210Pb Geochronology

Khadijah Karrington Homolka, Earth and Space Sciences & Oceanography

With the rate of temperature rise on the Western Antarctic Peninsula (WAP) being six times higher than the global average, the effects of modern climate change on glacier dynamics and meltwater production hold particular significance for sediment accumulation rates. Little data exists for examining the subbasin variability of sediment accumulation in an individual fjord, where only 1-2 cores per fjord are available. In Andvord Bay, Antarctica, modern sediment accumulation rates were determined from 10 kasten cores, and 4 box cores collected throughout the fjord aboard the R/V Nathaniel B. Palmer. A relatively low circulation velocity, and numerous deep basins throughout the fjord created ideal conditions for sediment to accumulate, and to be easily cored. Sediment accumulation rates were determined using 210Pb geochronology, where excess 210Pb activity profiles reveal spatially variable sediment accumulation rates throughout the fjord that are on the order of millimeters of accumulation per year. These modern accumulation rates agree with previously determined accumulation rates in polar and subpolar fjords, and are significantly slower than those of temperate tidewater glaciers. These excess 210Pb activity profiles provide further insight into the small-scale spatial variability of sediment transport and accumulation in individual fjords, and contribute to the subpolar-polar sediment accumulation dataset that is imperative for understanding the effects of modern climate change on the dynamics of glaciers at polar latitudes.