Zr at about 0.15, as well as on the isotope features discussed in the previous section, we suggest that the mantle source of Somma-Vesuvius
contains a slab-derived component. This conclusion is consistent with the general idea
that enriched potassium-rich magmas are generated by partial melting of phlogopite-rich
garnet peridotite (Gupta and Fyfe, 2003).
Poorly evolved rocks (MgO ⬎ 3 wt%) with a high degree of silica undersaturation
show significant constancy of Th/Zr (0.05–0.08), Ta/Yb (0.7) and Cs/Rb (⬍ 0.06), as well
as Th/Yb, Th/Ta and other ratios, that are independent of fractional crystallization and/or
partial melting. These relatively unevolved rocks, as well as the slightly and mildly silicaundersaturated rocks, have comparable trace elements distributions, showing similar
Zr/Y
10
Phlegraean area
Vesuvius
Tyrrhenian sea
Zr (ppm)
1
100
1000
Figure 10. Zr and Zr/Y for SV rocks with MgO ⬎3 wt%. Source of data and symbols as in Figure 2. Data from
Phlegraean Fields (D’Antonio et al., 1999; Pappalardo et al., 1999; Piochi et al., 1999) and Tyrrhyenian Sea
(Beccaluva et al., 1990) are also reported for comparison.
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enrichment in LILE, Ce and other incompatible trace elements (e.g. Th, Nb, Ta), as well
as in more compatible elements such as Sm and Y (Fig. 4) independent of their Sr isotope
values and K-enrichment degree. Therefore, in a general sense, these data suggest the
existence of an invariable mantle source during the life of the Somma-Vesuvius volcano.
In agreement with Peccerillo and Manetti (1985), we suggest that diverse degrees of silica
undersaturation in potassic “mafic” rocks was linked to small degrees of partial melting
at different pressures in a phlogopite-bearing potassium-rich peridotitic mantle source
containing CO2 and small amounts of water. Sr, Nd, Pb, O, He and Hf isotopes were likely
affected by processes in the mantle source. However, with our hypothesis, the absence of
relationships between Sr–Nd isotope compositions and degree of both alkali enrichment
and silica undersaturation of “mafic” rocks suggests that mantle source processes mostly
influence the chemical composition of parental magmas, but it cannot be the main cause
of the large isotopic variability of Somma-Vesuvius rocks with 87Sr/86Sr ratios higher than
0.7071.
4.3. The behaviour of the magmatic feeding system
Based on the variation of the 87Sr/86Sr values, contamination of Somma-Vesuvius magmas
was attributed to a Hercynian-like basement (Civetta et al., 2004; Paone, 2005) or to rocks
in the overlying sedimentary series (Rittmann, 1933; Pappalardo et al., 2004; Piochi et al.,
2005). However, on the basis of data in Figure 9 we suggest that the increase in Sr isotope
values from 0.7071-3 to 0.7081 mostly occurs within the uppermost 11–12 km of the crust
and points to these sedimentary rocks as the main crustal contaminant. However, we cannot exclude that magma contamination could have occurred in crustal rocks underlying the
carbonate basement. We stress the fact that no xenolith of possible Hercynian origin has
been found at Somma-Vesuvius, contrary to what happened at the nearby Campi Flegrei
(Pappalardo et al., 2002; Paone, 2005).
Contamination of magma (87Sr/86Sr ⬇ 0.7071) by carbonate rocks (87Sr/86Sr ⬇
0.7073–00709; Sr ⫽ 700–1000 ppm) (Civetta et al., 1991; Iannace, 1991) at SommaVesuvius has been quantitatively modelled by Pappalardo et al. (2004) and Piochi et al.
(2005) who suggested that crustal contamination was a selective process involving thermal
decomposition (decarbonation reactions) of the sedimentary wall rocks and exchange
between magmas and fluids. Fulignati et al. (2004, 2005) also suggested similar conclusions on the basis of geochemical and mineralogical data collected on 79 and 1944 AD
skarn ejecta. We recognize, however, that magma evolution was likely more complicated
than as stated previously because no correlation has been found for δO18 and 87Sr/86Sr
values, and because of the negative correlation between phenocryst abundance and values
of 87Sr/86Sr (Figs. 5c and 11). Moreover, hornfels rhyolitic pumices characterized by
87
Sr/86Sr higher than 0.711 and δO18 at around 15‰ have been found among ejecta in various pyroclastic deposits and have been interpreted as the result of the partial melting of
the pelitic sediments during thermometamorphic event (Del Moro et al., 2001; Fulignati et
al., 2005). This fact suggests the possible involvement of Miocene sediments in addition
to carbonate during the evolution of magmas at the Somma-Vesuvius.
