The Campanian Ignimbrite (southern Italy) geochemical zoning: insight on the generation of a super-eruption from catastrophic differentiation and fast withdrawal

More than ca 100 km3 of nearly homogeneous
crystal-poor phonolite and ca 100 km3 of slightly zoned
trachyte were erupted 39 ka during the Campanian
Ignimbrite super eruption, the most powerful in the Neapolitan
area. Partition coefficient calculations, equilibrium
mineral assemblages, glass compositions and texture were
used to reconstruct compositional, thermal and pressure
gradients in the pre-eruptive reservoir as well as timing and
mechanisms of evolution towards magma chamber overpressure
and eruption. Our petrologic data indicate that a
wide sill-like trachytic magma chamber was active under
the Campanian Plain at 2.5 kbar before CI eruption.
Thermal exchange between high liquidus (1199 C)
trachytic sill and cool country rocks caused intense
undercooling, driving a catastrophic and fast (102 years) in
situ fractional crystallization and crustal assimilation that
produced a water oversaturated phonolitic cap and an
overpressure in the chamber that triggered the super
eruption. This process culminated in an abrupt reservoir
opening and in a fast single-step high decompression.
Sanidine phenocrysts crystal size distributions reveal high differentiation rate, thus suggesting that such a sill-like
magmatic system is capable of evolving in a very short
time and erupting suddenly with only short-term warning.

Asimow PD, Ghiorso MS (1998) Algorithmic modifications extending
MELTS to calculate subsolidus phase relations. Am Mineral
83:1127–1131
Auger E, Gasparini P, Virieux J, Zollo A (2001) Seismic evidence of
an extended magmatic sill under Mt. Vesuvius. Science
294:1510–1512
Bachmann O, Bergantz GV (2003) Rejuvenation of the Fish Canyon
magma body: a window into the evolution of large-volume
silicic magma system. Geology 31:789–792
Bachmann O, Bergantz GW (2004) On the origin of crystal-poor
rhyolites: extracted from batholithic crystal mushes. J Petrol
45:1565–1582
Barberi F, Innocenti F, Lirer L, Munno R, Pescatore TS, Santacroce R
(1978) The Campanian Ignimbrite: a major prehistoric eruption
in the Neapolitan Area (Italy). Bull Volcanol 41(1):10–22 Blower JD, Keating JP, Mader HM, Phillips JC (2001) Inferring
volcanic degassing processes from vesicle size distributions.
Geophys Res Lett 28:347–350
Bohrson WA, Spera FJ, Fowler SJ, Belkin HE, De Vivo B., Rolandi
G (2006) Petrogenesis of the Campanian Ignimbrite: implications
for crystal-melt separation and open-system processes
from major and trace elements and Th (?) isotopic data. In: De
Vivo B (ed) Volcanism in the Campania Plain: Vesuvius,
Campi Flegrei and Ignimbrites. Developments in Volcanology
9, pp 249–288
Bowen NL (1928) The evolution of igneous rocks. Dover, New York,
p 332
Brophy JG, Dreher ST (2000) The origin of composition gaps at
South Sister Volcano, Central Oregon: implications for fractional
crystallization processes beneath active calc-alkaline
volcanoes. J Volcanol Geotherm Res 102:287–307
Carey S, Sparks RSJ (1986) Quantitative models of the fallout and
dispersal of tephra from volcanic eruption columns. Bull
Volcanol 48:109–125
Carroll MR, Blank J (1997) Solubility of water in phonolitic melts.
