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ORIGINAL PAPER
Shoshonite and sub-alkaline magmas from an ultrapotassicvolcano: Sr–Nd–Pb isotope data on the Roccamonfina volcanicrocks, Roman Magmatic Province, Southern Italy
Sandro Conticelli Æ Sara Marchionni Æ Davide Rosa ÆGuido Giordano Æ Elena Boari Æ Riccardo Avanzinelli
Received: 7 February 2008 / Accepted: 3 June 2008 / Published online: 27 June 2008
� Springer-Verlag 2008
Abstract The Roccamonfina volcano is characterised by
two stages of volcanic activity that are separated by vol-
cano-tectonic caldera collapses. Ultrapotassic leucite-
bearing rocks are confined to the pre-caldera stage and
display geochemical characteristics similar to those of
other volcanoes in the Roman Province. After the major
sector collapse of the volcano, occurred at ca. 400 ka,
shoshonitic rocks erupted from cinder cones and domes
both within the caldera and on the external flanks of the
pre-caldera Roccamonfina volcano. On the basis of new
trace element and Sr–Nd–Pb isotope data, we show that
the Roccamonfina shoshonitic rocks are distinct from
shoshonites of the Northern Roman Province, but are very
similar to those of the Neapolitan volcanoes. The last
phases of volcanic activity erupted sub-alkaline magmas as
enclaves in trachytic domes, and as lavas within the Monte
Santa Croce dome. Ultrapotassic rocks of the pre-caldera
composite volcano are plagioclase-bearing leucitites char-
acterised by high levels of incompatible trace elements
with an orogenic signature having troughs at Ba, Ta, Nb,
and Ti, and peaks at Cs, K, Th, U, and Pb. Initial values of87Sr/86Sr range from 0.70926 to 0.70999, 143Nd/144Nd
ranges from 0.51213 to 0.51217, while the lead isotope
rations vary between 18.788–18.851 for 206Pb/204Pb,
15.685–15.701 for 207Pb/204Pb, and 39.048–39.076 for208Pb/204Pb. Shoshonites show a similar pattern of trace
element depletions and enrichments to the earlier ultra-
potassic leucite-bearing rocks but have a larger degree of
differentiation and lower concentrations of incompatible
trace elements. On the other hand, shoshonitic rocks have
Sr, Nd, and Pb isotopes consistently different than pre-
caldera ultrapotassic leucite-bearing rocks. 87Sr/86Sr ranges
from 0.70665 to 0.70745, 143Nd/144Nd ranges from
0.51234 to 0.51238, 206Pb/204Pb ranges from 18.924 to
19.153, 207Pb/204Pb ranges from 15.661 to 15.694, and208Pb/204Pb ranges from 39.084 to 39.212. High-K calc-
alkaline samples have intermediate isotopic values between
ultrapotassic plagioclase leucitites and shoshonites, but the
lowest levels of incompatible trace element contents. It is
argued that ultrapotassic magmas were generated in a
modified lithospheric mantle after crustal-derived meta-
somatism. Interaction between the metasomatic agent and
lithospheric upper mantle produced a low-melting point
metasomatised veined network. The partial melting of the
veins alone produced pre-caldera leucite-bearing ultra-
potassic magmas. It was possibly triggered by either post-
collisional isotherms relaxation or increasing T�C due
Communicated by T.L. Grove.
Electronic supplementary material The online version of thisarticle (doi:10.1007/s00410-008-0319-8) contains supplementarymaterial, which is available to authorized users.
S. Conticelli � S. Marchionni � D. Rosa � E. Boari �R. Avanzinelli
Dipartimento di Scienze della Terra, Universita degli Studi di
Firenze, Via Giorgio La Pira, 4, 50121 Florence, Italy
S. Conticelli (&)
Consiglio Nazionale delle Ricerche, Istituto di Geoscienze
e Georisorse, Sezioni di Firenze, Via Giorgio La Pira,
4, 50121 Florence, Italy
e-mail: [email protected]
G. Giordano
Dipartimento di Scienze Geologiche, Universita di Roma III,
Largo San Leonardo Murialdo, 1, 00100 Rome, Italy
Present Address:
R. Avanzinelli
Bristol Isotope Group, Department of Earth Sciences,
Wills Memorial Building, University of Bristol,
Bistol BS8 1RJ, UK
123
Contrib Mineral Petrol (2009) 157:41–63
DOI 10.1007/s00410-008-0319-8
increasing heat flow through slab tears. Shoshonitic mag-
mas were generated by further melting, at higher
temperature, of the same metasomatic assemblage with
addition 10–20% of OIB-like astenospheric mantle mate-
rial. We suggest that addition of astenospheric upper
mantle material from foreland mantle, flowing through slab
tearing after collision was achieved.
Keywords Sr–Nd–Pb isotopes � Plagioclase leucitite �Shoshonite � Sub-alkaline basaltic andesite �Roccamonfina volcano � Roman Magmatic Province �Orogenic magmas � Slab tearing � Asthenospheric inflow
Introduction
Roccamonfina was the first volcano on the Italian Penin-
sula to be investigated in detail (i.e. Appleton 1972;
Ghiara et al. 1973; Cox et al. 1976; Carter et al. 1978;
Taylor et al. 1979). Detailed petrographic and volcano-
logic studies defined the volcanic succession and the
eruption styles (e.g. Giannetti and Luhr 1983; Luhr and
Giannetti 1987; Cole et al. 1992, 1993; Valentine and
Giannetti 1995; De Rita and Giordano 1996; Giannetti
1996a, b; Giordano 1998a, b), and discussed the nature of
the xenolith assemblage (Giannetti and Luhr 1990). Roc-
camonfina mafic volcanic rocks have been used to address
the issue of the genesis of Italian Potassic and ultra-
potassic magmatism (e.g. Hawkesworth and Vollmer
1979; Vollmer and Hawkesworth 1980; Ellam et al. 1989;
Beccaluva et al. 1991; Conticelli and Peccerillo 1992;
Giannetti and Ellam 1994; D’Antonio et al. 1996; Conti-
celli et al. 2002, 2007; Peccerillo 2005a), however, there
have been no detailed studies of the distribution of major
and trace elements and Sr–Nd–Pb isotopes in the various
phases of the Roccamonfina volcano since the study of
Appleton (1972).
Conticelli et al. (2004) showed that low potassium series
of Appleton (1972) is better defined as a shoshonitic series.
Shoshonitic rocks are leucite-free and are characterised by
lower K contents than ultrapotassic lavas. In Italy, shos-
honitic rocks generally post-date the ultrapotassic
magmatism (i.e. Tuscany, Vulsini, Vico; Conticelli et al.
1991, 2007; Perini et al. 2000, 2003, 2004), except in the
Neapolitan area, where the present activity at Vesuvius is
ultrapotassic.
Geochemical and isotopic variations in the high-MgO
rocks of the Roman Magmatic Province have been
described by several authors (Beccaluva et al. 1991;
D’Antonio et al. 1996; Conticelli et al. 2002; Peccerillo
2005a). Recently Avanzinelli et al. (2008) have shown that
the Neapolitan volcanoes are consistently different in their
U–Th disequilibria with respect to the volcanoes of Latium
(i.e., Vulsini, Vico, Sabatini, Colli Albani). Thus, Rocca-
monfina together with the Middle Latin Valley district
(Boari and Conticelli 2007; Frezzotti et al. 2007; Boari
et al. 2008a, in press), represents a key area for the
understanding the nature of the geochemical and isotopic
transition from the Latian to the Neapolitan sector of the
Roman Magmatic Province (Conticelli et al. 2004, 2007;
Peccerillo 2005a). In the present study, major and trace
element concentrations, together with Sr, Nd, and Pb iso-
tope ratios have been determined for Roccamonfina
volcanic rocks with the aim of elucidating the genetic
relationships between ultrapotassic leucite-bearing rocks
and shoshonitic lavas.
Geological and volcanological background
The Roccamonfina volcano is part of the Auruncan District
of Washington (1906). The volcano lies at the intersection
of important NE–SW, NW–SE and N–S tectonic linea-
ments cut the Mesozoic–Cenozoic Apennine carbonatic
sequences (Accordi 1963; Incoronato et al. 1985; Accordi
and Carbone 1988; Mattei et al. 1993; Giordano et al.
1995). The Roccamonfina volcanics are located in the NE-
trending Garigliano graben, filled by transgressive marine
sedimentary sequence (Ippolito et al. 1973; Watts 1987;
Giordano et al. 1995).
The Roccamonfina composite volcano is made up by
lavas and pyroclastic rocks erupted in three main periods of
activity, which accompanied the formation of the poly
phased summit caldera (De Rita and Giordano 1996).
Volcanic activity begun at 630 ka (Ballini et al. 1989a)
with a phase dominated by leucite-bearing lava flows inter-
bedded to minor ash fall and mud-flow deposits (Fig. 1).
Peripheral dikes and eccentric monogenetic volcanoes
were also emplaced in the area surrounding the volcano (Di
Girolamo et al. 1991).
The formation of the summit caldera sector collapse
marked the passage to the second period of activity (De
Rita and Giordano 1996).
The second period is characterised by plinian paroxistic
volcanic activity between 385 and 230 ka (Luhr and
Giannetti 1987), with the eruption of five main, caldera
forming pyroclastic flow units (Giannetti and Luhr 1983;
Luhr and Giannetti 1987; Ballini et al. 1989b; Cole et al.
1993; Bosi and Giordano 1997; Giordano 1998a, b) that are
the Brown Leucitic Tuff and the succession of the White
Trachytic Tuffs (De Rita et al. 1998).
The third and last period of post-caldera activity spans
between 155 and 50 ka (Cortini et al. 1973; Fornaseri
1985; Radicati di Brozolo et al. 1988). Leucite-free lavas
have been poured out in the form of intra- and peri-caldera
exogenous trachytic domes but small leucite-free mafic
42 Contrib Mineral Petrol (2009) 157:41–63
123
lava flows are also found within the caldera (Cole et al.