Fluid exchange between magmas and wall rocks could be more pervasive on magmas
associated with high-explosive eruptions. Available data reveal relatively high values and
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87Sr/86Sr
a)
0.7079
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% phenocrysts
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Figure 11. (a) 87Sr/86Sr versus phenocryst content in rocks from recent interplinian period of volcanism;
(b) 87Sr/86Sr versus age of rocks. Symbols and source of data as in Figure 2.
a large range of δO18 for pumices from plinian and sub-plinian eruptions, and relatively
low δO18 values and a smaller range for highly silica-undersaturated volcanic rocks from
interplinian events (Figs. 5c, and 6a,b). The correlation for δO18 and chemical differentiation indices (better defined for rocks from high-explosive eruptions), together with numerical considerations reported in Ayuso et al. (1998), data from Cortini et al. (2004) and the
observed enrichment in some incompatible trace elements (La, Nb, Zr) of pumices from
plinian eruptions (Fig. 2c), also support the effects of fluid exchange, rather than isotope
fractionation determined by exsolution of gas from magma.
Magmas erupted during the post-1631 AD interplinian period are characterized by the
decrease of the 87Sr/86Sr ratio with increasing phenocryst content down to typical values of
clinopyroxenite (⬍ 0.7071) (Del Moro et al., 2001). This relation can be attributed to (1) the
entrapment of crystal mush generated during previous magma storage in the crust by rising
magmas and/or (2) the accumulation/depletion of phenocrysts during magma movements
through the crust towards the surface. In the first case, magmatic melts should be characterized by higher 87Sr/86Sr ratios. Otherwise, phenocrysts can be accumulated or be depleted
in magma as a function of the ascent rate of magma towards the surface (see also Villemant
et al., 1993). In particular, low ascent rate can result in crystal segregation and in longer time
during which melt stay within wall rocks, thus producing rocks with lower crystal content
and possibly higher crustal contamination. This second hypothesis is in agreement with evidence from Villemant et al. (1993) indicating that lavas derived from magmas experiencing
volatile degassing generally contain lower crystal abundance than vesiculated fragments
generated by gas overpressure. This idea is supported by evidence that magmas with the
lowermost Sr isotope ratios erupted during the 1944 AD rose to the surface from 11–22 km
depth (Marianelli et al., 1999). However, the repetitive and regular variation of 87Sr/86Sr
values through time (Fig. 7) is consistent with the idea that residual magma or crystal mush
remaining in the magmatic system after the end of the plinian (or sub-plinian) eruptive
event, can be involved in subsequent eruptions (Civetta et al., 1991; Civetta and Santacroce,
1992; Cioni et al., 1995; Lima et al., 2003; Piochi et al., 2005).
87
Sr/86Sr, δO18 and fluid inclusion data strongly suggest polybaric evolutionary
processes of diverse parental magmas at Somma-Vesuvius. Evolutionary processes were
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dominated by crustal contamination and crystal entrapment, in addition to crystal fractionation and magma mixing. Evidence presented in this paper, in particular data shown in
Figure 9, allows us to speculate that magmas with 87Sr/86Sr ratios of around 0.7071-3 and
of 0.7074-5 derive from reservoirs probably located at different depths, i.e. ⬎ 12 km and
at around 8–12 km, respectively. Magmas with higher Sr isotope compositions, for example those from Pompei and Avellino eruptions, evolved during storage in shallower magma
chambers or, for example those from some of post-1631 AD interplinian eruptions, during
the ascent through the conduit.