Am Mineral 82:1111–1115
Cashman KV (1992) Groundmass crystallization of Mount St. Helens
dacite, 1980–1986: a tool for interpretation shallow magmatic
processes. Contrib Mineral Petrol 109:431–449
Cashman KV, McConnell SM (2005) Multiple levels of magma
storage during the 1980 summer eruptions of Mount St. Helens,
WA. Bull Volcanol 68:57–75
Civetta L, Orsi G, Pappalardo L, Fisher RV, Heiken G, Ort M (1997)
Geochemical zoning, mingling, eruptive dynamics and depositional processes - The Campanian Ignimbrite, Campi
Flegrei caldera, Italy. J Volcanol Geotherm Res 75:183–219
Cornell W, Carey S, Sigurdsson H (1983) Computer simulation of
transport and deposition of the Campanian Y-5 Ash. In: Sheridan
MF, Barberi F (eds) Explosive volcanism. Elsevier, Amsterdam,
pp 89–109
Couch S (2003) Experimental investigation of crystallization kinetics
in a haplogranite system. Am Mineral 88:1471–1485
De Campos CP, Dingwell DB, Fehr KT (2004) Decoupled convection
cells from mixing experiments with alkaline melts from Phlegrean
Fields. Chem Geol 213:227–251
De Natale G, Troise C, Pingue F, Mastrolorenzo G, Pappalardo L,
Battaglia M, Boschi E (2006) The Campi Flegrei Caldera:
unrest mechanisms and hazards. In: Troise C, De Natale G,
Kilburn CRJ (eds) Mechanisms of activity and unrest at large
calderas. Geological Society, London, Special Publications
269:25–45
De Vivo B, Rolandi G, Gans PB, Calvert A, Bohrson W, Spera FJ,
Belkin HE (2001) New constraints on the pyroclastic eruptive
history of the Campanian volcanic Plain (Italy). Mineral Petrol
73:47–65
Deino AL, Orsi G, de Vita S, Piochi M (2004) The age of the
Neapolitan yellow tuff caldera-forming eruption (Campi Flegrei
caldera, Italy) assessed by 40Ar/39Ar dating method. J Volcanol
Geotherm Res 133:157–170
Di Girolamo P (1970) Differenziazione gravitativa e curve isochimiche
nella ‘‘Ignimbrite Campana’’ (Tufo Grigio Campano auct.).
Rend Soc Ital Mineral Petrol 26:1–45
Di Girolamo P, Ghiara MR, Lirer L, Munno R, Rolandi G, Stanzione
D (1984) Vulcanologia e petrologia dei Campi Flegrei. Boll Soc
Geol Ital 103:349–413
Di Matteo V, Carroll MR, Beherens H, Vetere F, Brooker RA (2004)
Water solubility in trachytic melts. Chem Geol 213:187–196
Dvorak JJ, Mastrolorenzo G (1991) History of vertical movement in
Pozzuoli Bay, Southern Italy: the result of regional extension
related to evolution of the Tyrrhenian Sea and of local volcanic
activity. Am Spec pap 263, p 47
Fedele F, Giaccio B, Isaia R, Orsi G (2002) Ecosystem impact of the
Campanian Ignimbrite eruption in Late Pleistocene Europe. Quat
Res 57:420–424
Fisher RV, Orsi G, Ort M, Heiken G (1993) Mobility of a largevolume
pyroclastic flow—emplacement of the Campanian
Ignimbrite, Italy. J Volcanol Geotherm Res 56:205–220
Folch A, Codina R, Martı` J (2001) Numerical modeling of magma
withdrawal during explosive caldera-forming eruptions. J Geophys
Res 106:16163–16175
Fowler SJ, Spera FJ, Bohrson WA, Belkin HE, De Vivo B (2007)
Phase equilibria constraints on the chemical and physical
evolution of the Campanian Ignimbrite. J Petrol 48:459–493
Francalanci L, Peccerillo A, Poli G (1987) Partition coefficients for
minerals in potassium-alkaline rocks: data from Roman province
(Central Italy). Geochem J 21:10
Fuhrman ML, Lindsley DH (1988) Ternary-feldspar modelling and
thermometry. Am Mineral 73:201–215
Gardner JEand Denis M-H (2004) Heterogeneous bubble nucleation
on Fe–Ti oxide crystals in high-silica rhyolitic melts. Geochim
