A continuous palaeosecular variation record of the last four millennia from the Augusta Bay (Sicily, Italy)

We present a high-resolution palaeomagnetic and rock magnetic study of two cores, MS06
and MS06-SW (6.7 and 1.1 m long, respectively), collected at 72 m below sea level in the
Augusta Bay shelf (Eastern Sicily, Ionian Sea, Italy) about 2.3 kmfrom the coastline. Geophysical
surveying carried out in the sampling area highlighted the presence of a homogeneous
sedimentary sequence that most likely was deposited after the Last Glacial Maximum and
was not affected by anthropogenic disturbances. The two cores penetrated a monotonous mud
sedimentary sequence, interrupted at ∼3 m depth by a 3–4-cm-thick volcanic sandy layer that
is correlated with the tephra fallout deposit produced by the 122 BC plinian eruption of Mt
Etna. This tephra, along with radiocarbon dating of nine marine shells and with radioactive
tracers for the uppermost 0.3 m (210Pb and 137Cs), provide the chronological constraints for
the stratigraphic sequence that resulted younger than 4500 yr BP.
Palaeomagnetic and rock magnetic data show that the sample sequence is magnetically homogeneous.
A single peak of high magnetic mineral concentration is present and corresponds
to the volcanic sandy layer. Palaeomagnetic data allowed the identification of a well-defined
characteristic remanent magnetization that provides a high-resolution record of palaeosecular
variation (PSV) at the sampling site. The reconstructed PSV curve is in good agreement with
the available regional reference PSV curves and with the prediction from recent PSV modelling
for Europe. The palaeomagnetic data obtained in this study on the one hand support
and refine the age model for the cores, derived from other independent constraints, and on the
other hand provide an original high-resolution PSV curve that can serve as a reference for the
central Mediterranean over the last 4 ka.

Anson, G.L. & Kodama K.P., 1987. Compaction-induced shallowing of
the post-depositional remanent magnetization in a synthetic sediment,
Geophys. J. R. astr. Soc., 88, 7–23.
Barletta, F., St-Onge, G., Stoner, J.S., Lajeunesse, P. & Locat, J., 2010. A
high-resolution Holocene paleomagnetic secular variation and relative
paleointensity stack from eastern Canada, Earth planet. Sci. Lett., 298,
162–174.
Bellucci, L.G., Frignani, M., Cochran, J.K., Albertazzi, S., Zaggia, L.,
Cecconi, G. & Hopkins, H., 2007. 210Pb and 137Cs as chronometers
for salt marsh accretion in the Venice Lagoon: links to flooding frequency
and climate change, J. Environ. Radioact., 97, 85–102.
Bleil, U. & von Dobeneck, T., 1999. Geomagnetic events and relative paleointensity
records: clues to high-resolution paleomagnetic chronostratigraphies
of Late Quaternary marine sediments?, in Use of Proxies in
Paleoceanography: Examples from the South Atlantic, pp. 635–654, eds
Fischer G. & Wefer G., Springer, New York.
Blow, R.A. & Hamilton, N., 1978. Effect of compaction on the acquisition
of a detrital remanent magnetization in fine-grained sediments, Geophys.
J. R. astr. Soc., 52, 13–23.
Bloxham, J. & Gubbins, D., 1985. The secular variation of Earth’s magnetic
field, Nature, 317, 777–781.
Bloxham, J. & Jackson, A., 1992. Time-dependent mapping of the magnetic
field at the core-mantle boundary, J. geophys. Res., 97, 19 537–19 563.
Chadima, M. & Hrouda, F., 2006. Remasoft 3.0–a user-friendly paleomagnetic
data browser and analyzer, Travaux G´eophysiques, XXVII, 20–21.
Coltelli, M., Del Carlo, P. & Vezzoli, L. 1998. The discovery of a Plinian
basaltic eruption of Roman age at Mt. Etna, Geology, 26, 1095–1098.