5. Conclusions
Available data in the literature furnish the possibility to preliminarily define the magma
feeding system beneath the Somma-Vesuvius strato-volcano. It consists of three main
levels of magma storage, the two deepest probably being long-lived reservoirs, and an
uppermost crustal level that probably includes the volcanic conduit and hosted magmas
during interplinian period of volcanism. The deeper level is located at depths exceeding
15 km and should furnish magma with 87Sr/86Sr ratios of ⬍ 0.7072 and δO18 ⬍ 8‰. The
intermediate level occurs at around 8–12 km depth and supplies magmas with 87Sr/86Sr
ratios between 0.7071 and 0.7074, and δO18 ⬍ 8‰ typically erupted both during
interplinian (i.e. 1906 AD) and sub-plinian (472 AD, 1631 AD) events. The shallow level at
around 5 km depth was the site of plinian magma chambers such as those of Pompei and
Avellino eruptions. This type of magma feeding system fits with fluid and melt inclusions
data (Belkin et al., 1985; Belkin and De Vivo, 1993; Marianelli et al., 1999; Cioni, 2000;
Lima et al., 2003) indicating magma storage at 3.5–5 km, 8–10 km and ⬎ 12 km, with
results of seismic (Zollo et al., 1996) and magnetotelluric (Di Maio et al., 1998) investigations indicating a discontinuity at 8–10 km depth, with seismic evidence of deeper magma
storage extending up to 30 km depth (De Natale et al., 2001), and with the magnetized
character of a narrow shallow crustal volume (Fedi et al., 1998). However, geophysical data
do not indicate the occurrence of current magma storage at a depth of ⬍ 5 km,
as vice versa is indicated by fluid and melt inclusion studies (Belkin et al., 1985; Belkin
and De Vivo, 1993; Marianelli et al., 1999; Cioni, 2000; Lima et al., 2003).
Acknowledgements
The authors are thankful to A. Peccerillo for his constructive review, which helped to
improve the final version of the manuscript. The paper has benefited from MIUR-PRIN
funds to B. De Vivo (2003–2004).
References
Arnò, V., Principe, C., Rosi, M., Santacroce, R., Sbrana, A., Sheridan, M.F., 1987. Eruptive history. In:
Santacroce, R. (Ed.), Somma-Vesuvius, Quaderni de “La Ricerca Scientifica”, CNR, Italy, 251 pp.
Arrighi, S., Principe, C., Rosi, M., 2001. Violent strombolian and subplinian eruptions at Vesuvius during post1631 activity. Bull. Volcanol. 63, 126–150.
Else_DV-DEVIVO_ch009.qxd
3/2/2006
2:53 PM
Page 201
The magma feeding system of Somma-Vesuvius (Italy) strato-volcano
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
20
1
2
3
4
5
6
7
8
9
30
1
2
3
4
5
6
7
8
9
40
41
42
43
44
45
46
201
Ayuso, R.A., De Vivo, B., Rolandi, G., Seal II, R.R., Paone, A., 1998. Geochemical and isotopic (Nd-Pb-Sr-O)
variations bearing on the genesis of volcanic rocks from Vesuvius, Italy. J. Volcanol. Geotherm. Res. 82, 53–78.
Barberi, F., Leoni, L., 1980. Metamorphic carbonate ejecta from Vesuvius plinian eruptions: evidence of the
occurrence of shallow magma chambers. Bull. Volcanol. 43, 107–120.
Beccaluva, L., Di Girolamo, P., Morra, V., Siena, F., 1990. Phlegraean Fields volcanism revisited: a critical reexamination of deep-eruptive systems and magma evolutionary processes. N. Jb. Geol. Paleont. Mh. H5,
257–271.
Belkin, H.E., De Vivo, B., 1993. Fluid inclusion studies of ejected nodules from plinian eruptions of Mt. SommaVesuvius. J. Volcanol. Geotherm. Res. 58, 98–100.
Belkin, H.E., De Vivo, B., Roedder, E., Cortini, M., 1985. Fluid inclusion geobarometry from ejected
Mt. Somma-Vesuvius nodules. Am. Mineral. 70, 288–303.
Belkin, H.E., Kilburn, C.R.J., De Vivo, B., Trigila, R., 1993. Sampling and analytical chemistry of the recent
Vesuvius activity (1631–1944). J. Volcanol. Geotherm. Res. 58, 273–290.
Bianco, F., Castellano, M., Milano, G., Vilardo, G., Ferrucci, F., Gresta, S., 1999. The seismic crises at
Mt. Vesuvius during 1995 and 1996. Phys. Chem. Earth 24(111–112), 977–983.
