Document Type

Article

Publication Date

2008

Department

Environmental Studies

Abstract

Holocene changes in terrestrial provenance and processes of sediment transport and deposition are tracked along a fjord-to-shelf transect adjacent to Vestfirdir, Iceland, using the magnetic properties ofmarine sediments.Magnetic susceptibility (MS) profiles of 10 cores (gravity and piston) were obtained onboard using a Bartington MS loop. Remanent magnetizations were measured at 1-cm intervals from u-channel samples taken from six cores on a cryogenic magnetometer. Between six and nine alternating field demagnetization steps were used to isolate the characteristic magnetization directions. The chronologies of the cores used in this study were determined from AMS14 C dates on mollusks and foraminifera and contrained by the regional occurrance ofthe 10,200 6 60 cal yr. BP Saksunavatn tepha. Correlative fluctuations in magneticconcentration are noted between the fjord and shelf sites, though these fluctuations are partiallymasked by regional variations in carbonate content. The onset of Neoglaciation is interpreted by changes in magnetic properties including an increase in mass magneticsusceptibility that began approximately 3000 cal yr. BP. The maximum angular deviation and the median destructive field (generally 20 mT) suggest that the natural remanent magnetization is carried by a coarse ferrimagnetite mineralogy, likely magnetite or titano-magnetite. Reproducible paleomagnetic inclination values are observed in several records, including a nearly vertical inclination around 8000 cal yr. BP, suggesting that the magnetic pole may have been proximal to Iceland, followed by an interval of much shallower inclination (6000–7000 cal yr. BP).

Required Publisher's Statement

This article is posted here by permission of the University of Colorado at Boulder for personal use, not redistribution.This article was published in Artic, Antartic, and Alpine Research, Volume 20, Number 1, 2008. DOI: 10.1657/1523-0430(05-072)[ANDREWS]2.0.CO;2.

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