Dal Forno, G. & Gasperini, L., 2008. ChirCor: a new tool for generating
synthetic chirp-sonar seismograms, Comput. Geosci., 34, 103–114.
De Martini, P.M., Barbano, M.S., Smedile, A., Gerardi, F., Pantosti, D., Del
Carlo, P. & Pirrotta, C., 2010. A unique 4000 year long geological record
of multiple tsunami inundations in the Augusta Bay (eastern Sicily, Italy),
Marine Geol., 276, 42–57.
Donadini, F., Korte, M. & Constable, C.G., 2009. Geomagnetic field for
0–3 ka: 1. New data sets for revised global models, Geochem. Geophys.
Geosyst., 10, Q06007, doi:10.1029/2008GC002295.
Frank, U., Nowaczyk, N.R., Negendank, J.F.W. & Melles, M., 2002. A paleomagnetic
record from Lake Lama, Northern Central Siberia, Phys. Earth
planet. Int., 133, 3–20.
Gasperini, L. & Stanghellini, G., 2009. SEISPRHO: an interactive computer
program for processing and interpretation of high-resolution seismic reflection
profiles, Comput. Geosci., 35, 1497–507.
Hagstrum, J.T. & Champion, D.E., 2002. A Holocene paleosecular variation
record from 14C-dated volcanic rocks in western North America, J.
geophys. Res., 107(B1), 2025, doi:10.1029/2001JB000524.
Haltia-Hovi, E., Nowaczyk, N. & Saarinen, T., 2010. Holocene palaeomagnetic
secular variation recorded in multiple lake sediments cores from
eastern Finland, Geophys. J. Int., 180, 609–622.
Holme, R. & Olsen, N., 2006. Core surface flow modelling from highresolution
secular variation, Geophys. J. Int., 166, 518–528.
Hyodo, M., 1984. Possibility of reconstruction of the past geomagnetic field
from homogeneous sediments, J. Geomagn. Geoelectr., 36, 45–62.
Iorio, M., Sagnotti, L., Angelino, A., Budillon, F., D’Argenio, B., Dinar`es-
Turell, J., Macr`ı, P., & Marsella, E., 2004. High resolution petrophysical
and palaeomagnetic study of Late Holocene Shelf Sediments, Salerno
Gulf, Tyrrhenian Sea, Holocene, 14, 417–425.
Jackson, A., Jonkers, R.T. &Walker,M.R., 2000. Four centuries of geomagnetic
secular variation from historical records, Phil. Trans. R. Soc. Lond.
A, 358, 957–990.
King, R.F., 1955. The remanent magnetism of artificially deposited sediments,
Mon. Not. R. astr. Soc., 7, 115–134.
King, J.W., Banerjee, S.K., Marvin, J.A.&O¨ zdemir, O¨ ., 1982.Acomparison
of different magnetic methods for determining the relative grain size of
magnetite in natural materials: some results from lake sediments, Earth
planet. Sci. Lett., 59, 404–419.
Kirschvink, J.L., 1980. The least-squares line and plane and the analysis of
paleomagnetic data, Geophys. J. R. astr. Soc., 62, 699–718.
Knudsen, M.F., Riisager, P., Donadini, F., Snowball, I., Muscheler, R., Korhonen,
K. & Pesonen, L.J., 2008. Variations in the geomagnetic dipole
moment during the Holocene and the past 50 kyr, Earth planet. Sci. Lett.,
272, 319–329.
Korte, M., & Constable C.G., 2005. Continuous geomagnetic field models
for the past 7 millennia: 2. CALS7K, Geochem. Geophys. Geosyst., 6,
Q02H16, doi:10.1029/2004GC000801.
Korte, M., Donadini, F. & Constable, C.G., 2009. Geomagnetic field for 0–3
ka: 2. A new series of time-varying global models, Geochem. Geophys.
Geosyst., 10, Q06008, doi:10.1029/2008GC002297.