Black, S., Macdonald, R., De Vivo, B., Kilburn, C.R.J., Rolandi, G., 1998. U-series disequilibria in young
(AD 1944) Vesuvius rocks, preliminary implications for magma residence times and volatile addition.
J. Volcanol. Geotherm. Res. 82, 97–111.
Brocchini, D., Principe, C., Castradori, D., Laurenzi, M.A., Gorla, L., 2001. Quaternary evolution of the southern
sector of the Campanian Plain and early Somma-Vesuvius activity: insights from the Trecase 1 well. Miner.
Petrol. 73, 67–91.
Caprarelli, G., Togashi, S., De Vivo, B., 1993. Preliminary Sr and Nd isotopic data for recent lavas from Vesuvius
volcano. J. Volcanol. Geotherm. Res. 58, 377–381.
Chiarabba, C., Jovane, L., Di Stefano, R., 2005. A new view of Italian seismicity using 20 years of instrumental
recordings. Tectonophysics 395, 251–268.
Chiodini, G., Marini, L., Russo, M., 2001. Geochemical evidence for the existence of high-temperature
hydrothermal brines at Vesuvio volcano, Italy. Geochim. Cosmochim. Acta 65, 2129–2147.
Cioni, R., 2000. Volatile content and degassing processes in the AD 79 magma chamber at Vesuvius (Italy).
Contrib. Mineral. Petrol. 140, 40–54.
Cioni, R., Civetta, L., Marianelli, P., Metrich, N., Santacroce, R., Sbrana, A., 1995. Compositional layering and
syn-eruptive mixing of a periodically refilled shallow magma chamber: the AD 79 plinian eruption of
Vesuvius. J. Petrol. 36, 739–776.
Cioni, R., Marianelli, P., Santacroce, R., 1998. Thermal and compositional evolution of the shallow magma chambers
of Vesuvius, evidence from pyroxene phenocrysts and melt inclusions. J. Geophys. Res. 103(18), 277-18, 294.
Civetta, L., D’Antonio, M., de Lorenzo, S., Di Renzo, V., Gasparini, P., 2004. Thermal and geochemical
constraints on the ‘deep’ magmatic structure of Mt. Vesuvius. J. Volcanol. Geotherm. Res. 133, 1–12.
Civetta, L., Galati, R., Santacroce, R., 1991. Magma mixing and convective compositional layering within the
Vesuvius magma chamber. Bull. Volcanol. 53, 287–300.
Civetta, L., Santacroce, R., 1992. Steady state magma supply in the last 3400 years of Vesuvius activity. Acta
Vulcanol. 2, 147–159.
Corrado, G., Rapolla, A., 1981. The gravity field of Italy: analysis of its spectral composition and delineation of
a three-dimensional crustal model for central-southern Italy. Boll. Geof. Teor. Appl. 89, 17–29.
Cortini, M., Ayuso, R.A., De Vivo, B., Holden, P., Somma, R., 2004. Isotopic composition of Pb and Th in
interplinian volcanics from Somma–Vesuvius volcano, Italy. Mineral. Petrol. 80(1–2), 83–96.
Cortini, M., Hermes, O.D., 1981. Sr isotopic evidence for a multi source origin of the potassic magmas in the
Neapolitan area (South Italy). Contrib. Mineral. Petrol. 77, 47–55.
D’Antonio, M., Civetta, L., Orsi, G., Pappalardo, L., Piochi, M., Carandente, A., de Vita, S., Di Vito, M., Isaia,
R., 1999. The present state of the magmatic system of the Campi Flegrei caldera based on a reconstruction
of its behavior in the past 12 ka. J. Volcanol. Geotherm. Res. 91, 247–268.
D’Argenio, B., Pescatore, T., Scandone, P., 1973. Schema Geologico dell’Appennino Meridionale (Campania e
Lucania). Proceedings of Moderne vedute della geologia dell’Appennino. Accademia Nazionale dei Lincei,
183, Roma, Italy.
De Astis, G., Pappalardo, L., Piochi, M., 2004. Procida Volcanic History: new insights in the evolution of the
Phlegraean Volcanic District (Campania region, Italy). Bull. Volcanol. DOI 10.1007/s00445-004-0345-y, 66,
622–641.
