XRF ANALYSIS OF GLACIAL LAKE WARRENSBURG SEDIMENT CORES: CLIMATIC AND GEOLOGIC CONTROLS ON VARVE GEOCHEMISTRY

Geochemical analysis of glacial lake sediments reveals properties useful for understanding characteristics of paleoclimate during retreat. Varve samples deposited in ancient Glacial Lake Warrensburg created during the retreat of the Laurentide Ice Sheet in the Hudson River valley in Warrensburg, NY north of Lake Luzerne were collected and studied. Glacial Lake Warrensburg varves were most likely deposited during the Bolling/Allerod warm period between the Luzerne Readvance and the Bridgeport/Middlesex Readvance, around 12.6 -11.9 ka. In this follow-up to a 2012 pilot study, cores were collected from the top and bottom of a >15 meter thick exposure of varves . Cores from the previous study were retrieved from the middle of this varve outcrop. The chronology of the varves was determined by counting the layers as presented at this meeting in Khan et al’s poster. Split and prepared core surfaces were subjected to Handheld X-Ray Fluorescent (XRF) Spectrometer geochemical analysis to measure downcore trends of trace elements Si, K, Ca, Ti, and Fe. For each core, XRF measurements were taken at 8mm intervals along the entire core. The two new varve cores presented here are compared with the two cores from Ancient Glacial Lake Warrensburg studied and collected previously. Significant geochemical variations from the new cores, and their climate proxy interpretations will be presented. This study contributes further insight into the conditions of the New York region during post-glacial retreat of the Laurentide Ice Sheet in the Hudson Valley. In this study, we identify climate and geological factors controlling the geochemistry of varves deposited in Glacial Lake Warrensburg, contribute new descriptions to the paleoclimate depositional characteristics of the site, and open up future work for continued study of the geochemistry of glacial varve deposits in the northern Hudson Valley.