Holocene Full-Vector Secular Variation from African Lakes

Friday, 19 December 2014: 9:00 AM
Steven Lund1, Ellen S Platzman1, Thomas C Johnson2, Christopher A Scholz3, Andrew S Cohen4 and James M Russell5, (1)University of Southern California, Los Angeles, CA, United States, (2)University of Minnesota Duluth, Duluth, MN, United States, (3)Syracuse University, Syracuse, NY, United States, (4)University of Arizona, Department of Geosciences, Tucson, AZ, United States, (5)Brown University, Providence, RI, United States
We are developing a regional pattern of Holocene paleomagnetic secular variation (PSV) from four lakes in East Africa – Lake Turkana (3°N), Lake Victoria (1°S), Lake Tanganyika (5°S), and Lake Malawi (10°S). Detailed paleomagnetic and rock magnetic measurements have been made on two cores from Lake Malawi (9m meters in depth, last ~10,000 years), two cores from Lake Victoria (8 m, last ~8,000 years), 11 cores from Lake Turkana (2-9 m, last ~10,000 years), and one core from Lake Tanganyika (5 m, last ~5,000 years). Our rock magnetic studies identify significant intervals of magnetic mineral dissolution in Lakes Victoria and Tanganyika making parts of these cores unsuitable for relative paleointensity studies. On the other hand, rock magnetic variability in the Lake Malawi and Lake Turkana cores are stable and correlatable among cores. We have recovered directional secular variation records from Lakes Malawi, Victoria, and Turkana. Millennial-scale inclination and declination features can be correlated among cores at each lake and between lakes. We have also recovered relative paleointensity records from Lakes Malawi and Turkana. More than 20 radiocarbon dates and detailed seismic stratigraphy (Turkana) provide critical added information for correlating and dating the paleomagnetic records.