Western Canada Late Pleistocene Permafrost Caves Speleothem uranium-thorium (U/Th) Data, 2016 - 2019

• Main Author: McGee, David
• Format: Dataset
• Language: English
• Published: NSF Arctic Data Center 2020
• Subjects: Permafrost; Caves; Speleothems; Geochronology; Canada; Arctic; Yukon; permafrost
• Online Access: https://dx.doi.org/10.18739/a2vq2sb1d; https://arcticdata.io/catalog/view/doi:10.18739/A2VQ2SB1D

Given the possibility of substantial greenhouse gas release from thawing permafrost in a warmer future, as well as the threats to infrastructure from thawing permafrost, understanding the response of permafrost to past warmth is of fundamental importance. Speleothems (stalagmites and stalactites) only are expected to grow in Arctic caves when the overlying permafrost has thawed and no longer presents an impermeable barrier to seepage from the surface into the cave. In this project, we reconstruct permafrost history in western Canada during Pleistocene interglacials from 131 uranium-thorium (U/Th) ages on 74 speleothems, providing a record of when speleothems grew in Arctic caves and, consequently, under what past climatic conditions permafrost thawed. The project uses existing speleothem collections from three areas in western Canada spanning 17° of latitude and isolated to continuous permafrost zones. The U/Th dates document the extent of speleothem growth, and thus permafrost thaw, across variable interglacial conditions of the past 500 thousand years (kyr). The data suggest that permafrost in the Yukon region was largely stable over the last 500 kyr, with only limited thaw during the Marine Isotope Stage (MIS) 11 interglacial. Thawing is more common at the sites in central and southwestern Canada, but the MIS11 interglacial still stands out as the interglacial with the most permafrost melting during the last 500 kyr.