Cosmochim Acta 68:3587–3597
Gardner JE, Hilton M, Carroll MR (1999) Experimental constraints
on degassing of magma: isothermal bubble growth during
continuous decompression from high pressure. Earth Planet Sci
Lett 168:201–218
Ghiorso MS, Sack RO (1995) Chemical mass transfer in magmatic
processes IV. A revised and internally consistent thermodynamic
model for the interpolation and extrapolation of liquid–solid
equilibria in magmatic systems at elevated temperatures and
pressures. Contrib Mineral Petrol 119:197–212 Hammer JE, Cashman KV, Hoblit RP, Newman S (1999) Degassing
and microlite crystallization during pre-climatic events of the
1991 eruption of Mt. Pinatubo, Philippines. Bull Volcanol
60:355–380
Hawkeswort CJ, Blake S, Evans P, Hughes R, Macdonald R, Thomas
LE, Turner SP, Zellmer G (2000) Time scales of crystal
fractionation in magma chambers—integrating physical, isotopic
and geochemical perspectives. J Petrol 41:991–1006
Higgins MD (1996a) Magma dynamics beneath Kameni volcano,
Greece, as revealed by crystal size and shape measurements.
J Volcanol Geotherm Res 70:37–48
Higgins MD (1996b) Crystal size distributions and other quantitative
textural measurements in lavas and tuff from Mt Taranaki
(Egmont volcano), New Zealand. Bull Volcanol 58:194–204
Higgins MD (2000) Measurement of crystal size distributions. Am
Mineral 85:1105–1116
Higgins MD (2002) Closure in crystal size distributions (CSD),
verification of CSD calculations, and the significance of CSD
fans. Am Mineral 87:171–175
Hildreth W, Wilson CJN (2007) Compositional zoning of the Bishop
Tuff. J Petrol 48:951–999
Improta L, Corciulo M (2006) Controlled source nonlinear tomography:
a powerful tool to constrain tectonic models of the
Southern Apennines orogenic wedge, Italy. Geology 34:941–944
Jaupart C, Allegre CJ (1991) Gas content, eruption rate and
instabilities of eruption regime in silicic volcanoes. Earth Planet
Sci Lett 102:413–29
Johnston-Lavis HF (1889) Report of the committee appointed for the
investigation of the volcanic phenomena of Vesuvius and its
neighbourough. Royal Society, London
Klug C, Cashman KV (1994) Vesiculation of May 18, 1980 Mount St.
Helens magma Geology 22:468–472
Larsen J, Gardner J (2004) Experimental study of water degassing
from phonolite melts: implications for volatile oversaturation
during magmatic ascent. J Volcanol Geotherm Res 134:109–124
Lemarchand F, Villemant B, Calas G (1987) Trace element distribution
coefficients in alkaline series. Geochim Cosmochim Acta
51:1071–1081
Lirer L, Luongo G, Scandone R (1987) On the volcanological
evolution of Campi Flegrei. EOS. Trans Am Geophys Union
68:226–234
Mangan MT, Mastin LG, Sisson T (2004) Gas evolution in eruptive
conduits: combining insights from high temperature and pressure
decompression experiments with steady-state flow modeling.
J Volcanol Geotherm Res 129:23–36
Mangan MT, Sisson T (2000) Delayed, disequilibrium degassing in
rhyolite magma: decompression experiments and implications
for explosive volcanism. Earth Planet Sci Lett 183:441–455
Marianelli P, Sbrana A, Proto M (2006) Magma chamber of the
Campi Flegrei supervolcano at the time of eruption of the
Campanian Ignimbrite. Geology 34:937–940
Marsh B (1988) Crystal size distribution (CSD) in rocks and the
kinetics and dynamics of crystallization I. Theory. Contrib
Mineral Petrol 99:277–291
Marsh BD (2002) On bimodal differentiation by solidification front
instability in basaltic magmas, part 1: basic mechanism.
