Sediment Cores From White Pond, South Carolina, Contain a Platinum Anomaly, Pyrogenic Carbon Peak, and Coprophilous Spore Decline at 12.8 Ka

Abstract

A widespread platinum (Pt) anomaly was recently documented in Greenland ice and 11 North American sedimentary sequences at the onset of the Younger Dryas (YD) event (~12,800 cal yr BP), consistent with the YD Impact Hypothesis. We report high-resolution analyses of a 1-meter section of a lake core from White Pond, South Carolina, USA. After developing a Bayesian age-depth model that brackets the late Pleistocene through early Holocene, we analyzed and quantified the following: (1) Pt and palladium (Pd) abundance, (2) geochemistry of 58 elements, (3) coprophilous spores, (4) sedimentary organic matter (OC and sedaDNA), (5) stable isotopes of C (δ 13 c) and n (δ 15 N), (6) soot, (7) aciniform carbon, (8) cryptotephra, (9) mercury (Hg), and (10) magnetic susceptibility. We identified large Pt and Pt/Pd anomalies within a 2-cm section dated to the YD onset (12,785 ± 58 cal yr BP). These anomalies precede a decline in coprophilous spores and correlate with an abrupt peak in soot and C/OC ratios, indicative of large-scale regional biomass burning. We also observed a relatively large excursion in δ 15 n values, indicating rapid climatic and environmental/hydrological changes at the YD onset. Our results are consistent with the YD Impact Hypothesis and impact-related environmental and ecological changes. Study of late Quaternary climates and their effect on vegetation dynamics of southeastern North America has been hampered by the limited number of radiocarbon-dated pollen sequences extending from the Last Glacial Maximum (LGM) through the Holocene transition. Early paleoenvironmental reconstructions by Watts 1 established White Pond in South Carolina as one of the oldest and most complete paleoenvironmental records in southeastern North America, with a basal core date of at least 22,000 calendar years BP. Watts 1 report on the Pleistocene-Holocene transition at White Pond has served as a benchmark study of paleoclimates and