1992), and in some final monogenetic parasitic vents on the
flank of the volcano (Fig. 1).
For the purposes of this paper, the first period of activity
at Roccamonfina (630–400 ka) is named hereafter ‘‘pre-
caldera period’’, whereas the following two periods, the
paroxysm (385–230 ka) and the final one (155–50 ka), are
collectively named ‘‘post-caldera period’’.
Samples and analytical techniques
Forty-nine fresh samples representative of the two stages of
activity at the Roccamonfina volcano have been selected
for the present study. Their petrography, together with
sample localities, is reported in Table 1.
Major and trace elements on whole rocks were deter-
mined at the DST of Firenze University using XRF and wet
Volcanic districts (composite volcanoes)
Monogenetic volcano, dykes, hypabissal body
LuMP
RMP
TMP
Lucanian Magmatic Province
Roman Magmatic Province
Tuscan Magmatic Province
Limit of the Apennine front
Position and depth of present-day benioff zone
Cenozoic to present time Withinplate rocksexternal to Apennine-Tyrrhenian system
Aeolian Arc - calc-alkalic volcanoes
LEGEND:
Pietre Nere (70 Ma)
Vulture
Etna
Iblei
Aeolian Arc
Middle Latin Valley
Phlegrean
Roccamonfina
VesuviusIschiaPontine Is.
TMP
Pantelleria
Ustica
LuMP
Euganei (50 Ma)
Linosa
38° 38°
40° 40°
42° 42°
44° 44°
08° 10° 12° 14° 16° 18°
18°
20°
10° 12° 14° 16°
250
350
450
150
LD-RMP
ND-RMP
Pescosansonesco (70 Ma)
inflow
CMP
Fig. 1 Distribution of volcanism in Italy and geological sketch map
of Roccamonfina (redrawn after: Taylor et al. 1979; Cole et al. 1992;
Conticelli et al. 2007). Inset shows the location of the Roccamonfina
Volcano with respect to the rest of the Roman Province and the
definition of the Latian Districts of the Roman Magmatic Province
(RMP-LD) and the Neapolitan District of the Roman Magmatic
Province (RMP-ND). Note that the CMP represent the Corsica
Magmatic Province as defined by Conticelli et al. (2008, in press).
1 Campanian Ignimbrite (erupted from Campi Flegrei caldera at 39 ka),
late phase of post-caldera activity (Vezzara synthem; 155–50 ka),
2 HKCA final lavas, 3 Shoshonitic mafic lava and pyroclastics from
monogenetic centres, 4 Shoshonitic domes, 5 Yellow Trachytic Tuff,
early phase of post-caldera activity (Riardo synthem; 385–230 ka),
6 White Trachytic Tuffs, 7 Teano pyroclastic succession, 8 Brown
Leucitic Tuff, 9 pre-caldera activity Leucite-bearing lava and
pyroclastics (plagioclase leucitites) (Roccamonfina synthem; 630–
385 ka), 10 Mesozoic–Cenozoic pre-orogenic carbonatic-terrigenous
succession; 11 main extensional faults, 12 caldera rim, 13 scoria
cones
Contrib Mineral Petrol (2009) 157:41–63 43
123
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44 Contrib Mineral Petrol (2009) 157:41–63
123
Ta
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c,g
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of
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at
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t
Po
rph
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tic,
vis
icu
lar,
gla
ssy
gd
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lv+
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x+
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x
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lv+
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ss
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N3
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ian
nem
aie
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13
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orp
hy
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yst
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d](
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dd
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orp
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(Ch
r)+
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orp
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el](
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r)+
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7C
ian
nem
aie
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100 N
13
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900 E
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CA
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alla
va
Su
b-p
orp
hy
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c,p
ylo
tax
itic
gd
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lv(C
hr)
+P
lg+
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x+
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+C
px
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lv+
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ss
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N3
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og
gio
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lara
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13
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CA
Fin
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va
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b-p
orp
hy
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c,g
lass
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(Ch
r)+
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lg+
Olv
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px
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lass
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N3
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gio
Mo
lara
41
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200 N
13
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800 E
HK
CA
Fin
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va
Su
b-a
ph
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c,cr
yp
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yst
alli
ne
gd
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lv(C
hr)
+P
lg+
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x+
Gla
ss
Contrib Mineral Petrol (2009) 157:41–63 45
123
chemical methods. MgO and Na2O were determined by
AAS, FeO by titration (after Shapiro and Brannock 1962),
and LOI gravimetrically. XRF data were corrected for
matrix effects following the methods of Franzini et al.
(1972) for major elements, and that of de Vries and Jenkins
(1971) for trace elements. REE, Ta, Hf, Th, Co, and Sc
were analysed by INAA (DST, Firenze University) fol-
lowing the procedure described by Poli et al. (1977) and by
ICP-MS (ACTLAB). Errors for trace elements are better
that 10% for Co, Sc, Nd, Lu, Tb, and Th, and better than
5% for the other elements. Bias between INAA and ICP-
MS was evaluated using international reference samples as
unknown, and was found to be within the range of ana-
lytical error.
Sr, Nd, and Pb isotopes were analysed at the DST of the
Firenze University following the procedures outlined by
Avanzinelli et al. (2005). Digested rocks solutions were
used for Sr and Nd purification through standard liquid
chromatographic techniques. Sr and Nd isotopic ratios
were measured by thermal ionisation mass spectrometry
(TIMS) using a Thermofinnigan Triton TI in a triple
jumping multi-dynamic mode (Thirlwall 1991; see also
Avanzinelli et al. 2005 for further details). Mass fraction-
ation of Sr and Nd isotopes has been exponentially
corrected with 86Sr/88Sr = 0.1194 and 146Nd/144Nd =
0.7219, respectively. 87Sr/86Srtriple average value for NBS
987 reference sample was 0.710251 ± 12 (2r, n = 70):143Nd/144Ndtriple average value for La Jolla reference sam-
ples was 0.511845 ± 7 (2r, n = 25). Pb was purified
following the method described by Deniel and Pin (2001)
using 100–150 lm Sr-spec resins in quartz fibres micro-
columns. The Pb separation efficiency was evaluated to be
about 97%. Pb samples were loaded onto zone-refined Re
filaments, with addition of 0.5 ll of silica gel and 1 ll of
high-purity H3PO4 and measured in static mode with a
Thermofinnigan Triton TI�; average runs were measured at
1,400�C and yielded *1.5 V of 208Pb. Mass bias was
monitored with repeated measurements of SRM 981 refer-
ence standard and we obtained a mass discrimination
factor (e) of 0.15% per a.m.u. The external reproducibility
of the international reference standard SRM 981 was:208Pb/204Pb = 36.495 ± 23; 207Pb/204Pb = 15.423 ± 7;206Pb/204Pb = 16.888 ± 6; 207Pb/206Pb = 0.91328 ± 15;208Pb/207Pb = 2.3662 ± 4; 208Pb/206Pb = 2.1610 ± 7
(2r, n = 45).
Petrography and geochemistry
Pre- and post-caldera volcanic rocks from Roccamonfina
are distinct in terms of their mineralogy and petrography
(Table 1). Pre-caldera rocks are leucite-bearing with
clinopyroxene and plagioclase ubiquitously present asTa
ble
1co
nti
nu
ed
Sam
ple
Lo
cali
tyL
atit
ud
eL
on
git
ud
eS
erie
sR
ock
typ
e
Tex
ture
Pet
rog
rap
hy
RM
N3
5P
og
gio
Mo
lara
41
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200 N
13
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800 E
HK
CA
Fin
alla
va
Su
b-p
orp
hy
riti
c,p
ylo
tax
itic
gd
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px
+O
lv(C
hr)
+P
lg+
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+O
lv+
Cp
x
RM
N3
6S
elle
tta
41
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100 N
13
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CA
Fin
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orp
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c,m
ycr
ocr
yst
.g
dm
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+C
px
+O
lv+
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+C
px
+O
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Op
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N0
2C
ian
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aie
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ph
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tic,
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pto
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st.
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+O
p
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N1
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gio
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lara
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CA
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orp
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c,g
lass
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dm
Plg
+C
px
+O
lv+
Plg
+C
px
+O
p
+G
lass
En
trie
sw
ith
inb
rack
ets
are
min
eral
sen
clo
sed
inth
ep
rece
edin
gm
iner
al;
wit
hin
squ
ared
bra
cket
sar
ete
xtu
ral
feat
ure
of
the
min
eral
:re
sre
sorb
ed,
idd
idd
ing
site
d;
inb
old
are
the
ph
eno
cry
sts;
in
ital
ics
and
un
der
lin
edar
eth
ex
eno
cry
sts
HK
Sp
lag
iocl
ase
leu
citi
te,
SH
Osh
osh
on
ite,
HK
CA
hig
h-K
calc
-alk
alin
e,O
lvo
liv
ine,
Ch
rch
rom
ite,
Cp
xcl
ino
py
rox
ene,
Leu
leu
cite
,B
iob
ioti
te,
Plg
pla
gio
clas
e,O
po
paq
ue,
Ap
aap
atit
e,
Gl
gla
ss,
Ga
gar
net
,S
dsa
nid
ine,
Sp
hsp
hen
e
46 Contrib Mineral Petrol (2009) 157:41–63
123
phenocrysts, and olivine only in the most mafic members.
Apatite and opaque phases are ubiquitous in the ground-
mass. Resorbed biotite and titanite also occur in the most
felsic samples. These rocks are ultrapotassic and range in
composition from basanite to phonolite (Fig. 2). Foley
(1992a) referred to Italian leucite-bearing rocks as plagio-
clase leucitites to distinguish them from within-plate
leucitites in which Al2O3 is extremely low (e.g. Rogers
et al. 1992, 1998).
