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Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/3013

Authors: Jovane, L.*
Florindo, F.*
Acton, G.*
Verosub, K. L.*
Title: Geomagnetic Field Behavior at High Latitudes from a Paleomagnetic Record from Eltanin Core 27-21 in the Ross Sea Sector, Antarctica
Issue Date: 2007
DOI: 10.1016/j.epsl.2007.12.006
Keywords: Antarctica
Eltanin
tangent cylinder
geomagnetism
paleomagnetism
magnetostratigraphy
Ross Sea
geodynamo
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 meters 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 (0-0.78 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 69.6° latitude, which is very close to the latitude of Eltanin 27-21.
Appears in Collections:Manuscripts
04.05.02. Geomagnetic field variations and reversals

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