Holocene Paleomagnetic Secular Variation: What Relationships Between Mid and Polar Latitudes tell us About Geomagnetic Dynamics

English Abstract:

Longitudinal comparisons of high quality, high resolution, and independently dated archeomagnetic and paleomagnetic secular variation (PSV) records from the NE Pacific (Alaska & Hawaii), North America, North Atlantic, and Europe during the Holocene show generally coherent multi-centennial to millennial scale variations of specific PSV parameters. These observations illuminate two primary alternating modes (although there are likely others), which we have called the European mode (EM) and North American mode (NAM) because of their consistency with the late Holocene and historical time average field morphologies, respectively. Here we further explore how alternations between these modes compare with observations made at locations sensitive to the geomagnetic field derived from the Arctic tangent cylinder. High resolution paleomagnetic records obtained from a series of cores retrieved from two Ellesmere Island lakes (Sawtooth Lake, 79º21 N, 83º56 W and Lower Murray Lake, 81°34 N, 69°54 W) with varve based chronologies allow us to define regional PSV and paleointensity (PI) patterns for the last ~5 kyr. Although PSV and PI derived at these polar latitudes are both distinct from those observed at mid latitudes and prediction made from global field models, consistencies in timing suggest that these records are dynamically related. This duality is illustrated by variations in virtual geomagnetic pole (VGP) latitude, where those derived from polar latitude sites are both in phase and out of phase with those derived from mid latitude sites and global reconstructions. Axial VGP latitudes are observed during EM and NAM maximums, whereas mid latitude and global reconstructions show axial VGPs during NAM and maximum tilt during EM. It is also illustrated by patterns of PI where repeating progression of PI highs and lows are observed mid and polar latitudes. Together these define coherent oscillations showing that geomagnetic behavior in the tangent cylinder is distinct from, but influenced by, large scale oscillations in flux observed at mid latitudes.