Else_DV-DEVIVO_ch009.qxd
202
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
20
1
2
3
4
5
6
7
8
9
30
1
2
3
4
5
6
7
8
9
40
41
42
43
44
45
46
3/2/2006
2:53 PM
Page 202
M. Piochi, B. De Vivo, R.A. Ayuso
Del Moro, A., Fulignati, P., Marianelli, P., Sbrana, A., 2001. Magma contamination by direct wall rock
interaction: constraints from xenoliths from the walls of a carbonate-hosted magma chamber (Vesuvius 1944
eruption). J. Volcanol. Geotherm. Res. 112, 15–24.
De Natale, G., Troise, C., Pingue F., De Gori, P., Chiarabba, C., 2001. Structure and dynamics of the SommaVesuvius volcanic complex. Mineral. Petrol. 73(1–3), 5–22.
De Vivo, B., Ayuso, R.A., Belkin, H.E., Fedele, L., Lima, A., Rolandi, G., Somma, R., Webster, J.D., 2003.
Chemistry, fluid/melt inclusions and isotopic data of lavas, tephra and nodules from ⬎25 ka to 1944 AD of
the Mt. Somma-Vesuvius volcanic activity. Mt. Somma-Vesuvius Geochemical Archive. Dipartimento di
Geofisica e Vulcanologia, Università di Napoli Federico II, Open File Report 1-2003, 143 pp.
Di Maio, R., Mauriello, P., Patella, D., Petrillo, Z., Piscitelli, S., Siniscalchi, A., 1998. Electric and
electromagnetic outline of the Mount Somma-Vesuvius structural setting. J. Volcanol. Geotherm. Res.
82(1–4), 219–238.
Federico, C., Aiuppa, A., Allard, P., Bellomo, S., Jean-Baptiste, P., Parello, F., Valenza, M., 2002. Magma-derived
gas influx and water-rock interactions in the volcanic aquifer of Mt. Vesuvius, Italy. Geochim. Cosmochim.
Acta 66, 963–981.
Fedi, M., Florio, G., Rapolla, A., 1998. 2.5D modelling of Somma-Vesuvius structure by aeromagnetic data.
J. Volcanol. Geotherm. Res. 82(1–4), 239–247.
Ferrucci, F., Gaudiosi, G., Pino, N.A., Luongo, G., 1989. Seismic detection of a major Moho upheaval beneath
the Campania volcanic area (Napoli, southern Italy). Geophys. Res. Lett. 16(11), 1317–1320.
Frondini, F., Chiodini, G., Caliro, S., Cardellini, S., Granieri, D., 2004. Diffuse CO2 soil degassing at Vesuvio,
Italy. Bull. Volcanol. 66(7), 642–651.
Fulignati, P., Gioncada, A., Sbrana, A., 1995. The magma chamber related hydrothermal system of Vesuvius, first
mineralogical and fluid inclusion data on hydrothermalized subvolcanic and lavic samples from
phreatomagmatic eruptions. Per. Mineral. 64, 185–187.
Fulignati, P., Marianelli, P., Métrich, N., Santacroce, R., Sbrana, A., 2004. Towards a reconstruction of the
magmatic feeding system of the 1944 eruption of Mt Vesuvius. J. Volcanol. Geotherm. Res. 133, 13–22.
Fulignati, P., Marianelli, P., Sbrana, A., 1998. New insights on the thermometamorphic-metasomatic magma
chamber shell of the 1944 eruption of Vesuvius. Acta Vulcanol. 10(1), 47–54.
Fulignati, P., Panichi, C., Sbrana, A., Caliro, S., Gioncada, A., Del Moro, A., 2005. Skarn formation at the walls
of the 79 AD magma chamber of Vesuvius (Italy): mineralogical and isotopic constraints. N. Jb. Miner. Abh.
181/1, in press.
Gasperini, D., Blichert-Toft, J., Bosch, D., Del Moro, A., Macera, P., Albarede, F., 2002. Upwelling of deep mantle material through a plate window: evidence from the geochemistry of Italian basaltic volcanoes.
