| Summary: | This NSF funded project was dedicated to testing the idea that the Younger Dryas cold epoch (~13,000 to ~12700 years Before Present) was caused by a massive flood of fresh water via Mackenzie River to the eastern Beaufort Sea. It was noted in a 1975 paper in Science by Kennett and Shackleton that the flood of fresh water down Mississippi River was interrupted at about 13 ka, even though there was no reason to suspect a pause in glacial ice melt. The Kennett and Shackleton hypothesis led to the expectation that as glacial ice continued to melt and retreat northward, at some point eastern outlets for meltwater must have opened to the St. Lawrence system around the time the Mississippi flood ended. However, researchers looked for decades for the signal of low d18-O in planktonic foraminifera off eastern Canada, to no avail. The only other logical direction for meltwater would have been to the north through Mackenzie River. Two piston cores recovered during HLY 2013 near Mackenzie River have the low d18-O signal of the flood beginning at 12.9 ka according to radiocarbon dating. Those flood waters most likely reduced the surface ocean salinity in the Nordic Seas, reducing the production of deep water, and thereby reducing the northward the flux of warm salty waters that account for the temperate climate in northern Europe today. This flood was most likely the trigger for the younger Dryas cooling. Analytical data associated with this project, and especially those data published in Keigwin et al. (2018, "Deglacial floods in the Beaufort Sea preceded Younger Dryas cooling," Nature Geoscience, dos/10.1038/s41561-018-0169-6), can be found in the NOAA WDS paleoclimatology database (https://www.ncdc.noaa.gov/paleo/study/24790). Those data are mostly the metadata, the chronology, and the stable isotope results. The metadata are repeated here. Supplementary information to Keigwin et al. 2018 may be found at the Nature Geoscience url shown above. Underway geophysical data can be found here: doi.org/10.18739/A2FB4WK7X.
|
|---|