The Iceland Basin excursion; age, duration, and excursion field geometry

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doi: 10.1002/2014GC005564
Author(s): Channell, J. E. T.
Author Affiliation(s): Primary:
University of Florida, Department of Geological Sciences, Gainesville, FL, United States
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 15(12), p.4920-4935. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 61 refs.; illus., incl. 1 table, sketch map
Summary: The Iceland Basin geomagnetic excursion coincided with the marine isotope stage (MIS) 6/7 boundary. The age and duration of the excursion, at seven North Atlantic sites with sufficient isotope data, are estimated by matching marine isotope stage (MIS) 7a-7c to a calibrated template. Two criteria for defining the excursion, virtual geomagnetic pole (VGP) latitudes <0° and <40°N, yield excursion durations of 1-4 and 2-5 kyr, respectively. The midpoints of the excursion are in the 189-192 ka range, with a mean of ∼190.2 ka. Although component magnetization directions are generally well defined, rapid changes in field direction during a time of low field intensity are not adequately recorded. During the excursion, VGPs transit southward over Africa and the South Atlantic, reach high southern latitudes at the culmination of the excursion, with partial recovery in relative paleointensity (RPI), and then track northward through the western Pacific. The high southern latitude VGPs, and the recovery in RPI, imply that the Earth's main axial dipole reversed polarity during the excursion, if only for ∼1 kyr; implying that excursions can be manifested globally and are important in millennial-scale stratigraphy. VGP clustering in the South Atlantic and NW Pacific roughly coincide with maxima in the vertical-downward component of the modern nondipole (ND) field determined at the Earth's surface, which implies that the ND field became dominant as the geocentric dipole field weakened during the excursion, and also that the ND field configuration is long-lived on multimillennial timescales. Abstract Copyright (2014), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; Africa; Atlantic Ocean; Bermuda Rise; Dipole moment; Expedition 303; Expeditions 303/306; IODP Site U1302; Iceland Basin; Integrated Ocean Drilling Program; Labrador Sea; Leg 162; Leg 172; Magnetic excursions; Magnetic intensity; North Atlantic; Northwest Atlantic; ODP Site 1063; ODP Site 980; ODP Site 983; ODP Site 984; Ocean Drilling Program; Ocean floors; Pacific Ocean; Paleomagnetism; Pole positions; Reykjanes Ridge; Rockall Bank; South Atlantic; West Pacific
Coordinates: N500000 N650000 W0400000 W0650000
Record ID: 2016077714
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom, Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union