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Geomagnetic field behavior at high latitudes from a paleomagnetic record from Eltanin core 27–21 in the Ross Sea sector, Antarctica
Author(s)
Language
English
Obiettivo Specifico
2.2. Laboratorio di paleomagnetismo
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
/ 267 (2008)
Publisher
Elsevier
Pages (printed)
435-443
Issued date
2008
Alternative Location
Abstract
We present a high-resolution paleomagnetic record from 682 discrete samples from Eltanin 27–21 (69.03°S 179.83°E), a 16-meter long piston core recovered in 1968 at a water depth of 3456 m by the USNS Eltanin as part of Operation Deep Freeze. After removal of a low-coercivity overprint, most samples yield stable characteristic remanent magnetization directions. The downhole variation in the magnetic inclination provides a well-resolved magnetostratigraphy from the Brunhes Chron (0–0.781 Ma), through the Reunion Subchron (2.128–2.148 Ma), and into Chron C2r.2r. The sedimentation rates are sufficiently high that even short-term geomagnetic features, like the Cobb Mountain excursion, are resolved.
The record from Eltanin 27–21 provides new insights into the behavior of the geomagnetic field at high latitudes, about which very little is currently known. Using the variability in the inclinations during stable polarity intervals, we estimate that the dispersion in the paleomagnetic pole position over the past ~2 Myr is 30.3°±4.3°, which is significantly greater than observed at low to mid latitude sites. The higher dispersion
observed at Eltanin 27–21 is consistent with numerical modeling of the geodynamo. That modeling has shown that polar vortices can develop in the Earth's core within the tangent cylinder, defined as the cylinder coaxial with the Earth's rotation axis and tangent to the inner core/outer core boundary. The polar vortices produce vigorous fluid motion in the core, which creates greater geomagnetic field variability above the tangent cylinder at the surface of the Earth. The tangent cylinder intersects the Earth's surface in the polar regions at 79.1° latitude, which is relatively close to the latitude of Eltanin 27–21.
The record from Eltanin 27–21 provides new insights into the behavior of the geomagnetic field at high latitudes, about which very little is currently known. Using the variability in the inclinations during stable polarity intervals, we estimate that the dispersion in the paleomagnetic pole position over the past ~2 Myr is 30.3°±4.3°, which is significantly greater than observed at low to mid latitude sites. The higher dispersion
observed at Eltanin 27–21 is consistent with numerical modeling of the geodynamo. That modeling has shown that polar vortices can develop in the Earth's core within the tangent cylinder, defined as the cylinder coaxial with the Earth's rotation axis and tangent to the inner core/outer core boundary. The polar vortices produce vigorous fluid motion in the core, which creates greater geomagnetic field variability above the tangent cylinder at the surface of the Earth. The tangent cylinder intersects the Earth's surface in the polar regions at 79.1° latitude, which is relatively close to the latitude of Eltanin 27–21.
References
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sediment drifts on the continental rise of West Antarctica (ODP Leg 178,
Sites 1095, 1096, and 1101). In: Barker, P.F., Camerlenghi, A., Acton, G.D.,
Ramsay, A.T.S. (Eds.), Proceedings of the Ocean Drilling Program.
Scientific Results, vol. 178. Ocean Drilling Program, College Station,
Texas, p. 1000.
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Arason, P., Levi, S., 2006b, The maximum likelihood solution for inclinationonly
data, unpublished report downloaded 21 June 2007 from http://andvari.
vedur.is/~arason/paleomag/.
Aurnou, J.M.,Andreadis, S., Zhu, L.,Olson, P.L., 2003. Experiments on convection
in Earth's core tangent cylinder. Earth Planet. Sci. Lett. 212, 119–134.
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Deception Island, South Shetland Islands, Antarctica. Geophys. J. Int. 153,
333–343.
Bloxham, J., Jackson, A., 1992. Time-dependent mapping of the magnetic field
at the core–mantle boundary. J. Geophys. Res. 97, 19537–19563.
Cox, A., 1969. Confidence limits for the precision parameter κ. Geophys. J. R.
Astron. Soc. 18, 545–549.
Cox, A., Gordon, R.G., 1984. Paleolatitudes determined from paleomagnetic
data from vertical cores. Rev. Geophys. Space Phys. 22, 47–72.
Fillon, R.H., 1975. Late Cenozoic paleo-oceanography of Ross Sea, Antarctica.
Bull. Geol. Soc. Am. 86, 839–845.
Glatzmaier, G.A., Roberts, P.H., 1995. A three-dimensional convective dynamo
solution with rotating and finitely conducting inner core and mantle. Phys.