Kristj´ansd´ottir, G.B., Stoner, J.S., Jennings, A.E., Andrews, J.T.&Gr¨onvold,
K., 2007. Geochemistry of Holocene cryptotephras from the North Iceland
Shelf (MD99–2269): intercalibration with radiocarbon and palaeomagnetic
chronostratigraphies, Holocene, 17, 155–176.
Leslie, B.W., Lund, S.P. & Hammond, D.E., 1990a. Rock magnetic evidence
for the dissolution and authigenic growth of magnetic minerals
within anoxic marine sediments of the California continental borderland,
J. geophys. Res., 95, 4437–4452.
Leslie, B.W., Hammond, D.E., Berelson, W.M. & Lund, S.P., 1990b. Diagenesis
in anoxic sediments from the California continental boreland and
its influence on Iron, Sulfur, and Magnetite behavior, J. geophys. Res., 95,
4453–4470.
Lund, S., 2007. Paleomagnetic secular variation, in Encyclopedia of Geomagnetism
and Paleomagnetism, pp. 766–776, eds Gubbins, D. &
Herrero-Bervera, E., Springer, Dordrecht.
Magagnoli, A. & Mengoli, M., 1999. Un brevetto CNR per la
campionatura dei fondali marini, Ricerca & Futuro, 14, 67–68
(http://www.area.fi.cnr.it/r&f/n14/magnoli.htm)
Maher, B., 1988. Magnetic properties of some synthetic submicron magnetites,
Geophys. J., 94, 83–86.
Mitra, R. & Tauxe, L., 2009. Full vector model for magnetization in sediments,
Earth planet. Sci. Lett., 286, 535–545.
Nilsson, A., Snowball, I.,Muscheler, R. & Uvo, C. B., 2010, Holocene geocentric
dipole tilt model constrained by sedimentary paleomagnetic data,
Geochem. Geophys. Geosyst., 11, Q08018, doi:10.1029/2010GC003118.
Noel, M. & Batt, C.M., 1990. A method for correcting geographically separated
remanence directions for the purpose of archeomagnetic dating,
Geophys. J. Int., 102, 753–756.
Pav´on-Carrasco, F. J., Osete, M.L., Torta, J.M. & Gaya-Piqu´e, L.R., 2009.
A regional archeomagnetic model for Europe for the last 3000 years,
SCHA.DIF.3K: applications to archeomagnetic dating, Geochem. Geophys.
Geosyst., 10, Q03013, doi:10.1029/2008GC002244.
Ramsey, B.C., 2009. Bayesian analysis of radiocarbon dates, Radiocarbon,
51(1), 337–360.
Reimer, P.J. & Reimer, R.W., 2001. A marine reservoir correction
database and on-line interface, Radiocarbon, 43, 461–463. [suppl.
mat.URL:http://www.calib.org)].
Reimer, P.J. et al., 2009. IntCal09 and Marine09 radiocarbon age calibration
curves, 0–50,000 years cal BP, Radiocarbon, 51(4), 1111–1150.
Roberts, A.P., 2006. High-resolution magnetic analysis of sediment
cores: strengths, limitations and strategies for maximizing the value
of long-core magnetic data, Phys. Earth planet. Int., 156, 162–
178.
Roberts, A.P. & Winklhofer, M., 2004. Why are geomagnetic excursions
not always recorded in sediments? Constraints from post-depositional
remanent magnetization lock-in modelling, Earth planet. Sci. Lett., 227,
345–359. Rolph, T.C. & Shaw, J., 1986. Variations of the geomagnetic field in Sicily,
J. Geomagn. Geoelectr., 38, 1269–1277.
Rolph, T.C., Vigliotti, L. & Oldfield, F., 2004. Mineral magnetism and
geomagnetic secular variation of marine and lacustrine sediments from
central Italy: timing and nature of local and regional Holocene environmental
change, Quat. Sci. Rev., 23, 1699–1722.