Post-caldera rocks are leucite-free, with ubiquitous
clinopyroxene phenocrysts. Different phenocrysts are
present with clinopyroxene depending on the degree of
differentiation: olivine in the most mafic samples, plagio-
clase and biotite in the intermediate to felsic products and
sanidine, often as a megacryst, is restricted to the most
felsic samples along with rare titanite. On the basis of
chemical characteristics and temporal succession, the post-
caldera lavas can be further divided into two groups. The
early post-caldera lavas (400–155 ka) are shoshonitic in
composition and range from basalt to trachyte (Fig. 2a).
The final lavas (155–50 ka) have the lowest total alkali and
K2O contents, at comparable silica, of the entire Rocca-
monfina sequence (Fig. 2). They are sub-alkaline basaltic
andesites (Fig. 2a), that straddle the boundary between the
shoshonite series and High-K calc-alkaline series (Fig. 2b).
Pre- and post-caldera rocks show distinct trends in major
and trace element variation diagrams with MgO (Fig. 3).
Pre-caldera plagioclase leucitites show the highest levels of
K2O, FeO, TiO2, Rb and most of the incompatible elements
contents, and they increase with decreasing MgO contents
(Fig. 3).
Among post-caldera rocks, the final sub-alkaline lavas
(HKCA) have fairly homogeneous MgO contents
(Table 2), whereas early post-caldera rocks (i.e. shosho-
nites) are enriched in SiO2, Na2O, and Nb at comparable
MgO contents (Table 2; Fig. 3).
Small differences are shown on spider diagrams nor-
malised to primordial mantle between pre- and post-caldera
rocks (Fig. 4). Plagioclase leucitites have large peaks at Cs
and Pb, and small one at U and Sr; large through are
present at Ba, Ta, Nb, and Ti, with minor through at Nd, P,
and Hf (Fig. 4). Normalised Ta/Nb is \1. Early post-cal-
dera leucite-free rocks (i.e., shoshonites) have large peaks
at Cs and Pb, but still smaller than those shown by pla-
gioclase leucitites (Fig. 4). Thought at Ta, Nb, and Ti are
shown, with minor ones at Ba, Nd, and P. Normalised Ta/
Nb is variable from \1 to [1. The final post-caldera lavas
(i.e., HKCA), show the smallest peak and through magni-
tudes. Significant differences are shown by disappearance
of Ba through and inversion of the normalised Ta/Nb
values which are [1 (Fig. 4).
A twofold behaviour is also shown by isotopic compo-
sitions (Table 3). Plagioclase leucitites (i.e. pre-caldera)
have the highest initial 87Sr/86Sr (0.70926–0.70999) and
the lowest initial 143Nd/144Nd values (0.51213–0.51217),
respectively (Fig. 5). Little or no variation of initial87Sr/86Sr with decreasing MgO are shown by within either
plagioclase-leucitites of pre-caldera phase or leucite-free
post-caldera rocks (0.70665–0.70745), with final sub-
alkaline lavas intermediate (0.70748–0.70749) between
pre- and post-caldera rocks (Fig. 5). On the whole 87Sr/86Sr
and 143Nd/144Nd of Roccamonfina rocks show a clear
negative covariation straddling the fields of rocks from the
Latian districts (RMP-LD) and the Neapolitan one (RMP-
ND) of the Roman Magmatic Province (Fig. 6). The same
covariation is observed for 208Pb/204Pb, 87Sr/86Sr, and143Nd/144Nd vs. 206Pb/204Pb diagrams (Fig. 7), with
shoshonites showing the highest 206Pb/204Pb (18.924–
19.153) and 208Pb/204Pb (39.084–39.212) values and pla-
gioclase leucitites the lowest 206Pb/204Pb (18.788–18.851)
and 208Pb/204Pb (39.048–39.076) values (Table 3).
Discussion
The origin of the extremely enriched trace element com-
position of Italian potassic and ultrapotassic volcanoes
their fractionated LILE/HFSE and their isotopic signature
has been thoroughly discussed in many studies about Ita-
lian magmatism (e.g. Conticelli et al. 2004; Peccerillo
2005a, for reviews). To briefly summarise the genetic
scenario, Italian magmas in general, and Roccamonfina in
UltrapotassicSeries(HKS)
Shoshonitic Series(SHO)
High-K Calk-alkalicSeries
Calk-alkalic
Tholeiitic Series
A BFig. 2 Classification diagrams,
K2O + Na2O versus SiO2 (total
alkali silica; Le Bas et al. 1986)
and K2O versus SiO2 (Peccerillo
and Taylor 1976), for
ultrapotassic rocks of
Roccamonfina volcano. Note
that data are plotted on a
volatile-free basis
Contrib Mineral Petrol (2009) 157:41–63 47
123
particular, have been generated in a sub-continental litho-
spheric mantle, enriched by the addition of crustal material,
recycled probably as sedimentary melts via subduction
(Peccerillo 1985, 2005a, b; Conticelli and Peccerillo 1992).
Silica saturation of ultrapotassic has been controlled by
XCO2during partial melting of the metasomatised mantle
source partial melting (Wendlandt and Eggler 1980a, b). In
this scenario, the CO2-rich component might have been
released during partial melting of CaCO3-rich subducted
marly sediment (Conticelli et al. 2004; Avanzinelli et al.
2008). Then de-volatilisation of CaCO3 sedimentary com-
ponent might provide the CO2 to increase the XCO2and to
provide the necessary CaO to re-fertilise the lithospheric
refractory mantle source. High-flux of CO2, with typical
crustal-derived oxygen isotopic values, has been recorded
in the Roman Magmatic Province (e.g. Bertrami et al.
1990; Chiodini and Frondini 2001; Beaubien et al. 2003).
In addition Conticelli et al. (2002, 2007) have shown that
initial 87Sr/86Sr and 143Nd/144Nd for Roman Magmatic
Province anticorrelate pointing to a crustal reservoir with
the isotopic composition intermediate between those of
shales and limestones. Leucite-bearing rocks from Rocca-
monfina volcano fall along this trend, with isotopic values
typical of leucite-bearing rocks (plagio-leucitites, leuci-
tites, and kamafugites) of the Roman Magmatic Province
but slightly less enriched in radiogenic Sr (Fig. 6).
Previous studies, however, have shown that Neapolitan
ultrapotassic volcanoes (RMP-ND) display clear differ-
ences in many geochemical (Beccaluva et al. 1991) and
isotopic (Peccerillo 2005a, and references therein) tracers
respect with ultrapotassic volcanic rocks belonging to the
northern district of the Roman Magmatic Province (RMP-
LD). The process responsible for this variation is still
matter of debated and it might involves several different
factors, such as: (1) the influence of an asthenospheric
component prior to metasomatism (Beccaluva et al. 1991;
Fig. 3 Differentiation diagrams
for some major (wt.%) and trace
(ppm) elements versus MgO
wt.%. Note that leucite-bearing
and leucite-free rocks plots
along different trends
48 Contrib Mineral Petrol (2009) 157:41–63
123
Table 2 Representative chemical analyses of Roccamonfina rocks
Series Pre-caldera: leucite-bearing Post-caldera: leucite-free shoshonites
Sample RMN 44 RMN 18 RMN 46 RMN 45 RMN 43 RMN 11 RMN 14 RMN 09 RMN 16 RMN 04
Number 1 2 3 7 8 12 13 14 15 17
SiO2 46.3 48.2 49.0 50.8 52.6 47.3 47.7 48.2 48.1 51.1
TiO2 0.97 0.89 0.78 0.69 0.58 0.91 0.91 0.82 0.80 0.82
Al2O3 15.3 16.6 19.9 19.9 20.1 15.8 17.0 17.6 17.0 18.6
Fe2O3 4.73 3.99 1.70 3.12 1.32 2.48 3.29 3.57 2.99 3.79
FeO 4.10 4.01 5.70 3.48 3.98 5.96 5.80 5.08 5.96 4.03
MnO 0.15 0.15 0.16 0.17 0.12 0.15 0.16 0.15 0.16 0.14
MgO 6.61 5.78 2.80 1.78 1.75 9.35 8.94 7.10 8.67 5.87
CaO 12.6 10.2 7.64 7.02 5.16 12.1 12.0 11.2 12.4 9.15
Na2O 1.60 1.99 2.67 2.69 2.41 1.32 1.36 1.75 1.68 2.17
K2O 6.63 7.29 8.10 8.65 10.41 1.29 1.86 3.16 1.62 3.41
P2O5 0.62 0.51 0.42 0.37 0.36 0.30 0.27 0.37 0.27 0.31
LOI 0.58 0.76 1.07 0.93 1.01 3.22 0.74 1.14 0.58 0.67
Sum 100.18 100.27 99.90 99.65 99.74 100.11 100.00 100.09 100.11 100.05