Earth Planet. Inter. 91, 63–75.
Goodell, H.G., 1968. USNS Eltanin Cruises 16–27, core descriptions:
sedimentology research Laboratory Contribution, n. 25, Department of
Geology, Florida State University, Tallahassee, 247 p., http://www.arf.fsu.
edu/publications/ELT_16_27.pdf.
Gradstein, F.M., Ogg, J.G., Smith, A.G., 2004. A Geological Time Scale 2004.
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Gubbins, D., Bloxham, J., 1985. Geomagnetic field analysis — III. Magnetic
fields on the core–mantle boundary. Geophys. J. R. Astron. Soc. 80, 695–713.
Gubbins, D., Bloxham, J., 1987. Morphology of the geomagnetic field and
implications for the geodynamo. Nature 325, 509–511.
Gubbins, D., Jones, A.L., Finlay, C.C., 2006. Fall in Earth's magnetic field is
erratic. Science 312, 900–902.
Hartl, P., Tauxe, L., 1996. A precursor to the Matuyama/Brunhes transition-field
instability as recorded in pelagic sediments. Earth Planet. Sci. Lett. 138,
121–135.
Hulot, G., Eymin, C., Langlais, B., Mandea, M., Olsen, N., 2002. Small-scale
structure of the geodynamo inferred from Oersted and Magsat satellite data.
Nature 416, 620–623.
Jackson, A., Jonkers, A.R.T., Walker, M.R., 2000. Four centuries of
geomagnetic secular variation from historical records. Phil. Trans. R. Soc.
London Ser. A 358, 957–990.
Kennett, J.P., 1977. Cenozoic evolution of Antarctic glaciation, the Circum–
Antarctic Ocean, and their impact on global paleoceanography. J. Geophys.
Res. 82, 3843–3860.
Kirschvink, J.L., 1980. The least-squares line and plane and the analysis of
paleomagnetic data. Geophys. J. R. Astron. Soc. 62, 699–718.
Kodama, K.P., 1997. A successful rock magnetic technique for correcting
paleomagnetic inclination shallowing: case study of the Nacimiento
Formation, New Mexico. J. Geophys. Res. 102, 5193–5205.
Kuang,W., Bloxham, J., 1997. An Earth-like numerical dynamo model. Nature 389,
371–374.
McFadden, P.L., Reid, A.B., 1982. Analysis of palaeomagnetic inclination data.
Geophys. J. R. Astron. Soc. 69, 307–319.
Nowaczyk, N.R., Knies, J., 2000. Magnetostratigraphic results from eastern
Arctic Ocean-AMS 14C ages and relative paleointensity data of the Mono
Lake and Laschamp geomagnetic reversal excursions. Geophys. J. Int. 140,
185–197.
Nowaczyk, N.R., Frederichs, T.W., Eisenhauer, A., Gard, G., 1994. Magnetostratigraphic
data from late Quaternary sediments from the Yermak Plateau,
Arctic Ocean: evidence for four geomagnetic polarity events within the last
170 Ka of the Brunhes Chron. Geophys. J. Int. 117, 453–471.
Nowaczyk, N.R., Frederichs, T.W., Kassens, H., Norgaard-Pedersen, N.,
Spielhagen, R.F., Stein, R., Weiel, D., 2001. Sedimentation rates in the
Makarov Basin, central Artic Ocean: A paleomagnetic and rock magnetic
approach. Paleoceanography 16, 368–389.
Olson, P., Aurnou, P., 1999. A polar vortex in the Earth's core. Nature 402,
170–173.
Olson, P., Sumita, I., Aurnou, J., 2002. Diffusive magnetic images of upwelling
patterns in the core. Geophys. J. Int. 107, 2348. doi:10.1029/2001JB000384.
Quidelleur, X., Courtillot, V., 1996. On low-degree spherical harmonic models
of paleosecular variation. Phys. Earth Planet. Inter. 95, 55–77.
Quidelleur, X., Valet, J.-P., Courtillot, V., Hulot, G., 1994. Long-term geometry
of the geomagnetic field for the last five million years; an updated secular
variation database. Geophys. Res. Lett. 21, 1639–1642.
Singer, B.S., Relle, M.K., Hoffman, K.A., Battle, A., Laj, C., Guillou, H.,
Carracedo, J.C., 2002. Ar/Ar ages from transitionally magnetized lavas on
La Palma, Canary Islands, and the geomagnetic instability timescale.
