The Holocene paleosecular variation record from Elk Lake, Minnesota

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Abstract
The paleosecular variation record of the geomagnetic field from Elk Lake, Minnesota, is presented and its implications are discussed. The Elk Lake record is compiled from measurements of four parallel cores with a 2 cm sampling interval (≈15 years). Time control is provided by radiocarbon dates and by annual laminations (varves) in the sediment. Stratigraphic control is provided by the annual laminations and by fine scale (2–5 cm) variations in magnetic susceptibility. The varve chronology provides improved time control for the central North American paleosecular variation record back to about 4000 years. The results of this study largely confirm the results of Lund and Banerjee from Lake St. Croix and Kylen Lake and demonstrate the general utility of Holocene sediment paleomagnetic records. Differences between the records appear to be due to experimental procedure so minimal procedures are recommended for future work. Comparison of North American and European records suggests that two drifting, non‐dipole sources, one having its advent during the last 5000 years, can account for much of the secular variation.