In collaboration with my old friend and colleague Dr. Les Hasbargen (SUNY Oneonta) I have been collecting samples and data from Otsego lake in Upstate New York. After two field seasons we have collected several sediment cores and have conducted a dozen ground-penetrating-radar (GPR) surveys. Some of our cores are dated, and the dateable sediment record covers approximately 9,000 years. Our cores consist of carbonate-rich (marl) sediments with plenty of shells and some plant fossils which had been deposited on top of clastic, partially varved silt and clay.
We are currently characterizing the magnetic properties of the weakly magnetized marl section. Concentration-dependent susceptibility and IRM correlate well with the abundance of clastic material (as quantified through X-ray diffraction, XRD), while grain-size dependent parameters, such as frequency-dependent susceptibility χ FD % and ARM/IRM track the abundance of (likely) biogenic magnetite and may be a proxy of biological productivity through time.