Holocene Southern Atlantic Earth's Magnetic Field Variations

Monika C Korte1, Ute Frank2, Norbert R Nowaczyk3, Thomas Frederichs4 and Maxwell Christopher Brown3, (1)Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Section 2.3 – Geomagnetism, Potsdam, Germany, (2)Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Section 4.3 – Paleoclimate and Landscape evolution, Potsdam, Germany, (3)Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, (4)University of Bremen, Department of Geosciences, Bremen, Germany

Contact First Author: Monika C Korte; monika@gfz-potsdam.de

Previously Published Material: The new data have been presented at recent AGU and SEDI meetings. First, very preliminary modelling results using all the data have partly been presented at fall AGU 2014.

Abstract ID#: 33778

 

English Abstract:
Sediment records of past Earth's magnetic field resolving variations in the southern hemisphere during the Holocene are sparse to the present day. Spherical harmonic field models provide magnetic field component predictions for the whole globe, but might show too little or even unreliable spurious structure in the regions not constrained sufficiently by data.

We have carried out paleomagnetic investigations of sediment cores from six locations at southern hemisphere and equatorial latitudes to better constrain field variation shown by global models in particular in the southern Atlantic region. Lakes Chamo and Chew Bahir are located in Ethiopia. Marine records ODP 1078 and 1079 lie off the coast of Angola, GeoB6517-2 and ODP 1076D are located in the Congo Fan and M35003-4 is situated southeast of Grenada in the Tobago Basin. In addition to the paleomagnetic work all cores were subjected to a comprehensive set of rock magnetic measurements. Age-depth models based on radiocarbon dating were determined for the Ethiopian sites. For all the marine cores, published age-depth models were available from earlier climatic studies at these sites.

We include the new records in millennial scale global models of the CALSxk type. We discuss magnetic field variations in the southern Atlantic region as shown directly by the data and as described by new and previous models. We conclude that robust variation structures are emerging but some characteristics of records and models require further investigation. Even more new data are important to improve the reliability of global models regarding southern hemisphere field variations.

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