Geochim Cosmochim Acta 66:2211–2299
Mason BG, Pyle DM, Oppenheimer C (2004) The size and frequency of
the largest explosive eruptions on earth. Bull Volcan 66:735–748
Mastrolorenzo G, Pappalardo L (2006) Magma degassing and
crystallization processes during eruptions of high-risk Neapolitan
volcanoes: evidence of common equilibrium rising processes in
alkaline magmas. Earth Planet Sci Lett 250:164–181
McBirney AR, Baker BH, Nilson RH (1985) Liquid fractionation: I.
Basis principles and experimental simulations. J Volcanol
Geotherm Res 24:l–24 McCoy FW, Cornell W (1990) Volcaniclastic sediments in the
Tyrrhenian Basin. Proc Ocean Drill Program 107:291–306
Michaut C, Jaupart C (2006) Ultra-rapid formation of large volumes
of evolved magma. Earth Planet Sci Lett 250:38–52
Melnik O, Barmin AA, Sparks RSJ (2005) Dynamics of magma flow
inside volcanic conduits with bubble overpressure buildup and
gas loss through permeable magma. J Volcanol Geothem Res
143:53–68
Morgan DJ, Blake S and Rogers NW (2003) Crystallization rate and
residence times of sanidine phenocrysts in the AD 472 (Pollena)
eruption of Vesuvius. Geophysical Research Abstracts, Vol 5,
09352, European Geophysical Society 2003
Morgan DJ, Blake S, Rogers NW, De Vivo B, Rolandi G, Davidson
JP (2006) Magma chamber recharge at Vesuvius in the century
prior to the eruption of AD 79 Geology 34:845–848
Morimoto N (1988) Nomenclature of pyroxenes. Mineral Mag
52:535–550
Mourtada-Bonnefoi CC, Laporte D (2004) Kinetics of bubble
nucleation in a rhyolitic melt: an experimental study of the
effect of ascent rate. Earth Planet Sci Lett 218:521–537
Nimis P (1999) Clinopyroxene geobarometry of magmatic rocks. Part
2. Structural geobarometers for basic to acid, tholeiitic and
mildly alkaline magmatic systems. Contrib Mineral Petrol
135:62–74
Ort M, Orsi G, Pappalardo L, Fisher RV (2003) Anisotropy of
magnetic susceptibility studies of depositional processes in the
Campanian Ignimbrite, Italy. Bull Volcanol 65:55–72
Pappalardo L (1994) Chemostratigrafia del deposito dell’Ignimbrite
Campana, PhD thesis
Pappalardo L, Civetta L, de Vita S, Di Vito MA, Orsi G, Carandente
A, Fisher RV (2002)a Timing of magma extraction during the
Campanian Ignimbrite eruption (Campi Flegrei caldera).
J Volcanol Geotherm Res 114:479–497
Pappalardo L, Piochi M, D’Antonio M, Civetta L, Petrini R, (2002)b
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 43:1415–1434
Proussevitch A, Sahagian DL, (2005), Bubbledrive-1: A numerical
model of volcanic eruption mechanisms driven by disequilibrium
magma degassing. J Volcanol Geotherm Res 143:89–111
Rampino MR, Self S (1992) Volcanic winter and accelerated
glaciation following the Toba super-eruption. Nature 359:50–52
Rosi M, Sbrana A (1987) Phlegrean Fields. CNR, ‘‘Quaderni de La
Ricerca Scientifica’’ 114:1–175
Scacchi A (1887) Catalogo dei minerali vesuviani con la notizia della
loro composizione e del loro giacimento. Lo Spettatore del
Vesuvio e dei Campi Flegrei 65–75
Scandone R, Bellucci F, Lirer L, Rolandi G (1991) The structure of
the Campanian Plain and the activity of Neapolitan volcanoes.