Mg–V 62.38 61.46 44.81 37.25 41.54 70.53 68.15 64.23 67.76 62.33
Alk 8.23 9.28 10.77 11.34 12.82 2.61 3.22 4.91 3.30 5.58
Sc nd 29.6 nd nd nd 43.8 31.9 32.7 45.5 26.9
V 312 267 239 228 141 nd nd nd nd nd
Cr 164 154 bdl bdl 3 350 330 313 330 240
Co 34.5 30.6 24.4 14.6 15.4 43 40 39 47 36
Ni 72 54 21 6 11 74 76 56 74 47
Cu 109 nd 40 17 43 nd nd nd nd nd
Zn 83 nd 86 112 85 nd nd nd nd nd
Ga 18 nd 21 21 19 nd nd nd nd nd
Rb 322 345 358 511 606 189 177 191 153 152
Sr 1,784 1,842 1,890 2,190 1,670 819 777 1,152 784 882
Y 38.9 40.0 39.3 39.7 38.4 30 24 30 31 32
Zr 226 255 279 289 256 146 157 157 156 166
Nb 10.5 10.4 10.3 19.5 18.2 16 16 13 16 15
Cs 31.0 36.0 25.1 25.5 46.3 18.0 9.0 9.0 4.0 4.0
Ba 1,460 1,706 1,460 1,450 1,280 841 600 604 594 693
La 105.4 96.3 122.0 134.8 98.3 40.7 44 43.7 27.3 43.6
Ce 210.8 185.0 244.4 258.6 185.1 77 91 87 50 80
Pr 24.9 23.8 24.5 28.3 19.6 nd nd nd nd nd
Nd 90.0 93.0 90.0 97.2 65.5 36 44 42 26 38
Sm 18.4 17.6 16.0 17.4 11.5 7.66 9.29 9.06 6.04 7.70
Eu 3.70 3.50 3.29 3.51 2.31 1.88 2.27 2.03 1.63 1.77
Gd 12.9 12.5 11.1 10.8 7.44 nd nd nd nd nd
Tb 1.81 1.80 1.49 1.59 1.08 0.7 1.0 0.9 0.7 0.8
Dy 7.32 7.05 6.82 6.94 4.82 nd nd nd nd nd
Ho 1.19 1.17 1.18 1.21 0.82 nd nd nd nd nd
Er 2.96 3.14 3.28 3.30 2.33 nd nd nd nd nd
Tm 0.367 0.403 0.448 0.453 0.323 nd nd nd nd nd
Yb 2.16 2.22 2.71 2.80 2.02 1.73 1.88 1.92 1.64 2.33
Lu 0.311 0.320 0.389 0.406 0.292 nd nd nd nd nd
Hf 6.38 5.99 5.83 6.61 4.3 2.8 4.1 3.8 2.8 4.3
Ta 0.54 0.58 0.52 0.91 0.87 0.90 0.35 0.75 0.38 0.81
Contrib Mineral Petrol (2009) 157:41–63 49
123
Table 2 continued
Series Pre-caldera: leucite-bearing Post-caldera: leucite-free shoshonites
Sample RMN 44 RMN 18 RMN 46 RMN 45 RMN 43 RMN 11 RMN 14 RMN 09 RMN 16 RMN 04
Pb 50.6 51.5 61.7 71.6 52.3 8.71 8.11 12.9 5.67 16.9
Th 36.7 43.0 47.9 46.3 40.4 7.8 7.5 7.6 4.3 13.0
U 8.68 9.21 11.5 11.4 9.8 1.7 2.3 2.0 1.0 3.3
Series Post-caldera: leucite-free shoshonites Post-caldera: leucite free HKCA
Sample RMN 17 RMN 48 RMN 24 RMN 01 RMN 30 RMN 42 RMN 22 RMN 29 RMN 39 RMN 33 RMN 12
Number 18 19 25 26 28 29 32 35 38 42 47
SiO2 51.1 51.7 54.4 54.4 55.2 55.2 58.0 52.3 52.3 53.4 53.9
TiO2 0.85 0.73 0.73 0.78 0.73 0.69 0.62 0.83 0.80 0.80 0.80
Al2O3 17.4 18.4 18.3 18.8 19.0 19.2 18.7 19.0 19.2 18.6 18.8
Fe2O3 3.49 2.21 2.09 1.45 4.14 1.89 2.86 2.13 1.90 1.92 2.16
FeO 3.54 4.60 4.37 5.04 2.46 4.10 2.60 6.21 6.17 6.09 5.84
MnO 0.14 0.15 0.14 0.15 0.16 0.14 0.13 0.16 0.15 0.15 0.15
MgO 7.76 5.91 3.14 3.54 3.04 2.96 2.68 4.67 4.63 4.44 4.31
CaO 10.1 8.08 7.25 7.53 6.24 6.51 5.57 8.67 8.25 8.58 8.15
Na2O 2.07 2.22 2.86 2.53 2.89 3.04 2.97 2.08 2.18 2.16 2.10
K2O 2.94 4.10 4.93 5.06 4.45 5.24 4.86 2.86 2.99 3.00 2.98
P2O5 0.25 0.24 0.30 0.24 0.24 0.28 0.20 0.18 0.20 0.18 0.17
LOI 0.55 1.68 1.75 1.58 1.36 0.76 0.83 0.88 1.22 0.63 0.57
Sum 100.19 100.06 100.18 101.10 99.86 100.00 100.00 100.00 100.00 100.00 99.90
Mg–V 70.90 65.29 51.30 53.92 50.76 51.70 52.08 54.65 55.20 54.36 53.73
Alk 5.01 6.32 7.79 7.59 7.34 8.28 7.83 4.94 5.17 5.16 5.08
Sc 35.6 nd nd 13.4 nd nd nd nd nd nd 18.6
V nd 201 205 nd 189 195 159 199 212 202 nd
Cr 300 254 14 25 9 14 20 38 37 43 24
Co 35 24.7 20.3 16.4 19.9 19.1 15.2 26.2 25.2 23.8 24.4
Ni 66 51 10 14 11 9 12 14 16 17 14
Cu nd 59 43 nd 51 36 21 30 26 15 nd
Zn nd 61 68 nd 81 69 64 75 93 99 nd
Ga nd 16 19 nd 20 20 19 19 21 19 nd
Rb 132 146 207 153 162 230 188 120 118 132 152
Sr 806 723 1,060 909 898 1,070 773 857 910 892 944
Y 28 35.4 32.0 32 30.8 33.8 31.8 25.3 28.1 26.2 30
Zr 174 150 205 155 199 228 211 128 136 139 151
Nb 9 11.9 16.2 16 16.6 18.4 19.3 10.2 11.0 10.6 10
Cs 5.0 3.67 10.8 nd 4.98 14.4 7.06 7.14 6.62 7.67 nd
Ba 581 630 752 587 656 792 561 561 626 580 572
La 36.5 70.5 63.0 62 53.2 69.0 64.6 37.0 42.0 39.0 42
Ce 67 100.1 128.6 114 108.9 138.4 120.9 78.0 81.9 78.7 71
Pr nd 13.2 13.4 nd 11.2 14.4 12.0 8.34 9.27 8.72 nd
Nd 31 50.4 52.5 49 42.7 55.2 44.5 32.9 36.5 34.1 38
Sm 6.45 9.89 10.5 8.40 8.65 10.7 8.57 6.91 7.44 6.91 7.60
Eu 1.60 2.23 2.40 1.92 1.97 2.45 1.91 1.63 1.69 1.65 1.58
Gd nd 8.30 8.12 nd 6.85 8.11 6.67 5.59 6.05 5.72 6.0
Tb 0.8 1.27 1.21 1.0 1.07 1.26 1.06 0.86 0.94 0.91 0.8
Dy nd 6.10 5.92 nd 5.44 6.15 5.33 4.44 4.83 4.59 nd
Ho nd 1.13 1.08 nd 1.06 1.14 1.04 0.90 0.97 0.90 nd
50 Contrib Mineral Petrol (2009) 157:41–63
123
Peccerillo and Panza 1999); (2) variation in the composi-
tion of the metasomatic agent; (3) the presence of a further
metasomatic event in the Neapolitan area (Peccerillo
2005a; Avanzinelli et al. 2008). In this context the Roc-
camonfina volcano has many characteristics, in addition to
geographic position, to represent a key point to solve this
issue. Differently from the northermost Roman Volcanoes
(RMN-LD) at Roccamonfina volcano occur shoshonitic to
high-K calc-alkalic rocks following silica undersaturated
plagioclase leucitites. This shoshonitic volcanism is coeval
to the appraisal and building up of the Neapolitan volca-
noes (RMP-ND) (Conticelli et al. 2004, and references
therein). On the basis of the incompatible trace element and
Sr, Nd, and Pb data (Tables 2, 3) it is clear that Rocca-
monfina shoshonites have many geochemical and isotopic
similarities with Neapolitan shoshonites (RMP-ND),
whereas pre-caldera plagioclase leucitites still fall well
within the geochemical and isotopic field of other ultra-
potassic Roman volcanoes (RMP-LD) (Fig. 7). Boari and
Conticelli (2007) have shown that coeval shoshonites also
occur in the Middle Latin Valley monogenic volcanic field,
few km north of Roccamonfina, associated to plagioclase
leucitites, kamafugites and calc-alkalic magmatism. In that
case extensive detailed studies on fresh rocks have shown
that incompatible trace elements and isotopic characteris-
tics of shoshonites and calc-alkalic magmas from Middle
Latin Valley are not different from those of northernmost
Roman magmas (RMP-LD) and therefore significantly
different from those of the Neapolitan volcanoes (RMP-
ND) (Boari et al. 2008a, in press).
Shallow level differentiation processes
Before tackling any source process, it is necessary to
investigate the effect of shallow level processes. The aim
of this section is not to reproduce or model the evolution of
the magmas in the shallow reservoir of Roccamonfina
volcano, but to evaluate the possibility that the different
series were cogenetic and related one to the other by crystal
fractionation, crustal assimilation, or a combination of both
(AFC).
There is no doubt that pre-caldera and post-caldera
volcanic rocks at Roccamonfina volcano follow distinct
differentiation trends (Fig. 3). Post-caldera leucite free
rocks can be further divided into two groups: the early
post-caldera shoshonitic rocks, and the late post-caldera
high-K calc-alkalic rocks. Low pressure differentiation
processes are then required for modelling the composi-
tional variations within each group of rocks recognised.
Small Sr and Nd isotopic variations with MgO decreasing
are shown within each trend (Fig. 5), indicating that dif-
ferentiation at low pressure of each trend is mainly driven
by either fractional crystallisation (FC) or fractional crys-
tallisation plus contamination (AFC). Post-caldera rocks
with high-K calc-alkaline affinity have Sr and Nd isotopes
intermediate between the plagioclase leucititic samples and
the shoshonitic ones, but closer to the latter (Fig. 5), sug-
gesting a possible derivation from shoshonites through
either AFC or mixing plus crystal fractionation (MFC).
