This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: 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 glacial period about 22,000 years ago—had eroded the older sedimentary deposits on the shelf. A new study led by Kiel University (CAU), recently published in the Journal of Quaternary Science, 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 on the 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.
For the study, the scientists analyzed high-resolution 2D seismic reflection data collected during the MSM84 expedition aboard the German research vessel Maria S. These acoustic measurements reveal layer boundaries in the subsurface. The team investigated three large troughs crossing the shelf that had previously been considered completely scoured by the last ice advance.
The data allow 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 preserved between the glacial till layers.
Extract — continue reading at the source.