Sagnotti, L., Budillon, F., Dinar`es-Turell, J., Iorio, M. & Macr`ı, P.,
2005. Evidence for a variable paleomagnetic lock-in depth in the
Holocene sequence from the Salerno Gulf (Italy): implications for
‘high-resolution’ paleomagnetic dating, Geochem. Geophys. Geosyst., 6,
Q11013, doi:10.1029/2005GC001043.
Smedile, A. et al., 2010. Possible tsunami signatures from an integrated
study in the Augusta Bay offshore (Eastern Sicily – Italy), Mar. Geol.,
submitted.
Snowball, I., Zill´en, L., Ojala, A., Saarinen, T. & Sandgren, P., 2007.
FENNOSTACK and FENNORPIS: varve dated Holocene paleomagnetic
secular variation and relative palaeointensity stacks for Fennoscandia,
Earth planet. Sci. Lett., 255, 106–116.
Speranza, F., Pompilio, M. & Sagnotti, L., 2004. Paleomagnetism of spatter
lavas from Stromboli volcano (Aeolian Islands, Italy): implications
for the age of paroxysmal eruptions, Geophys. Res. Lett., 31, doi:
10.1029/2003GL018944, 2004.
Speranza, F., Branca, S., Coltelli, M., D’Ajello Caracciolo, F. & Vigliotti,
L., 2006. How accurate is ‘‘paleomagnetic dating’’? New evidence
from historical lavas from Mount Etna, J. geophys. Res., 111, B12S33,
doi:10.1029/2006JB004496.
Speranza, F., Pompilio, M., D’Ajello Caracciolo, F. & Sagnotti, L.,
2008. Holocene eruptive history of the Stromboli volcano: constraints
from paleomagnetic dating, J. geophys. Res., 113, B09101,
doi:10.1029/2007JB005139.
St-Onge, G., Stoner, J.S. & Hillaire-Marcel, C., 2003. Holocene paleomagnetic
records from the St. Lawrence Estuary, eastern Canada: centennial to
millennial-scale geomagnetic modulation of cosmogenic isotopes, Earth
planet. Sci. Lett., 209, 113–130.
Tanguy, J.-C., Bucur, I. & Thompson J.F.C., 1985. Geomagnetic secular
variation in Sicily and revised ages of historic lavas from Mount Etna,
Nature, 318, 453–455.
Thompson, R. & Barraclough, D.R., 1982. Geomagnetic secular variation
based on Spherical Harmonic and Cross Validation analyses of
historical and archaeomagnetic data, J. Geomagn. Geoelectr., 34, 245–
263.
Turner, G.M. & Thompson, R., 1981. Lake sediment record of the geomagnetic
secular variation in Britain during Holocene times, Geophys. J., 65,
703–725.
Turner, G.M. & Thompson, R., 1982. Detransformation of the British geomagnetic
secular variation record for Holocene times, Geophys. J., 70,
789–792.
Verosub, K.L., 1977. Depositional and postdepositional processes in the
magnetization of sediments, Rev. Geophys., 15, 129–143.
Verosub, K.L., 2000. Paleomagnetic dating, in Quaternary Geochonology:
Methods and Applications, pp. 339–356, eds Noller, J., Sower, J. & Lettis,
W.R., AGU Reference Shelf 4, Washington, D.C.
Vigliotti, L., 2006. Secular variation record of the Earth’s magnetic field in
Italy during the Holocene: constraints for the construction of a master
curve, Geophys. J. Int., 165, 414–429.
Yang, S., Odah, H. & Shaw, J., 2000. Variations in the geomagnetic dipole
moment of the last 12 000 years, Geophys. J. Int., 140, 158–162.
Zijderveld, J.D.A., 1967. A. C. demagnetization of rocks: analysis of results,
in Methods in Palaeomagnetism, pp. 254–286, eds Collinson,D.W., Creer,
K.M. & Runcorn, S.K., Elsevier, Amsterdam.