Northeastern Section - 53rd Annual Meeting - 2018

Paper No. 44-10
Presentation Time: 1:30 PM-5:30 PM


COOK, Timothy L., Department of Earth, Environment & Physics, Worcester State University, 486 Chandler Street, Worcester, MA 01602, LENOIR, James, Earth and Environmental Sciences, Boston College, 140 Commonwealth Avenue, Devlin Hall, Chestnut Hill, MA 02467 and CAMPBELL, Timothy D., Department of Geology, Bates College, Lewiston, ME 04240

The Mealy Mountains (53.6° N, 58.6° W) of Southeastern Labrador, Canada are a glacially sculpted mountain range with peaks exceeding 1000 m in elevation, numerous cirques, tarns, and fjord-like lakes. The region was recently protected as part of Canada’s 46th and newest national park yet has been the focus of very little prior research. In particular the timing of local deglaciation and Holocene climate history is poorly constrained. This study presents new sedimentary evidence from a network of lakes in the Mealy Mountains that record the deglaciation and post-glacial history of this little studied region. Basal sediments from multiple lakes include laminated, minerogenic glacial-lacustrine sediment that transitions to organic-rich gytga recording the deglacial to post-glacial evolution of the region. The regional retreat of the Laurentide Ice Sheet is suspected to have occurred between 9,000 and 10,000 calendar years before present. Basal radiocarbon ages from lakes in the Mealy Mountains record a delayed transition to post glacial sedimentation, suggesting either the presence of lingering local ice in the uplands of the Mealy Mountains or the possible formation of local mountain glaciers during the early Holocene. Down-core measurements of loss on ignition (LOI), magnetic susceptibility, and bulk geochemistry from scanning X-ray fluorescence help pinpoint the transition from glacial to post glacial sedimentation and provide additional insight into the post-glacial evolution of the regional landscape in response to Holocene climate change.