PP009-0009
Early Holocene Sea Level: New constraints from Submerged Peat Layers in the New York Bight
Tuesday, 8 December 2020
Poster
Peter Brody, Columbia University of New York City, Palisades, NY, United States, Liliette Quintana, Barnard College, New York, NY, United States, Clara Chang, Columbia University of New York, Earth and Environmental Science, NY, NY, United States, Roger Creel, Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY, United States, Jacqueline Austermann, Lamont -Doherty Earth Observatory, Columbia University, Department of Earth and Environmental Sciences, Palisades, NY, United States, Jonathan E Nichols, LDEO-Biology & Paleoenvironment, Palisades, NY, United States, Linda E Heusser, Lamont -Doherty Earth Observatory, Palisades, NY, United States and Dorothy M Peteet, NASA Goddard Institute for Space Studies, New York, NY, United States
Abstract:
The US East Coast continues to respond to the collapse of the Laurentide ice sheet since the last glacial maximum due to the long-term effects of glacial isostatic adjustment (GIA). Glacial isostatic adjustment describes the gravitational, rotational, and deformational responses of the solid earth to loading. Sea level index points along the East Coast such as buried peat layers provide a detailed record of the relative sea level (RSL) changes associated with these responses. Buried peat layers are valuable RSL indicators because they can constrain the age and extent of land that deglacial sea-level rise submerged.
Such peat layers are found in sediment cores collected by the Bureau of Ocean and Energy Management approximately 15 km off the coast of Long Island in the Atlantic Ocean. Preliminary results identify large peat layers in at least 4 cores. The peat layers are typically over- and underlain by sandy-clay deposits typical of marine coastal environments. Previous bulk radiocarbon measurements date these peat layers to between 5000 and 8000 years old. In this study, we use GIS mapping to estimate the extent, thickness and depth of the peat layers and match these data with existing data from seismic surveys. This work is complimented by sedimentological analysis (loss on ignition and grain size analysis), macrofossil and pollen analysis, and macrofossil AMS radiocarbon dating. We assign these data rigorous uncertainty estimates and compare them to an ensemble of deglacial GIA models with a range of solid earth structures and ice histories. Our results place new constraints on US East Coast sea level change during the early Holocene, an interval for which few records exist in this region.