Major element mass balance calculation performed on
pre-caldera leucite-bearing rocks having similar initial87Sr/86Sr (from RMN 44 to RMN 45) has provided at the best
an R2 = 1.1 for a fractionation of clinopyroxene (37.9
vol.%) + leucite (15.6 vol.%) + apatite (2.5 vol.%) +
magnetite (13.5 vol.%). This assemblage is compatible with
modal mineralogy of the choose end members, and is con-
firmed by trace element enrichment factors calculated.
A plagioclase (7.7 vol.%) + clinopyroxene (9.2 vol%) +
apatite (0.73 vol.%) + magnetite (6.9 vol.%) assemblage
(R2 = 0.45) is argued to achieve the composition of the most
evolved rocks at MgO levels lower than 2 wt.% (RMN 43),
but differences in the 87Sr/86Sr and 143Nd/144Nd isotopes
argue for open system processes. AFC does not model the
isotopic composition of the most differentiated plagioclase
Table 2 continued
Series Post-caldera: leucite-free shoshonites Post-caldera: leucite free HKCA
Sample RMN 17 RMN 48 RMN 24 RMN 01 RMN 30 RMN 42 RMN 22 RMN 29 RMN 39 RMN 33 RMN 12
Er nd 3.15 3.08 nd 3.10 3.23 3.13 2.61 2.84 2.61 nd
Tm nd 0.439 0.441 nd 0.441 0.464 0.455 0.368 0.405 0.378 nd
Yb 2.06 2.73 2.84 2.86 2.80 2.90 2.91 2.34 2.48 2.51 2.84
Lu nd 0.405 0.414 nd 0.424 0.426 0.435 0.347 0.373 0.373 nd
Hf 3.5 3.88 5.20 5.3 5.04 5.50 5.14 3.47 3.65 3.72 3.5
Ta 0.50 0.70 0.94 1.07 0.96 1.03 1.06 0.70 0.70 0.70 0.69
Pb 9.90 20.6 22.5 23 25.3 33.5 23.6 17.1 20.0 17.8 15
Th 8.9 12.9 18.6 20 19.1 21.1 21.2 8.8 9.5 9.2 9.7
U 2.7 2.7 5.3 6 5.6 6.0 7.1 2.1 2.2 2.2 2
Major elements have been determined by XRF; trace elements by ICP-MS; when in italic they have been determined by XRF and INAA
Contrib Mineral Petrol (2009) 157:41–63 51
123
leucititic sample (RMN 43), whereas it might be explained
by either bulk mixing or mixing plus crystal fractionation
(MFC) between plagioclase leucitites and mafic shoshonites
(Fig. 8).
Shoshonitic rocks show the largest differentiation range
covering the entire MgO spectrum of Roccamonfina
rocks, from trachybasalts to trachytes (Fig. 2). Differen-
tiation occurs with small but significant isotopic variation
suggesting that crystal fractionation plus assimilation
dominated. The differentiation pathways followed by
the0shoshonitic rocks are governed mainly by crystal
fractionation of an assemblage made up by olivine
(4.9%) + clinopyroxene (29.6%) + plagioclase (19.9%) +
magnetite (9.7%) ± biotite and sanidine in the most dif-
ferentiated steps. Applying partition coefficients of
Francalanci et al. (1987) and Foley and Jenner (2004)
AFC has been modelled to account for Sr and Nd isotopic
variations (Fig. 8). According to the geology of the area a
limestone has been taken as contaminant (Mattei et al.
1993; Giordano et al. 1995). In Fig. 8 the AFC modelling
(DePaolo 1981) for Sr/Th versus initial 87Sr/86Sr is
reported. Starting from a mafic parental magmas the entire
trend of shoshonites can be modelled with an r (i.e.
assimilation/crystallisation mass proportions) = 0.2. On
the other hand, it is not possible to derive any plagioclase-
leucititic composition with an AFC process starting from
a mafic shoshonitic end member (Fig. 8).
Regarding late post-caldera leucite-free rocks (HKCA),
they distinctively plot on a further different trend. AFC
starting from a mafic shoshonitic composition does not
account completely for their genesis. In fact an r value
[0.5 is needed (Fig. 8), which would results a far too high
proportion of assimilated material. On the other hand a
mixing process between mafic shoshonite and some pla-
gioclase leucitite magma might account for their genesis.
The possibility of generating such enrichment in the
incompatible trace element contents by crustal assimilation
has been thoroughly discussed and discounted in previous
works (e.g. Conticelli 1998; Murphy et al. 2002). Fur-
thermore, the role of crustal contamination of such
protoliths does not match with the strong degree of silica
undersaturation of ultrapotassic leucite-bearing rocks.
Recently Iacono Marziano et al. (2007) have called for
strong involvement of sedimentary carbonate assimilation
in the Italian rocks to justify the derivation of ultrapotassic
leucite-bearing rocks from shoshonite. This general picture
was already arise by several authors in the early twentieth
century (e.g. Daly 1910; Rittmann 1933) and discounted by
Savelli (1967). On the other hand, Iacono Marziano et al.
(2007), on the basis of experimental data, justify the pas-
sage from shoshonite to either leucititic or plagioclase
leucititic magmas through limestone assimilation plus
clinopyroxene crystallisation. Our calculations (Fig. 8)
clearly show that AFC is an important process in gene-
rating the geochemical and isotopic variation in post-
caldera shoshonitic rocks but cannot reproduce the
transition from post- to pre- caldera products, or vice versa.
Other characteristic of Roccamonfina volcano rocks
argues against such a process. Analogously to Savelli
(1967) we have found that ultrapotassic leucite-bearing
rocks are enriched in incompatible trace elements respect
with leucite-free (i.e. shoshonite and high-K calc-alkaline)
ones, with limestones characterised by the lowest concen-
tration levels (Fig. 9). In addition limestones from
Apennine (Melluso et al. 2003, 2005a, b; Conticelli et al.
2002, 2007, 2008, in press; Boari et al. 2008a, in press)
Fig. 4 Patterns of incompatible trace elements normalised to the
primordial mantle (Sun and Mc Donough 1989) for ultrapotassic
rocks of the Roccamonfina volcano. Element order in the abscissa
follows the increasing compatibility of the elements according to
Hoffman (1996). Note that pre-caldera plagioclase leucitites and post-
caldera leucite-free rocks have similar normalised patterns, but Nb/Ta
values are inverted passing from pre- to post-caldera ones
52 Contrib Mineral Petrol (2009) 157:41–63
123
Ta
ble
3S
r,N
d,
and
Pb
iso
top
eso
nre
pre
sen
tati
ve
sam
ple
fro
mR
occ
amo
nfi
na
Sam
ple
87S
r/86S
r
mea
sure
d
2si
gm
a87S
r/86S
r
init
ial
143N
d/1
44N
d
mea
sure
d
2si
gm
a143N
d/1
44N
d
init
ial
206P
b/2
04P
b207P
b/2
04P
b208P
b/2
04P
b
Pre
-cal
der
a;le
uci
te-b
eari
ng
ult
rap
ota
ssic
rock
s
RM
N4
40
.70
95
33
±0
.00
00
07
0.7
09
52
90
.51
21
52
±0
.00
00
03
0.5
12
15
21
8.7
88
15
.68
93
9.0
48
RM
N1
80
.70
98
37
±0
.00
00
05
0.7
09
83
40
.51
21
67
±0
.00
00
05
0.5
12
16
71
8.8
23
15
.69
83
9.0
52
RM
N4
60
.70
99
91
±0
.00
00
06
0.7
09
98
7n
dn
dn
dn
dn
dn
d
RM
N4
50
.70
98
56
±0
.00
00
07
0.7
09
85
20
.51
21
71
±0
.00
00
04
0.5
12
17
11
8.8
51
15
.70
13
9.0
76
RM
N4
30
.70
92
61
±0
.00
00
07
0.7
09
25
50
.51
21
34
±0
.00
00
07
0.5
12
13
41
8.8
05
15
.68
53
9.0
48
Po
st-c
ald
era;
earl
yp
has
e,sh
osh
on
itic
rock
s
RM
N1
10
.70
66
63
±0
.00
00
08
0.7
06
66
20
.51
23
77
±0
.00
00
07
0.5
12
37
71
9.1
53
15
.68
03
9.1
99
RM
N1
40
.70
66
88
±0
.00
00
07
0.7
06
68
70
.51
23
59
±0
.00
00
09
0.5
12
35
91
9.0
26
15
.66
13
9.1
23
RM
N0
90
.70
67
88
±0
.00
00
04
0.7
06
78
60
.51
23
50
±0
.00
00
04
0.5
12
35
01
8.9
24
15
.67
43
9.0
84
RM
N1
60
.70
66
56
±0
.00
00
03
0.7
06
65
40
.51
23
56
±0
.00
00
10
0.5
12
35
6n
dn
dn
d
RM
N0
40
.70
68
13
±0
.00
00
04
0.7
06
81
20
.51
23
42
±0
.00
00
03
0.5
12
34
2n
dn
dn
d
RM
N1
70
.70
67
62
±0
.00
00
04
0.7
06
76
1n
dn
dn
dn
dn
dn
d
RM
N4
80
.70
68
92
±0
.00
00
07
0.7
06
89
1n
dn
dn
dn
dn
dn
d
RM
N2
40
.70
74
55
±0
.00
00
05
0.7
07
45
40
.51
23
71
±0
.00
00
05
0.5
12
37
11
9.0
69
15
.69
43
9.2
12
RM
N0
10
.70
70
55
±0
.00
00
08
0.7
07
05
4n
dn
dn
dn
dn
dn
d
RM
N3
00
.70
70
31
±0
.00
00
07
0.7
07
03
00
.51
23
69
±0
.00
00
04
0.5
12
36
91
9.0
08
15
.69
33
9.1
68
RM
N4
20
.70
71
23
±0
.00
00
05
0.7
07
12
2n
dn
dn
dn
dn
dn
d
RM
N2
20
.70
69
77
±0
.00
00
07
0.7
06
97
50
.51
23
82
±0
.00
00
03
0.5
12
38
2n
dn
dn
d
Po
st-c
ald
era;
fin
alp
has
e,H
KC
Aro
cks
RM
N2
90
.70
74
92
±0
.00
00
03
0.7
07
49
20
.51
22
77
±0
.00
00
05
0.5
12
27
71
8.8
86
15
.68
63
9.0
88
RM
N3
90
.70
74
88
±0
.00
00
05
0.7
07
48
80
.51
22
70
±0
.00
00
04
0.5
12
27
01
8.8
90
15
.69
53
9.1
01
RM
N3
30
.70
74
76
±0
.00
00
07
0.7
07
47
60
.51
22
65
±0
.00
00
03
0.5
12
26
51
8.8
96
15
.70
03
9.1
18
RM
N1
20
.70
74
92
±0
.00
00
04
0.7
07
49
2n
dn
dn
dn
dn
dn
d
Init
ial
val
ues
hav
eb
een
calc
ula
ted
on
ages
fro
mli
tera
ture
(Co
rtin
iet
al.