J Volcanol Geotherm Res 48:1–31
Schiano P, Clocchiatti R, Ottolini L, Sbrana A (2004) The relationship
between potassic, calc-alkaline and Na-alkaline magmatism
in South Italy volcanoes: a melt inclusion approach. Earth Planet
Sci Lett 220:121–137
Seymour St. KChristanis K, Bouzinos A, Papazisimou S, Papatheodorou
G, Moran E, Denes G (2004) Tephrostratigraphy and tephrochronology in the Philippi peat basin, Macedonia, Northern
Hellas (Greece). Quat Int 121:53–65
Signorelli S, Vaggelli G, Francalanci L, Rosi M (1999) Origin of
magmas feeding the Plinian phase of the Campanian Ignimbrite
eruption, Phlegrean Fields (Italy): constraints based on matrixglass
and glass-inclusion compositions. J Volcanol Geotherm
Res 91:199–220
Spera FJ, Bohrson W (2001) Energy-constrained open-system
magmatic processes I: general model and energy-constrained
assimilation and fractional crystallization (EC-AFC) formulation.
J Petrol 42(5):999–1018
Spera FJ, Oldenburg CM, Christiensen C, Todesco M (1995)
Simulations of convection with crystallization in the system
KAlSi2O6–CaMgSi2O6: implications for compositionally zoned
magma bodies. Am Mineral 40:1188–1207
Sun S, McDonough WF (1989) Chemical and isotopic systematics of
oceanic basalts: implications for mantle composition and
processes. In: Saunders AD, Norry MJ (eds) Magmatism in the
ocean basins. Spec Pub Geol Soc, London 42:313–346
Thunell R, Federman A, Sparks S, Williams D (1979) The age, origin
and volcanological significance of the Y-5 ash layer in the
Mediterranean. Quat Res 12:241–252
Ton-That T, Singer B, Paterne M (2001) 40Ar/39Ar dating of latest
Pleistocene (41 ka) marine tephra in the Mediterranean Sea:
implications for global climate records. Earth Planet Sci Lett
184:645–658
Toramaru A (2006) BND (bubble number density) decompression
rate meter for explosive volcanic eruptions. J Volcanol Geotherm
Res 154:303–316
Turner S, George R, Jerram DA, Carpenter N, Hawkesworth C (2003)
Case studies of plagioclase growth and residence times in island
arc lavas from Tonga and the lesser Antilles, and a model to
reconcile discordant age information. Earth Planet Sci Lett
214:279–294
Turner SP, George RMM, Evans PJ, Hawkesworth CJ, Zellmer GF
(2000) Time scales of magma formation, ascent and storage
beneath subduction zone volcanoes. Philos Trans R Soc Lond A
358:1443–1464
Villemant B (1988) Trace element evolution in the Phlegraean Fields
(Central Italy): fractional crystallization and selective enrichment.
Contrib Mineral Petrol 98:169–183
Vollmer R, Johnston K, Ghiara MR, Lirer L, Munno R (1981)
Sr-isotope geochemistry of megacrysts from continental rift and
converging plate margin alkaline volcanism in South Italy.
J Volcanol Geotherm Res 11:317–327
Webster JD, Raia R, Tappen C, De Vivo B (2003) Pre–eruptive
geochemistry of the ignimbrite-forming magmas of the Campanian
Volcanic Zone, Southern Italy, determined from silicate
melt inclusions. Mineral Petrol 79:99–125
Wholetz K, Civetta L, Orsi G (1999) Thermal evolution of the
Phlegraean magmatic system. J Volcanol Geotherm Res 91:381–
414
Wo¨rner G, Beusen JM, Duchateau N, Gijbels R, Schmincke HU
(1983) Trace element abundance and mineral/melt distribution
coefficients in phonolites from the Laacher See Volcano
(Germany). Contrib Mineral Petrol 84:152–173