J. Geophys. Res., 107, 2367–2376.
Gilg, H.A., Lima, A., Somma, R., Ayuso, R.A., Belkin, H.E., De Vivo, B., 1999. A fluid inclusion and isotope
study of calc-silicate ejecta from Mt Somma-Vesuvius: evidence for interaction of high-temperature hypersaline fluids with the sedimentary basement. Proceedings of ECROFI XV, Potsdam, Germany. Terra Nostra
99(6), 118–120.
Gilg, H.A., Lima, A., Somma, R., Belkin, H.E., De Vivo, B., Ayuso, R.A., 2001. Isotope geochemistry and fluid
inclusion study of skarns from Vesuvius. Mineral. Petrol. 73, 145–176.
Graham, D.W., Allard, P., Kilburn, C.R.J., Spera, F.J., Lupton, J.E., 1993. Helium isotopes in some historical
lavas from Mount Vesuvius. J. Volcanol. Geotherm. Res. 58, 359–366.
Gupta, A.K., Fyfe, W.S., 2003. The Young Potassic Rocks. Uni. Book, New Daly, 370 pp.
Hermes, O.D. Cornel, W.C., 1981. Quenched crystal mush and associated magma compositions as indicated by
intercumulus glasses from Mt. Vesuvius, Italy. J. Volcanol. Geotherm. Res. 9, 133–149.
Hofman, A.W., Jochum, K.P., Seufert, M., White, W.M., 1986. Nb and Pb in oceanic basalts: new constraints on
mantle evolution. Earth Planet. Sci. Lett. 79, 33–45.
Iannace, A., 1991. Ambienti deposizionali e processi diagenetici in successione di piattaforma carbonatica del
Trias Superiore nei Monti Lattari e Picentini (Salerno). Ph.D. thesis, Università “Federico II”, Napoli, Italy,
221 pp.
Ippolito, F., D’Argenio, B., Pescatore, T., Scandone, P., 1975. Structural-stratigraphic units and tectonic framework of Southern Appennines. In: Squyres, C. (Ed.), Geology of Italy. Lybian Society of Earth Science,
Libyan, Arab Republic, 11 pp.
Joron, J.L., Metrich, N., Rosi, M., Santocroce, R., Sbrana, A., 1987. Chemistry and petrography. In: Santacorce,
R. (Ed.), Somma-Vesuvius. CNR Quad. Ric. Sci. 114, 105–174.
AQ2
Else_DV-DEVIVO_ch009.qxd
3/2/2006
2:53 PM
Page 203
The magma feeding system of Somma-Vesuvius (Italy) strato-volcano
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
20
1
2
3
4
5
6
7
8
9
30
1
2
3
4
5
6
7
8
9
40
41
42
43
44
45
46
203
Landi, A., Bertagnini, A., Rosi, M., 1999. Chemical zoning and crystallization mechanisms in the magma
chamber of the Pomici di Base plinian eruption of Somma-Vesuvius (Italy). Contrib. Mineral. Petrol. 135,
179–197.
Le Bas, M.J., Le Maitre, R.W., Streckeisen, A., Zanettin, B., 1986. A chemical classification of volcanic rocks
based on the total alkali-silica diagram. J. Petrol. 27, 745–750.
Lima, A., Danyushevsky, L.V., De Vivo, B., Fedele, L., 2003. A model for the evolution of the Mt. SommaVesuvius magmatic system based on fluid and melt inclusion investigations. In: De Vivo, B., Bodnar, R.J.
(Eds), Melt Inclusions in Volcanic Systems: Methods, Applications and Problems.Series: Development in
Volcanology. Elsevier, Amsterdam, 272 pp.
Marianelli, P., Métrich, N., Sbrana, A., 1995. Shallow and deep reservoirs involved in magma supply of the 1944
eruption of Vesuvius. Bull. Volcanol. 61(1–2), 48–63.
Marianelli, P., Métrich, N., Sbrana, A., 1999. Shallow and deep reservoirs involved in magma supply of the 1944
eruption of Vesuvius. Bull. Volcanol. 61, 48–63.
Mastrolorenzo, G., Munno, R., Rolandi, G., 1993. Vesuvius 1906: a case study of a paroxysmal eruption and its
relation to eruption cycles. J. Volcanol. Geotherm. Res. 58, 217–237.
Paone, A., 2005. Evidence of crustal contamination, sediment, and fluid components in the campanian volcanic
rocks. J. Volcanol. Geotherm. Res. 138, 1–26.