19
73;
Fo
rnas
eri
19
85
;R
adic
ati
di
Bro
zolo
etal
.1
98
8);
see
tex
tfo
rfu
rth
erex
pla
nat
ion
Contrib Mineral Petrol (2009) 157:41–63 53
123
have intermediate Sr isotope ratios between plagioclase
leucitites and shoshonitic rocks, precluding any possibility
to derive one from the other by limestone assimilation. It
has been shown indeed, that limestone assimilation by ultra-
potassic magmas has the effect of diluting incompatible
trace elements (Peccerillo 1998, 2005b) due to their
extremely low K and incompatible trace elements contents
(Fig. 9). In addition sedimentary carbonate assimilation
would also modify trace element signature of magmas
imparting extremely high U/Th, which is not observed
(Avanzinelli et al. 2008). By contrast, due to the very low
REE contents, and then of Nd and Pb contents of lime-
stones the trends observed for REE and 143Nd/144Nd and206Pb/204Pb should be the opposite of what observed at
Roccamonfina (Figs. 5, 6).
In summary, the post-caldera MgO-rich leucite-free
magmas, either shoshonitic or high-K calc-alkalic, cannot
represent the parental magma of the entire Roccamonfina
succession. Geochemical and petrographic characteristics
suggest that ultrapotassic plagioclase leucititic magmas and
leucite free magmas, erupted, respectively, during pre- and
post-caldera stages, are not cogenetic and they derive from
different events of partial melting of a variably meta-
somatised upper mantle source.
Origin of ultrapotassic parental magmas
In the light of the above discussion we can safely assume
that the strong fractionation between LILE and HFSE
(Fig. 4) is a primary characteristics of Roman ultrapotassic
leucite-bearing rocks, which has also been observed in
volcanic island arcs where the budget of incompatible trace
elements is clearly dominated by sediment addition (e.g.
Aeolian Arc, Francalanci et al. 1993, 2007; Banda Arc,
Vroon et al. 1993; Sunda arc, Whitford et al. 1979;
Hoogewerff et al. 1997). Depletion of HFSE except Th
(Fig. 4) with respect to LILE is attributed either to the
original fractionation in the sedimentary reservoirs (Fig. 9)
Fig. 5 143Nd/144Nd and initial 87Sr/86Sr versus MgO wt.% for
Roccamonfina rocks
Mafic enclaves in TAP
Tuscan Province
Tuscan Anatectic Province
Apennine Crustal Rocks
Vulture (LuMP)
Pietre Nere
Tyrrhenian Sea Floor
RMP-LD(Latian Districts)
Aeolian Arc RMP-ND(Neapolitan District)
Fig. 6 143Nd/144Nd versus
initial 87Sr/86Sr isotopic
composition for the Italian
potassic and ultrapotassic rocks.
Fields have been drawn on the
basis of data from Conticelli
et al. (1992, 1997, 2002, 2007,
2008, in press), Conticelli
(1998), Pappalardo et al. (1999),
Perini et al. (2004), Avanzinelli
et al. (2008), Boari et al. (2008a,
b, in press) and author’s
unpublished data (e.g., Vulture,
Vesuvius). A blow up of the
inset is reported at the top-righthand side. Symbol size is larger
than analytical error (2r)
54 Contrib Mineral Petrol (2009) 157:41–63
123
recycled into the mantle (Plank and Langmuir 1998) or to
retention of Ta, Nb, Hf, Zr and Ti by a residual phase
during recycled sediment partial melting (Nicholls et al.
1994; Elliott et al. 1997). Th is not readily partitioned into
slab-derived fluids, but can be efficiently enriched in the
metasomatising agent via partial melting of recycled sedi-
ments (Johnson and Plank 1999). Also Pb is efficiently
enriched within the mantle wedge by sediment-derived
metasomatism. The high Th/Nb values shown by plagio-
clase leucititic pre-caldera rocks (Fig. 10) are clearly
suggestive of melt dominated subduction component
(Elliott et al. 1997; Plank 2005). Shoshonites, on the other
hand, show a linear decreasing of this ratio, with values\1,
pointing towards the composition of the within plate alkali
basalts of Pietre Nere (PN end member in Fig. 10) in the
Adriatic foreland (Fig. 1).
Production of silica-undersaturated melts (i.e. leucite-
bearing pre-caldera volcanic rocks) is thought to be due
either to extremely high-P partial melting or to partial
melting under extremely high XCO2conditions of a meta-
somatised mantle source. Most of the geochemical and
mineralogical characteristics of Roccamonfina leucite-
bearing rocks are compatible with partial melting of a
modally metasomatised lithospheric upper mantle similarly
to other volcanic fields of the Roman region (i.e., RMP-
LD; Boari and Conticelli 2007; Boari et al. 2008a,
in press). The same holds true for their extreme enrichment
in Al2O3 which is also testified by the occurrence of modal
plagioclase (Table 1). In this scenario, the CO2-rich com-
ponent might have been acquired during partial melting of
CaCO3-rich subducted marly sediment. Then devolatilisa-
tion of CaCO3 component might provide the CO2 for
increase the XCO2and the necessary CaO to refertilise the
lithospheric refractory source, whereas melts from the
silicoclastic components would have enriched in K and
incompatible elements the mantle source of Roccamonfina
magmas. In Fig. 6 it is clear the decoupling between initial87Sr/86Sr and 143Nd/144Nd with Roman Magmatic Province
pointing to a crustal reservoir with the isotopic composition
intermediate between those of shales and limestones.
Leucite-bearing rocks from Roccamonfina volcano fall
Fig. 7 143Nd/144Nd, and initial 87Sr/86Sr versus 206Pb/204Pb isotopic
compositions for the Italian potassic and ultrapotassic rocks (in
colour) with reported data for the Roccamonfina Volcano (black,
white and grey). Data sources Conticelli et al. (1992, 1997, 2002,
2007, 2008, in press), Conticelli (1998), Pappalardo et al. (1999),
Perini et al. (2004), Avanzinelli et al. (2008), Boari et al. (2008a, b,
in press) and author’s unpublished data (e.g., Vulture, Vesuvius).
TMP Tuscan Magmatic Province, RMP-LD Latian Districts of the
Roman Magmatic Province, RMP-ND Neapolitan District of the
Roman Magmatic Province, LuMP Lucanian Magmatic Province, PSPescosansonesco dykes, PN Punta delle Pietre Nere dykes, LMPlamproites, SHO shoshonites, HKCA high-K calc-alkalic, KAMkamafugites, HKS plagioclase leucitites and leucitites
Fig. 8 Sr/Th versus 87Sr/86Sr for the Roccamonfina volcanic rocks
with reported simulation pathways for AFC and bulk-mixing
differentiation models. Lines for AFC refers to r = 0.2 and p 0.5,
respectively. F = Mm/Mo (final volume of magma/initial volume of
magma); r = assimitared/crystallased rate. Partition coefficient used
are after Francalanci et al. (1987) and Foley and Jenner (2004). Note
that AFC with r = 0.2 is able to model the entire shoshonitic trend,
whereas AFC is not able to model the differentiation within
plagioclase leucitites
Contrib Mineral Petrol (2009) 157:41–63 55
123
along this trend, with isotopic values typical of leucite-
bearing rocks (plagio-leucitites, leucitites, and kamafugi-
tes) of the Roman Magmatic Province but slightly less
enriched in radiogenic Sr (Fig. 6). Avanzinelli et al. (2008)
focussing attention of the southern Roman Province and
using new Sr and Nd isotopes and U–Th disequilibria
modelled the observed compositional variation of MgO-
rich mafic magmas of Southern Roman Province with the
addition to the mantle wedge of a ‘‘marl’’ subducting
sediment assemblage, estimated as a 50:50 mixing between
the clay- and carbonate-rich components. Given the esti-
mated composition of sediment melts, the authors
calculated that less than 5% of recycled sediments melts is
able to reproduce the Sr–Nd isotope variation of the Roman
Province. Roccamonfina high-Mg plagioclase leucititic
rocks from Roccamonfina fit perfectly this simulation. In
Fig. 12 the plot of 208Pb/204Pb versus 206Pb/204Pb varia-
tions is reported for the entire set of Neogene to Quaternary
rocks of the Italian Peninsula and in particular for the
Roccamonfina volcanic rocks. D-DMM, OIB, and CaCO3-
rich bulk sedimentary components with several different
simulations are also reported (Fig. 12). Focussing attention
on ultrapotassic rocks (plagioclase leucitites), the Rocca-
monfina ones fall well within the field of northern volcanic
district of the Roman Province (RMP-LD). Taking into
account a D-DM mantle on one hand, and a bulk sedi-
mentary component enriched in CaCO3, on the other one,
less than 3–5% of recycled sediments melts is able to
reproduce the Pb isotopic isotope variations of the ultra-
potassic rocks of Roccamonfina volcano, but also of the
RMN-LD portion of the Roman Province (Fig. 12).
