T11 Environmental Magnetism, Magnetic Stratigraphy, and Magnetic Field Modeling

Sunday, 18 October 2009
8:00 AM - 12:00 PM
Portland Ballrooms 251/258

RECONSTRUCTING HOLOCENE PALEOMAGNETIC SECULAR VARIATION FROM NORTH ATLANTIC DEEP-SEA SEDIMENT

Paper number: T11-5
Program: Technical Sessions
Time: 9:10 AM – 9:25 AM

Authors

Abstract

North Atlantic paleomagnetic records have been instrumental in the development of modern paleomagnetic concepts that show a highly variable field even during times of constant polarity. Most recent paleomagnetic studies have focused on relative paleointensity (RPI) in the Pleistocene, yet the detailed dynamics of the full magnetic vector are under-explored. Here we present a set of 5 high-resolution (~15-35 cm/kyr) North Atlantic deep-sea sediment paleomagnetic records that capture Holocene paleomagnetic secular variation (PSV) and RPI. All of these records span at least the past 8000 years with centennial-scale resolution. Two of the cores, KN-158-4-2 (43°29′N, 54°52′W, 3942 m) and KN-158-4-22 (44°18′N, 46°15′W, 3959 m) are from the Northwestern Atlantic, on the continental rise and south of the St. Lawrence Estuary where ultra-high resolution PSV and RPI records exist. These two cores record internally consistent PSV, but low Holocene RPI variability. Conversely, cores from the Northeast Atlantic, KN-158-4-53 (55°27′N, 14°42′W, 2184 m), KN-158-4-57 (58°39′N, 25°25′W, 2768 m) and KN-158-4-46 (52°58′N, 19°49′W, 2758 m) show notable temporal and spatial variations in Holocene RPI and PSV consistent with ultra-high resolution PSV records from the Iceland and Greenland Margins. Whether these differences reflect the true geomagnetic or sedimentary artifacts is presently unknown and will be explored in this presentation.

Implications are important for understanding the dynamics of the geomagnetic field. Further study of the differences in these 2 sets of cores will enhance our understanding of geomagnetic flux lobes and geodynamo effects on sedimentary recording of PSV. These records will improve our ability to determine PSV and RPI from sediment cores by examining each core’s correlation with MD99-2269 from the Labrador Sea (Stoner et al., 2006), which represents the best archive we have of high-resolution North Atlantic PSV and RPI. This study will enhance our ability to find sites with useful records from the North Atlantic, improving our understanding of the unique perspective of the geomagnetic field, recorded in the North Atlantic as well as our ability to use North Atlantic sediment cores to understand Holocene PSV.