J. Geophys. Res. 107, 2307. doi:10.1029/2001JB001613.
Spielhagen, R.F., Baumann, K.-H., Erlenkeuser, H., Nowaczyk, N.R., Norgaard-
Pedersen, N., Vogt, C., Weiel, D., 2004. Arctic Ocean deep-sea record of
northern Eurasian ice sheet history. Quat. Sci. Rev. 23, 1455–1483.
Tauxe, L., 2005. Inclination flattening and the geocentric axial dipole
hypothesis. Earth Planet. Sci. Lett. 233, 247–261.
Tauxe, L., Gans, P., Mankinen, E.A., 2004. Paleomagnetism and Ar-40/Ar-39
ages from volcanics extruded during the Matuyama and Brunhes Chrons
near McMurdo Sound, Antarctica. Geochem. Geophys. Geosys. 5, Q06H12.
Wardinski, I., Holme, R., 2006. A time-dependent model of the Earth's magnetic
field and its secular variation for the period 1980–2000. J. Geophys. Res. 111,
B12101. doi:10.1029/2006JB004401.
Watkins, N.D., Kennett, J.P., 1972. Regional sedimentary disconformities and
upper Cenozoic changes in bottom water velocity between Australia and
Antarctica. In: Hayes, D.E. (Ed.), Antarctic Oceanology II, The Australian–
New Zealand Sector. Antartic Res. Ser., vol.19, pp. 273–294.
sediment drifts on the continental rise of West Antarctica (ODP Leg 178,
Sites 1095, 1096, and 1101). In: Barker, P.F., Camerlenghi, A., Acton, G.D.,
Ramsay, A.T.S. (Eds.), Proceedings of the Ocean Drilling Program.
Scientific Results, vol. 178. Ocean Drilling Program, College Station,
Texas, p. 1000.
Arason, P., Levi, S., 2006a. The maximum likelihood solution to inclinationonly
data. Eos Trans. AGU 86 (62), GP21B–GP1312 Fall Meet. Abstract.
Arason, P., Levi, S., 2006b, The maximum likelihood solution for inclinationonly
data, unpublished report downloaded 21 June 2007 from http://andvari.
vedur.is/~arason/paleomag/.
Aurnou, J.M.,Andreadis, S., Zhu, L.,Olson, P.L., 2003. Experiments on convection
in Earth's core tangent cylinder. Earth Planet. Sci. Lett. 212, 119–134.
Baraldo, A., Rapalini, A.E., Böhnel, H.,Mena1,M., 2003. Paleomagnetic study of
Deception Island, South Shetland Islands, Antarctica. Geophys. J. Int. 153,
333–343.
Bloxham, J., Jackson, A., 1992. Time-dependent mapping of the magnetic field
at the core–mantle boundary. J. Geophys. Res. 97, 19537–19563.
Cox, A., 1969. Confidence limits for the precision parameter κ. Geophys. J. R.
Astron. Soc. 18, 545–549.
Cox, A., Gordon, R.G., 1984. Paleolatitudes determined from paleomagnetic
data from vertical cores. Rev. Geophys. Space Phys. 22, 47–72.
Fillon, R.H., 1975. Late Cenozoic paleo-oceanography of Ross Sea, Antarctica.
Bull. Geol. Soc. Am. 86, 839–845.
Glatzmaier, G.A., Roberts, P.H., 1995. A three-dimensional convective dynamo
solution with rotating and finitely conducting inner core and mantle. Phys.
Earth Planet. Inter. 91, 63–75.
Goodell, H.G., 1968. USNS Eltanin Cruises 16–27, core descriptions:
sedimentology research Laboratory Contribution, n. 25, Department of
Geology, Florida State University, Tallahassee, 247 p., http://www.arf.fsu.
edu/publications/ELT_16_27.pdf.
Gradstein, F.M., Ogg, J.G., Smith, A.G., 2004. A Geological Time Scale 2004.
Cambridge Univ. Press, Cambridge. 589 p.
Gubbins, D., Bloxham, J., 1985. Geomagnetic field analysis — III. Magnetic
fields on the core–mantle boundary. Geophys. J. R. Astron. Soc. 80, 695–713.
Gubbins, D., Bloxham, J., 1987. Morphology of the geomagnetic field and
implications for the geodynamo. Nature 325, 509–511.
Gubbins, D., Jones, A.L., Finlay, C.C., 2006. Fall in Earth's magnetic field is
erratic. Science 312, 900–902.
Hartl, P., Tauxe, L., 1996. A precursor to the Matuyama/Brunhes transition-field
instability as recorded in pelagic sediments. Earth Planet. Sci. Lett. 138,
121–135.
Hulot, G., Eymin, C., Langlais, B., Mandea, M., Olsen, N., 2002. Small-scale
structure of the geodynamo inferred from Oersted and Magsat satellite data.