Pappalardo, L., Civetta, L., D’Antonio, M., Deino, A.L., Di Vito, M.A., Orsi, G., Carandente, A., de Vita, S.,
Isaia, R., Piochi, M., 1999. Chemical and isotopical evolution of the Phlegraean magmatic system before the
Campanian Ignimbrite (37 ka) and the Neapolitan Yellow Tuff (12 ka) eruptions. J. Volcanol. Geotherm. Res.
91, 141–166.
Pappalardo, L., Piochi, M., D’Antonio, M., Civetta, L., Petrini, R., 2002. Evidence for multi-stage magmatic
evolution during the past 60 ka at Campi Flegrei (Italy) deduced from Sr, Nd and Pb isotope data. J. Petrol.
43(7), 1415–1434.
Pappalardo, L., Piochi, M., Mastrolorenzo, G., 2004. The 3800 yr BP–1944 AD magma plumbing system of
Somma-Vesuvius: constraints on its behaviour and present satte through a review of isotope data. Ann.
Geophys. 47(4), 1363–1375.
Pearce, J.A., Norry, M.J., 1979. Petrogenetic implications of Ti, Zr, Y, and Nb variations in volcanic rocks.
Contrib. Mineral. Petrol. 69, 33–47.
Peccerillo, A., 2001. Geochemical similarities between the Vesuvius, Phlegraean Fields and Stromboli Volcanoes:
petrogenetic, geodynamic and volcanological implications. Mineral. Petrol. 73, 93–105.
Peccerillo, A., 2003. Plio-Quaternary magmatism in Italy. Episodes 26, 222–226.
Peccerillo, A., Manetti, P., 1985. The potassic alkaline volcanism of central southern Italy: a review of the data
relevant to petrogenesis and geodinamic significance. Trans. Geol. Soc. South Africa 88, 379–394.
Piochi, M., Ayuso, R.A., De Vivo, B., Somma, R., 2005. Crustal contamination and crystal entrapment during
polybaric magma evolution at the Mt. Somma-Vesuvius volcano, Italy: geochemical and Sr isotope evidence.
Lithos, in revision.
Piochi, M., Civetta, L., Orsi, G., 1999. Mingling in the magmatic system of Ischia (Italy) in the past 5 Ka.
Mineral. Petrol. 66(4), 227–258.
Principe, C., Tanguy, J.C., Arrighi, S., Paiotti, A., Le Goff, M., Zoppi, U., 2004. Chronology of Vesuvius’ activity from AD 79 to 1631 based on archeomagnetism of lavas and hisotrical sources. Bull. Volcanol. 66,
703–724.
Raia, F., Webster, J.D., De Vivo, B., 2000. Pre-eruptive volatile contents of Vesuvius magmas: constrains on
eruptive history and behavior. I – the medieval and modern interplinian activities. Eur. J. Mineral. 12,
179–193.
Rittmann, A., 1933. Die geologisch bedingte Evolution und Differentiation des Somma-Vesuvs-magmas. Zs.
Vulkanologie 15(1–2), 8–94.
Rolandi, G., Maraffi, S., Petrosino, P., Lirer, L., 1993. The Ottaviano eruption of Somma-Vesuvius (8000 y BP):
a magmatic alternating fall and flow-forming eruption. J. Volcanol. Geotherm. Res. 58, 43–65.
Rolandi, G., Petrosino, P., Mc Geehin, J., 1998. The interplinian activity at Somma-Vesuvius in the last 3500
years. J. Volcanol. Geotherm. Res. 82, 19–52.
Rosi, M., Santacroce, R., 1983. The AD 472 “Pollena” eruption: volcanological and petrological data for this
poorly-known, plinian-type event at Vesuvius. J. Volcanol. Geotherm. Res. 17, 249–271.
Rosi, M., Santacroce, S., Sheridan, M.F., 1987. Volcanic hazard. In: Santacroce, R. (Ed.), Somma-Vesuvius.
Quaderni de “La Ricerca Scientifica”, CNR, Italy, 251 pp.
