A PRELIMINARY PALEOMAGNETIC STUDY OF THE GLACIAL LACUSTRINE/CHAMPLAIN SEA TRANSITION IN CORES FROM THE NORTHERN LAKE CHAMPLAIN VALLEY, NEW YORK
A pilot paleomagnetic study was conducted on a 150-cm long u-channel sample collected from the center of a split core containing the upper glacial lacustrine and transitional sediments. We estimate this to represent a duration of less than 200 years. The u-channel sample was subjected to stepwise alternating field demagnetization at a 1-cm measurement interval using an automated long-core cryogenic magnetometer. The sediments exhibited a strong and stable magnetization with magnetite as the predominant magnetic carrier. Although the coring was done with a vibra-corer, the paleomagnetic directions were coherent and did not show significant changes over the length of the u-channel, which is consistent with the estimated short duration. The mean inclination of about 48 degrees is also consistent with published results from contemporaneous varve sections in the region. Because the core was not azimuthally oriented, absolute declination values could not be determined. These results indicate that paleomagnetic studies of longer cored intervals can provide records of paleosecular variation that can be used for correlation and dating of these sediments.