CGRG Bibliography of Canadian Geomorphology
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Author : Barletta, F.; and St-Onge, G.
Date : 2006.
Title : High resolution Holocene magnetic stratigraphy of the Beaufort Sea: Preliminary results.
Publication : Joint Annual Meeting of the Geological Association of Canada and the Mineralogical Association of Canada. University of Quebec in Montreal (UQAM) May 14-17, 2006.
Issue :
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Abstract
Six long Holocene piston cores were raised in the summer 2004 on board the icebreaker CCGS Amundsen in the Mackenzie Shelf or Gulf of Amundsen as part of the Canadian Arctic Shelf Exchange Study (CASES) in order to study Holocene climatic variability in the Western Canadian Arctic. Cores 650, 711, 750, 803 were collected in the Mackenzie Shelf, while cores 124 and 250 were collected in the Amundsen Gulf. All cores were targeted using multibeam bathymetric and seismic profiles indicating high sediment accumulation areas not influenced by iceberg calving and/or turbidites. In this study, we will present preliminary paleomagnetic data in order to investigate the potential of using past changes in Earth’s magnetic field intensity and direction to develop a regional magnetic stratigraphy. The natural remanent magnetization (NRM) was studied by progressive alternating field (AF) demagnetization of u-channel samples. Representative vector end-point diagrams indicate that each core is characterized by a strong (»10-2A/m) and stable single component magnetization, with maximum angular deviation values (MAD) generally less than 5°. The component paleomagnetic inclinations vary close to the expected inclination (»80°) for the latitude of each core site based on a geocentric axial dipole (GAD) model. In addition, concentration dependent parameters such as low field volumetric magnetic susceptibility, anhysteretic remanent magnetization (ARM) and isothermal remanent magnetization (IRM) vary by less that one order of magnitude, whereas IRM0.3T/IRM1T are close to 1. These data are consistent with dominant low coercivity ferrimagnetic minerals (most likely magnetite), suggesting that these sediments may have preserved a coherent paleomagnetic signal. Indeed, similar component inclination fluctuations characterize all cores, although differences in amplitude are observed, whereas the normalized remanence record (NRM30mT /ARM30mT), a paleointensity proxy, of cores 803, 250 and 650 are similar both in terms of fluctuation and amplitude. These preliminary observations highlight the potential of the paleomagnetic data to correlate the cores together in order to establish a robust regional stratigraphy
Bibliography of Canadian Geomorphology