Nature 416, 620–623.
Jackson, A., Jonkers, A.R.T., Walker, M.R., 2000. Four centuries of
geomagnetic secular variation from historical records. Phil. Trans. R. Soc.
London Ser. A 358, 957–990.
Kennett, J.P., 1977. Cenozoic evolution of Antarctic glaciation, the Circum–
Antarctic Ocean, and their impact on global paleoceanography. J. Geophys.
Res. 82, 3843–3860.
Kirschvink, J.L., 1980. The least-squares line and plane and the analysis of
paleomagnetic data. Geophys. J. R. Astron. Soc. 62, 699–718.
Kodama, K.P., 1997. A successful rock magnetic technique for correcting
paleomagnetic inclination shallowing: case study of the Nacimiento
Formation, New Mexico. J. Geophys. Res. 102, 5193–5205.
Kuang,W., Bloxham, J., 1997. An Earth-like numerical dynamo model. Nature 389,
371–374.
McFadden, P.L., Reid, A.B., 1982. Analysis of palaeomagnetic inclination data.
Geophys. J. R. Astron. Soc. 69, 307–319.
Nowaczyk, N.R., Knies, J., 2000. Magnetostratigraphic results from eastern
Arctic Ocean-AMS 14C ages and relative paleointensity data of the Mono
Lake and Laschamp geomagnetic reversal excursions. Geophys. J. Int. 140,
185–197.
Nowaczyk, N.R., Frederichs, T.W., Eisenhauer, A., Gard, G., 1994. Magnetostratigraphic
data from late Quaternary sediments from the Yermak Plateau,
Arctic Ocean: evidence for four geomagnetic polarity events within the last
170 Ka of the Brunhes Chron. Geophys. J. Int. 117, 453–471.
Nowaczyk, N.R., Frederichs, T.W., Kassens, H., Norgaard-Pedersen, N.,
Spielhagen, R.F., Stein, R., Weiel, D., 2001. Sedimentation rates in the
Makarov Basin, central Artic Ocean: A paleomagnetic and rock magnetic
approach. Paleoceanography 16, 368–389.
Olson, P., Aurnou, P., 1999. A polar vortex in the Earth's core. Nature 402,
170–173.
Olson, P., Sumita, I., Aurnou, J., 2002. Diffusive magnetic images of upwelling
patterns in the core. Geophys. J. Int. 107, 2348. doi:10.1029/2001JB000384.
Quidelleur, X., Courtillot, V., 1996. On low-degree spherical harmonic models
of paleosecular variation. Phys. Earth Planet. Inter. 95, 55–77.
Quidelleur, X., Valet, J.-P., Courtillot, V., Hulot, G., 1994. Long-term geometry
of the geomagnetic field for the last five million years; an updated secular
variation database. Geophys. Res. Lett. 21, 1639–1642.
Singer, B.S., Relle, M.K., Hoffman, K.A., Battle, A., Laj, C., Guillou, H.,
Carracedo, J.C., 2002. Ar/Ar ages from transitionally magnetized lavas on
La Palma, Canary Islands, and the geomagnetic instability timescale.
J. Geophys. Res. 107, 2307. doi:10.1029/2001JB001613.
Spielhagen, R.F., Baumann, K.-H., Erlenkeuser, H., Nowaczyk, N.R., Norgaard-
Pedersen, N., Vogt, C., Weiel, D., 2004. Arctic Ocean deep-sea record of
northern Eurasian ice sheet history. Quat. Sci. Rev. 23, 1455–1483.
Tauxe, L., 2005. Inclination flattening and the geocentric axial dipole
hypothesis. Earth Planet. Sci. Lett. 233, 247–261.
Tauxe, L., Gans, P., Mankinen, E.A., 2004. Paleomagnetism and Ar-40/Ar-39
ages from volcanics extruded during the Matuyama and Brunhes Chrons
near McMurdo Sound, Antarctica. Geochem. Geophys. Geosys. 5, Q06H12.
Wardinski, I., Holme, R., 2006. A time-dependent model of the Earth's magnetic
field and its secular variation for the period 1980–2000. J. Geophys. Res. 111,
B12101. doi:10.1029/2006JB004401.
Watkins, N.D., Kennett, J.P., 1972. Regional sedimentary disconformities and
upper Cenozoic changes in bottom water velocity between Australia and
Antarctica. In: Hayes, D.E. (Ed.), Antarctic Oceanology II, The Australian–
New Zealand Sector. Antartic Res. Ser., vol.19, pp. 273–294.
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