Geomagnetic record in Minnesota lake sediments—Absence of the Gothenburg and Erieau excursions

Abstract

Several excursions of the geomagnetic field during the Brunhes epoch have been postulated on the basis of paleomagnetic data from sediments. It has further been suggested that these excursions may represent sudden fluctuations of the geomagnetic field, manifested especially in fluctuations of the local geomagnetic inclination. In this study we present high-resolution data of inclination variations recorded in the sediments of two Minnesota postglacial lakes. To the best of our knowledge, our data cover two overlapping time windows, 0 to 9600 B.P. and about 9000 to 16,000 B.P. The results strongly suggest that no excursions have occurred in Minnesota over the past 16,000 yr. Thus, it appears that the Gothenburg (Sweden) excursion at about 12,500 B.P. is not worldwide and that the regional Erieau (Lake Erie) excursion does not extend to Minnesota. We suggest that these two previously claimed excursions might not reflect geomagnetic field behavior but merely poor paleomagnetic “recording” within the sediments used for these studies.