Geomagnetic Excursions and High-Latitude Paleomagnetic Records of Glaciomarine Sediments from the Western Greenland Margin (Baffin Bay)
Abstract
We present new paleomagnetic results from Quaternary sediment samples recovered during the Baffin Bay Scientific Coring Expedition conducted by the JOIDES Resolution in 2012. The expedition recovered well-preserved core material from the Arctic Basin, providing an outstanding opportunity for the study of the behavior of the geomagnetic field at high latitude. We analyzed material from 12 sites cored at latitudes between 74°45.32'N and 75°46.68'N in the Melville Bay region (Cape York and Melville Ridge) of Baffin Bay located at an average water depth of 394 m. The Quaternary glaciomarine sediments are up to 150 m thick and consist of very soft diatom-bearing muds to clast-rich sandy and muddy diamicts, which suggest deposition in a subglacial to ice-procimal environment. We carried out paleomagnetic and rock magnetic measurements on the shipboard cryogenic magnetometer at 5-cm resolution on 32 split-core sections and a selected number of discrete samples, and recently processed measurements taken at 1-cm resolution on eight U-channel samples from the uppermost Holocene part of the section. Stepwise demagnetization of the NRM demonstrates excellent demagnetization behavior, with a viscous isothermal remanent magnetization overprint, induced by the coring and sampling process, and typically removed by the 20 mT demagnetization step. The magnetic inclination data are characterized by steep, 80°, normal inclinations, consistent with the site position near the North Pole. Thermal demagnetization, magnetic susceptibility, isothermal remanent magnetization, and hysteresis parameters indicate that the primary magnetic carrier consists of a low-coercivity mineral, e.g., magnetite and/or titanomagnetite, with minor traces of higher-coercivity minerals. Well-developed geomagnetic excursions in the upper part of the section can be correlated between several sites. Although dating of these sediments remains a challenge because of the lack of carbonates we will discuss possible age models and use them to assign ages to the geomagnetic excursions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMGP33B0977R
- Keywords:
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- 1513 Geomagnetic excursions;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1521 Paleointensity;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1535 Reversals: process;
- timescale;
- magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1560 Time variations: secular and longer;
- GEOMAGNETISM AND PALEOMAGNETISM