Transition from ultrapotassic to shoshonitic magmas
The two major issues that remain the centre of debate,
when Roccamonfina volcano is concerned, are the coex-
istence of ultrapotassic leucite-bearing and shoshonitic
rocks in the same volcano, and the link between this shift in
composition and the overall southward chemical variation
observed in Italian volcanism jumping from the Latian
districts (RMP-LD) to the Neapolitan one (RMP-ND) of
the Roman Magmatic Province.
As outlined in other papers (e.g. Peccerillo 2005a;
Avanzinelli et al. 2008) Neapolitan rocks (RMP-ND)
clearly differs from Latian districts rocks (RMP-LD) in at
least three main features: they have (1) lower Sr and higher
Nd and Pb isotope ratios (Peccerillo 2005a, and references
Fig. 10 Th/Nb versus Ta/Nb for the Roccamonfina rocks. Data fields
for Tuscan Magmatic Province (TMP), Roman Magmatic Province
north of Roccamonfina (RMP-LD), Roman Magmatic Province South
of Roccamonfina (RMP-ND), and Lucanian Magmatic Province
(LuMP) are also reported in colour, as well as values for the Punta le
Pietre Nere (PN) and Pescosansonesco (PS) within plate magmatic
rocks from Adriatic plate. Data Sources Conticelli et al. (1992, 1997,
2002, 2004, 2007, 2008, in press), Conticelli (1998), Pappalardo et al.
(1999), Perini et al. (2004), Avanzinelli et al. (2008), Boari et al.
(2008a, b, in press) and author’s unpublished data (e.g., Vulture,
Vesuvius, Middle Latin Valley)
Fig. 9 Patterns of incompatible trace elements normalised to the
primordial mantle (Sun and Mc Donough 1989) for Apennine crustal
rocks (top) and comparison among the compositions of high-Mg
plagioclase-leucitites (pre-caldera), shoshonites (post-caldera), and
limestone from Lepini Mounts (bottom). Note that limestone have
strongly lower normalised values than volcanic rocks, and different
distributions. Assimilation of limestone plus crystal fractionation of
clinopyroxene starting from the shoshonite would have affected
dramatically U/Th, Nb/Ta, Ce/Pb, and Sr/Nd values, which are not
fractionated by clinopyroxene
56 Contrib Mineral Petrol (2009) 157:41–63
123
therein); (2) 238U excess testifying a recent U-enriched
metasomatic event which is not present in the other Latian
volcanic districts (i.e. Avanzinelli et al. 2008); (3) higher
Nb suggesting the involvement of a rather fertile end
member (e.g. OIB pre-metasomatism mantle wedge?—
Beccaluva et al. 1991).
The Roccamonfina volcano is the only volcanic district
where both geochemical and isotopic signatures occur but
temporarily separated. Pre-caldera plagioclase leucitites
(HKS) have compositional and isotopic characteristics
similar to those of the Latian districts (Figs. 10, 11, 12) of
the Roman Magmatic Province (RMN-LD). Post-caldera
shoshonites, on the other hand, have Nd (143Nd/144Nd =
0.512342–0.512382) and Pb (e.g., 206Pb/204Pb = 18.924–
19.153) higher than those of pre-caldera rocks and over-
lapping those of Neapolitan rocks (RMN-ND). Therefore,
we believe it is important to relate the regional shift in the
composition of Italian volcanism with that occurring in the
different phases of the Roccamonfina volcano in order to
make the most of the clues that Roccamonfina volcano
might provide on the overall Italian volcanism. It is clear in
Figs. 7 and 11 that the shoshonitic and the sub-alkaline
basaltic andesitic rocks from Roccamonfina fall always
within the field of Neapolitan rocks (RMP-ND) pointing
towards the composition of Punta Pietre Nere volcanic
rocks, though those of Monte Vulture (Lucanian Magmatic
Province). However, few U–Th isotope data on shoshonites
and sub-alkaline lavas (authors’ unpublished data) show
near equilibrium isotopic composition and no sign of the238U excess characteristic of the Neapolitan region. This
suggests that the recent addition of the U-enriched com-
ponent affecting the Neapolitan region seems not to be
effective beneath Roccamonfina.
The transition from plagioclase leucitites rocks to
shoshonites has to be explained in terms of the general
decrease in incompatible element, the change in Sr–Nd–Pb
isotope and the increase in Nb content (Figs. 10, 11). Two
hypotheses has been proposed to explain this transition: (1)
increasing country rock-vein interaction within the mantle
wedge with increasing contribution of a within plate
Fig. 12 208Pb/204Pb vs. 206Pb/204Pb isotopic compositions for the
Italian potassic and ultrapotassic rocks (in colour) with reported data
for the Roccamonfina Volcano (black, white and gray); for symbols
about Italian rocks see Fig. 7. Data sources Conticelli et al. (1992,
1997, 2002, 2007, 2008, in press), Conticelli (1998), Pappalardo et al.
(1999), Perini et al. (2004), Boari et al. (2008a, b, in press) and
author’s unpublished data (e.g., Vulture, Vesuvius). TMP Tuscan
Magmatic Province, RMP-LD Latian Districts of the Roman
Magmatic Province, RMP-ND Neapolitan District of the Roman
Magmatic Province, LuMP Lucanian Magmatic Province, PS Pesco-
sansonesco dykes, PN Punta delle Pietre Nere dykes. A marlstone has
been taken as the sediment end member (see Avanzinelli et al. 2008
for a thorough discussion). Due to the lack of Pb data on Italian
sediments we used the Pb isotopic composition of sediments
subducting under Sunda arc (Plank and Langmuir 1998) as a proxy;
indeed, the lithologic assemblage subducting under Sunda is made up
by an alternation of limestone and clays, resembling subducting under
Italy. The isotopic composition of Punta Pietre Nere (PN) has been
taken as the within plate component fluxed through slab tearing into
the mantle wedge of the Italian Peninsula. Roccamonfina plagioclase
leucitites samples lie along with other Roman magmas (RMP-LD) on
a mixing curve between D-DMM bulk and Marlstone sediments
(dashed line with crosses). Shoshonites compositions can be repro-
duced by adding to the source of plagioclase leucitites magmas a
variable amount (7–20%, dashed line with dots) of within plate
asthenospheric component. On the contrary, the simple addition of
marlstone sediments to the within-plate astenospheric mantle (dashedline with stars) does not fit the isotope composition of Roccamonfina
shoshonitic rocks
Fig. 11 Zr/Nb vs. 206Pb/204Pb isotopic compositions for the Rocca-
monfina Rocks Data fields for Tuscan Magmatic Province (TMP),
Roman Magmatic Province north of Roccamonfina (RMP-LD),
Roman Magmatic Province South of Roccamonfina (RMP-ND), and
Lucanian Magmatic Province (LuMP) are also reported in colour, as
well as values for the Punta le Pietre Nere (PN) and Pescosansonesco
(PS) within plate magmatic rocks from Adriatic plate. Data sources
Conticelli et al. (1992, 1997, 2002, 2007, 2008, in press), Conticelli
(1998), Pappalardo et al. (1999), Perini et al. (2004), Avanzinelli et al.
(2008), Boari et al. (2008a, b, in press) and author’s unpublished data
(e.g., Vulture, Vesuvius)
Contrib Mineral Petrol (2009) 157:41–63 57
123
component from slab tears (Foley 1992b; Conticelli et al.
2002, 2007); (2) partial melting in different mantle wedge
levels (Peccerillo and Panza 1999).
Metasomatism within the upper mantle usually occurs
along the main flow pathways of metasomatic agents.
Reaction between metasomatic agents and the upper
mantle produced a new mineralogy accommodated in a
vein network (Foley 1992b). In the case of ultrapotassic
magmatism vein network is established within the litho-
spheric portion of the mantle (e.g. Mitchell 2006). The
metasomatic mineralogical assemblage has lower melting
point than surrounding upper mantle (Foley 1992b). When
veined mantle is within a mantle wedge at a destructive
continental plate margin and collision come to end, in the
back of the orogen extension brought to isotherms relaxa-
tion. Upraise of isotherms brought to partially melt the vein
network, which has the lowest melting point of the mantle
wedge; further isotherms relaxation brings also the sur-
rounding mantle to melts and then interaction with pure-
vein melt continuously change the composition of the
produced magmas. An increasing diminution of the alka-
line degree of the magmas and therefore of the total
metasomatic signature within the incompatible trace ele-
ment distribution is observed in some alkaline-ultrapotassic
to potassic associations (i.e. Tuscan Magmatic Province,
Conticelli et al. 2007; Trans Mexican Volcanic Belt, Maria
and Luhr 2008) with increasing melting degree and thus
increasing proportions of country rock over vein-mantle.
In the case of Roccamonfina Volcano we observe a
decreasing alkaline degree and total abundance of incom-
patible elements passing from pre-caldera, leucite-bearing
magmas, to early post-caldera, shoshonitic magmas, till
late post-caldera, high-K calc-alkalic magmas (Figs. 2, 4).
All these characteristics are consistent with the process of
increasing interaction proportion of melts from surrounding
mantle with respect to vein melts (i.e. leucite-bearing
magma). Problems arise, however, when we consider the
large variation in Sr–Nd–Pb isotopes, for simple mass
balance reasons. Given the difference in Sr, Nd and Pb
content of the vein and the surrounding depleted mantle
(Sun and Mc Donough 1989), the isotopic composition of
any resulting melt would be strongly dominated by that of
the vein. Higher degrees of melting and thus higher pro-
portion of country rock would dilute the absolute
concentration of those elements, but hardly change the
isotopic composition of the melt. Another problem arises
from the expected isotopic composition of the surrounding
mantle: its low Sr and high Nd isotope ratios, respectively,
would suite the versus of variation in the shoshonites;
however, a depleted mantle is expected to have developed
low U/Pb and Th/Pb and thus to have an unradiogenic
signature, rather than the radiogenic one necessary to
explain the increase in Pb isotopic ratios towards the
shoshonites (Figs. 10, 11). A high 206Pb/204Pb mantle
component could be envisaged only suggesting the mantle
wedge with an OIB signature prior to metasomatism
(Beccaluva et al. 1991). A fertile OIB-like surrounding
mantle would also have higher trace element composition,
and thus potentially more leverage on the mass balance
proportions of elements between vein and country rock, but
more importantly it would bear high Nb concentration
producing the Nb enrichment observed in the post-caldera
shoshonites. This has been found recently in mantle
xenoliths from Eifel volcanic field.