AQ3
Else_DV-DEVIVO_ch009.qxd
204
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
20
1
2
3
4
5
6
7
8
9
30
1
2
3
4
5
6
7
8
9
40
41
42
43
44
45
46
3/2/2006
2:53 PM
Page 204
M. Piochi, B. De Vivo, R.A. Ayuso
Rudnick, R.L., Fountain, D.M., 1995. Nature and composition of the continental crust: a lower crustal
perspective. Rev. Geophys. 33, 267–309.
Santacroce, R.A., Bertagnini, A., Civetta, L., Landi, P., Sbrana, A., 1993. Eruptive dynamics and petrogenetic
processes in a very shallow magma reservoir: the 1906 eruption of Vesuvius. J. Petrol. 34, 383–425.
Savelli, C., 1967. The problem of rock assimilation by Somma-Vesuvius magmas, I. Compositions of SommaVesuvius lavas. Contrib. Mineral. Petrol. 16, 328–353.
Savelli, C., 1968. The problem of rock assimilation by Somma-Vesuvius magmas, II. Compositions of
sedimentary rocks and carbonate ejecta from Vesuvius area. Contrib. Mineral. Petrol. 18, 43–64.
Scandone, R., Iannone, F., Mastrolorenzo, G., 1986. Stima dei parametri dinamici dell’eruzione del 1944 del
Vesuvio. Boll. GNV 2, 487–512.
Somma, R., Ayuso, R.A., De Vivo, B., Rolandi, G., 2001. Major, trace element and isotope geochemistry (Sr-Nd-Pb)
of interplinian magmas from Mt. Somma-Vesuvius (Southern Italy). Mineral. Petrol. 73, 121–143.
Taylor, S.R., Mclennan, S.M. (Eds), 1985. The Continental Crust: Its Composition and Evolution. Blackwell,
Cambridge, 312 pp.
Trigila, R., De Benedetti, A., 1993. Petrogenesis of Vesuvius historical lavas constrained by Pearce element ratios
analysis and experimental phase equilibria. J. Volcanol. Geotherm. Res. 58, 315–343.
Turi, B., Taylor, H.P., 1976. Oxygen isotope studies of potassic volcanic rocks of the Roman Province, Central
Italy. Contrib. Mineral. Petrol. 55, 1–31.
Vilardo, G., Ventura, G., Girolamo, M., 1999. Factors controlling the seismicity of the Somma-Vesuvius volcanic
complex. Volc. Seis. 20, 219–238.
Villemant, B., Trigila, R., De Vivo, B., 1993. Geochemistry of Vesuvius volcanics during 1631–1944 period.
J. Volcanol. Geotherm. Res. 58, 291–313.
Vollmer, R., 1976. Rb–Sr and U–Th–Pb systematics of the alkaline rocks from Italy., Geochim. Cosmochim. Acta
40, 283–295.
Webster, J.D., De Vivo, B., Tappen, C., 2003. Volatiles, magmatic degassing and eruptions of Mt. SommaVesuvius: constraints from silicate melt inclusions, solubility experiments and modeling. In: De Vivo, B.,
Bodnar, R.J. (Eds), Melt Inclusions in Volcanic Systems. Methods, Applications and Problems. Series:
Developments in Volcanology, Vol. 5, Elsevier, Amsterdam, pp. 207–226.
Webster, J.D., Raia, F., De Vivo, B., Rolandi, G., 2001. The behaviour of chlorine and sulfur during differentiation of the Mt. Somma-Vesuvius magmatic system. Mineral. Petrol. 73, 177–200.
Webster, J.D., Sintoni, M.F., De Vivo, B., 2005. The role of sulphur in promoting magmatic degassing and
volcanic eruption at Mt. Somma-Vesuvius. In: De Vivo, B. (Ed.), Vesuvius and Ignimbrites of Campania
Plain. Series Developments in Volcanology. Elsevier, Amsterdam.
Wilson, M. (Ed.), 1989. Igneous Petrogenesis. Unwin Hyman, London, 466 pp.
Zollo, A., Gasparini, P., Virieux, J., Le Meur, H., De Natale, G., Biella, G., Boschi, E., Capuano, P., De Franco,
R., Dell’Aversana, P., De Matteis, R., Guerra, I., Iannaccone, G., Mirabile, L., Vilardo, G., 1996. Seismic
evidence for a low-velocity zone in the upper crust beneath Mount Vesuvius. Science 274, 592–594.

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