How can we better understand the climate history of Eastern Canada?

Study by Kiel University provides new insights into the geological past of the Labrador Shelf off the east coast of Canada 

The Labrador Shelf is a shallow marine area on the margin of the Labrador Sea in the North Atlantic, off the east coast of Canada. During the last Ice Age, this region was covered by the Laurentide Ice Sheet, one of the largest ice masses in Earth’s history, which once covered vast parts of North America.

Until now, scientists assumed that the final ice movements at the end of the Wisconsinan glaciation — the most recent North American glacialperiod, about 22,000 years ago — had eroded older sedimentary deposits on the shelf. A new study led by Kiel University (CAU), recently published in the Journal of Quaternary Science, now revises this assumption. Using high-resolution seismic data, the researchers identified eight distinct Quaternary sedimentary units. For the first time, they were also able to detect glaciomarine and interglacial sediments preserved between glacial deposits. This is direct evidence that not only the most recent glacial period, but also earlier glacial and interglacial periods have been preserved onthe Labrador Shelf.

“Our findings clearly show that deposits from earlier glacial and interglacial periods have been preserved within the sediments of the Labrador Shelf. Contrary to previous assumptions, the seafloor of the shelf is a remarkably well-preserved archive of climate and glacial history,” explains lead author Dr. Kai-Frederik Lenz, who completed his doctoral research on this topic in the research group of Professor Dr. Sebastian Krastel at the Institute of Geosciences at Kiel University.

High-resolution seismic data sheds light on the subsurface

For the study, the scientists analyzed high-resolution 2D seismic reflection data collected during the expedition MSM84 aboard the German research vessel Maria S. Merian. These acoustic measurements reveal layer boundaries in the subsurface. The team investigated three large troughs crossing the shelf that had previously been considered to have been completely scoured by the last ice advance. 

The data allows the researchers to distinguish eight different Quaternary sediment units. The Quaternary is the most recent geological period, spanning approximately the last 2.6 million years and characterized by a constant alternation between glacial and interglacial periods. For the first time, the team also identified glaciomarine and open marine deposits that were preserved between the glacial till layers.

New geological model of the Labrador Shelf

The research team did not only succeed in mapping the stratigraphic sequences more precisely than ever before, they also identified different deposition and erosion processes. These observations were integrated into a ten-phase model describing the evolution of the Labrador Shelf from the late Pleistocene to the present. The model encompasses at least two complete glacial-interglacial cycles and demonstrates that the sedimentary deposits on the shelf are a well-preserved archive of Quaternary climate and glacial history.

Results help improve climate models

The significance of these findings extends beyond reconstructing the past: The Labrador Shelf is located within a key sector of the Atlantic Meridional Overturning Circulation (AMOC). This global ocean circulation system transports warm surface waters from the equator to northwestern Europe, thereby significantly influencing the European climate. By analyzing the sediment record, researchers can now better understand how ice sheets and ocean currents interacted in the past and how theses interactions affected the climate. The study provides an important foundation for improving climate models, including those that simulate the future evolution of the Greenland Ice Sheet and potential disruptions of the AMOC caused by meltwater input from the shrinking ice sheet. “The new results will contribute to a more reliable assessment of climate change risks,” concludes geoscientist Lenz.

The research was part of the project “Labrador Shelf Seismics at CAU” (labsCAUs), which was funded by the German Research Foundation (DFG) through the Priority Program IODP (Project No. GR 4902/2-1).

Original publication

Lenz, K.-F., Gross, F., Gebhardt, A. C., Lohrberg, A., Schneider, R., Kolling, H., et al. (2026) Refinement of the Quaternary seismic stratigraphy and analysis of buried glacial channels on the Labrador Shelf. Journal of Quaternary Science, 1–18. https://doi.org/10.1002/jqs.70099