An OIB-like mantle wedge, however, cannot be sug-
gested also for the ultrapotassic (plagioclase leucitites) pre-
caldera rocks, which clearly follow a mixing trend between
a D-DMM and marlstone sediment (Figs. 7, 12). In the
frame of a veined mantle, it could be argued that the
decrease in Zr/Nb in post-caldera rock reflects their lower
proportion of vein to country rock in the ultrapotassic pre-
caldera rocks, but if mantle wedge had an OIB signature
prior to the metasomatism, it is conceivable that this sig-
nature would be at some extent preserved also within the
vein (Fig. 12).
More information can be obtained from the mineral
chemistry of separated phases in other Italian volcanoes.
Cr-spinel inclusions in olivine crystals from Italian volca-
nic rocks (Boari et al. 2008b, in press) have given clues on
the degree depletion of the pre-metasomatism mantle
beneath Italy. Although no such data are available for
Roccamonfina, olivine-spinel pairs from the ultrapotassic
leucite-bearing rocks from the Latian districts (Perini and
Conticelli 2002; Boari and Conticelli 2007), comparable
with pre-caldera rocks, suggest a highly depleted mantle;
on the opposite a more fertile one is suggested by olivine-
spinel pairs measured in the Neapolitan districts volcanic
rocks (e.g. Conticelli et al. 2004), which can be related to
the post-caldera shoshonites.
In summary trace element ratios, such as Zr/Nb, Th/Nb,
and isotopic values all points to the OIB component similar
to Punta Pietre Nere in the Adriatic foreland (Figs. 7, 10,
11, 12); therefore it is argued that an asthenospheric
component with the trace element and isotopic composi-
tions similar to the source of the Punta Pietre Nere magma
is involved in the genesis of the post-caldera shoshonites.
As outlined, earlier the presence of an astenosperic OIB-
like component in the genesis of the southernmost Italian
magmas (i.e. RMP-ND) had been claimed in previous
studies (Beccaluva et al. 1991; Ayuso et al. 1998; Pecce-
rillo and Panza 1999). According to the interpretation of
Peccerillo and Panza (1999) the OIB-like signature of post
caldera magmas could be interpreted with a metasomatised
source within the mantle wedge located at a different,
deeper and thus asthenospheric, level than that of pre-cal-
dera ones, which would be instead located in the
58 Contrib Mineral Petrol (2009) 157:41–63
123
lithosphere. Here we propose a slight different interpreta-
tion when the asthenospheric, high Zr/Nb and radiogenic
Pb-isotope component is added to the source of ultrapot-
assic plagioclase leucitites successively to their genesis to
generate shoshonites. In the 208Pb/204Pb versus 206Pb/204Pb
diagram (Fig. 12) Roccamonfina shoshonitc rocks do not
plot on a hypothetic mixing line between the PN end-
member and the sedimentary component as expected if
metasomatism occurred at different mantle levels. Instead,
post caldera mixing trend start directly from the pre-caldera
ones moving away toward the PN component, within a
range of 10 and 20% of an OIB-like component added to
the source of plagioclase leucitites. The fact that the OIB-
like component is recorded late in the history of the Roc-
camonfina volcano we might argue for its late arrival
within the mantle wedge after the caldera formation. This
agree also with the chronological differences within the
Roman Magmatic Province being the Nepolitan volcanoes
(RMP-ND) much younger than those of the Latian Districts
(RMP-LD). The oldest shoshonitic event at Roccamonfina
volcano has been dated at 327 ± 24 ka (40Ar/39Ar per-
formed by M.A. Laurenzi 2006 personal communication),
an age comparable to the beginning of magmatism in the
Neapolitan Area (Brocchini et al. 2001).
In summary all the available data on Roccamonfina
volcano suggest similar surrounding mantle for pre- and
post-caldera rocks, but with an increasingly asthenospheric
component late arrival. This would imply that partial
melting occurs within the mantle wedge under high XCO2to
produce ultrapotassic leucite bearing rocks. The subsequent
arrival of the OIB-like astenospheric component changed
the geochemical isotopic compositions of the mantle
source. In addition it increases also heat flow triggering
larger degrees of partial melting that exhaust the sedi-
mentary-derived CO2 providing magmas under low XCO2
partial melting conditions.
The physical processes responsible for the arrival of
asthenospheric material into the metasomatised mantle
wedge can be discussed in relationship with the complex
geodynamics of the Italian area.
The peculiar arcuate morphology of the slab beneath
the Italian peninsula following the south-eastward slab
retreat (Lucente et al. 1999; Wortel and Spakman 2000)
brought to the formation of ruptures of the downgoing slab
(e.g. Faccenna et al. 2001). This phenomenon induces
small slab tears to large plate windows, which might allow
the inflow of sub-slab asthenospheric mantle. U/Th dis-
equilibria measured on Monte Vulture (Lucanian
Magmatic Province; Fig. 1) have shown that influx of hot
asthenospheric mantle material, undergoing adiabatic
melting, invaded the Southernmost sector of the Italian
Mantle wedge in recent times (\350 ka; Avanzinelli et al.
2008). Monte Vulture volcano is part of the Lucanian
Magmatic Province (LuMP) and is located offset with
respect to the Apennine chain (Fig. 1) just at the edge of
the present day Calabrian Arc, site of the still active
subduction beneath the Aeolian Arc (e.g., Francalanci
et al. 2007, and references therein). This suggests that hot
asthenospheric material from the mantle behind or beneath
the subducted slab enters the mantle wedge from the
north-eastern corner of the Ionian subduction (Mattei et al.
2004). The arrival of sub-slab asthenospheric hot material
through slab tears at Monte Vulture is testified by the
composition of Lucanian magmatic rocks, which are
characterised by intermediate geochemical and isotopic
signatures between mantle wedge and within plate (e.g.
Beccaluva et al. 2002; Downes et al. 2002; authors’
unpublished data). Carbonatites with transitional signa-
tures, between within plate and arc magmatism, are also
found at Monte Vulture volcano (D’Orazio et al. 2007).
Here, oblique upraise of the mantle pierced the slab tears
formed as a consequence of the strong bending of the
Adriatic slab during rolling back (Faccenna et al. 2001).
The proximity of Monte Vulture to the trench and thus the
limited vertical extension of the mantle wedge, makes it
the volcano to be interested to higher extent by the by the
asthenospheric flow.
The trace elements and isotopic data of Roccamonfina,
however, are not as extreme as those of Monte Vulture
(Figs. 8, 9). In addition, Monte Vulture plate-window is far
away from the Roccamonfina volcano. However, Lucente
et al. (1999) have shown the presence of a slab tear also in
correspondence of the Ortona-Roccamonfina lineament
(Fig. 1), which might has acted as a preferential way for
sub-slab asthenospheric mantle influx into the mantle
wedge. Then heating provided by the influx might have
triggered larger partial melting of the mantle wedge.
Conclusion
Roccamonfina volcano is a composite volcano character-
ised by a two stage activity: a pre-caldera period
characterised by leucite-bearing rocks (plagioclase-leuci-
tite, HKS) and a post-caldera period with exclusively
leucite-free shoshonites and sub-alkaline basaltic andesites.
Magmas of each period of activity are not genetically
related to those of the other one. Shoshonites and sub-
alkaline basaltic andesites are not comagmatic with pla-
gioclase leucitites (HKS). Within each period of activity
shallow level differentiation mainly driven by crystal
fractionation with minor crustal assimilation occurred.
Leucite-bearing ultrapotassic magmas have been gene-
rated by partial melting of a metasomatised lithospheric
mantle wedge, where a vein network of modally modified
peridotite after metasomatism has been established.
Contrib Mineral Petrol (2009) 157:41–63 59
123
Metasomatic agent is clearly derived from melting and
dehydratation of recycled carbonate-rich sediments.
High-MgO shoshonites and sub-alkaline basaltic ande-
sites have been generated from the interaction between the
lithospheric mantle wedge and an asthenospheric OIB-like
mantle component with very high 143Nd/144Nd,206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb, but consistently
lower Zr/Nb and 87Sr/86Sr than original metasomatised
lithospheric mantle wedge.
The most feasible process capable to add a within plate
asthenospheric OIB component within the sub-italian
mantle wedge is influx from slab tears, from the adjacent
area, as shown by tomographic studies.
Acknowledgments We sincerely appreciate Sergio Chiesa, Angelo
Peccerillo, and Piero Manetti for helps and discussions during the first
field campaign in the late 1980s, Alice Farinelli for helps during the
second field campaign in the early new millenium, Lia M Todaro for
help with AAS analyses, Lorella Francalanci for handling INA
analyses on some samples, and at last but not the least Leone Melluso,
Lorella Francalanci, Simone Tommasini, Giampiero E. Poli, and
Angelo Peccerillo for stirring and focusing discussions. Maurizio
Ulivi provided technical support for isotope analyses. Thoughtful
reviews made by two anonymous peer-reviewers greatly improved the
original manuscript. Editorial managing by Tim Grove is greatly
appreciated. Financial support was provided by Firenze-Perugia Ph.D.
consortium during the early field campaign (1986–1987), by FIRB
2001 (grant # RBAU01FX8M_003) for the final field campaign
(2003) and analytical work, and PRIN 2007 (grant #
2007NS22NZ_005), for the final modelling.
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