EAPSI: Evaluating the Impact of an Unusual Meteorite at the Onset of Younger Dryas Using a Greenland Ice Core

Seo Ji-Hye, Wilder VT

Investigators

Abstract

The Younger Dryas is a major cooling period from 12,900 to 11,600 years before present subsequent to the last glaciation. The cause of this abrupt cooling is poorly understood. A highly controversial hypothesis suggests that a number of meteorite or comet impacts triggered sudden release of meltwater from proglacial Lake Agassiz (Great Lakes), disrupting oceanic circulation, and eventually leading to long term cooling. Recently, remarkably high Platinum and low Iridium concentrations have been discovered in the Greenland ice core at the onset of Younger Dryas, indicating an unusually Platinum enriched iron meteorite impact. However, another study suggested that these abnormal concentrations could be from weathering of ancient terrestrial material. Therefore, this project will analyze another ice core from Greenland to substantiate the recent discovery and determine the nature of meteorite. The project will be performed in collaboration with Dr. Sungmin Hong at Inha University in Korea, and his collaborators at Korea Polar Research Institute, who are experts in Platinum and Iridium analyses in ice cores. This research will provide insight into the cause of an abrupt cooling climate during Younger Dryas, and advance understanding of mechanisms of climate change. The research will determine Platinum and Iridium concentrations at the onset of Younger Dryas in the North Greenland Ice Core Project (NGRIP) ice core. These analyses are technically challenging as ice samples require decontamination of the NGRIP ice core, which could have been contaminated during drilling, and high sensitivity measurements of platinum metals, whose concentrations in the ice are expected to be extremely low (in 10-15g/g or femtogram/g). This project aims to decontaminate the NGRIP ice core in ultraclean working conditions and measure Platinum and Iridium using sector-field inductively coupled plasma mass spectrometry (ICP-SFMS). This NSF EAPSI award is funded in collaboration with the National Research Foundation of Korea.