Absence of Large‐Scale Ice Masses in Central Northeast Siberia During the Late Pleistocene

• Published in: Geophysical research letters 2023-05, Vol.50 (10), p.n/a
• Main Authors: Nørgaard, Jesper, Margold, Martin, Jansen, John D., Kurbanov, Redzhep, Szuman, Izabela, Andersen, Jane Lund, Olsen, Jesper, Faurschou Knudsen, Mads
• Format: Article
• Language: English
• Subjects: Beryllium 10; boulder erratics; Boulders; cosmogenic nuclides; exposure dating; Glacial drift; glacial moraines; Glacial periods; Glaciation; Glacier mapping; Glaciers; Glaciology; Ice; Ice cover; ice sheet; Ice sheets; Isotopes; Landforms; Last Glacial Maximum; Mapping; Moisture effects; Moraine ridges; Moraines; Mountain glaciers; Pleistocene; Remote sensing; Ridges; Sequencing
• ISSN: 0094-8276; 1944-8007; 1944-8007
• DOI: 10.1029/2023GL103594

Ongoing speculation regarding the existence of large Late Pleistocene ice masses in Northeast Eurasia reflects the dearth of age constraints on glaciations across this vast region. Here, we report the first dates from the central part of Northeast Siberia, consisting of 22 cosmogenic 10Be exposure ages from boulders deriving from a sequence of three moraines in the Chersky Range. The dated moraine sequence indicates progressive contraction of maximum glacier extent from Marine Isotope Stage 6 to the Last Glacial Maximum, while the remotely‐sensed mapping indicates an older, more expansive glaciation in the region yet undated. Our results show that Late Pleistocene glaciations were limited to the highlands, and Northeast Siberia did not host a large, coalescent ice sheet during the Last Glacial Maximum or Marine Isotope Stage 6. Plain Language Summary Very little is known about the glacial history of Northeast Siberia, which has led to speculations concerning the size and timing of past ice masses in this vast region. Some have previously suggested the area was covered by a large ice sheet during the Last Glacial Maximum 20 Kyr ago, but the consensus today maintains that the ice cover was limited due to restricted moisture sources. It is clear, however, that Northeast Siberia at one point in time hosted large ice masses, as the region is home to extensive glacial landforms of unknown age. We use cosmogenic 10Be exposure dating to study a glacial moraine complex with three well‐defined moraine ridges in the Chersky Range located in central Northeast Siberia. Our results show that the youngest and innermost moraine was emplaced toward the end of the Last Glacial Maximum, whereas the oldest and outermost moraine was emplaced during the penultimate glaciation ∼130 Kyr ago. This suggests that Northeast Siberia did not host a large ice sheet during the Late Pleistocene, and that the ice cover was limited to mountain glaciers. Satellite‐based mapping of glacial landforms confirms the existence of at least one older, more expansive glaciation that remains undated. Key Points Be‐10 exposure ages from moraines in the Chersky Range show that glaciers in central NE Siberia contracted over the last two glacial cycles Northeast Siberia hosted mountain‐centered icefields during the Late Pleistocene, but no large‐scale continental ice masses Largest ice extent in the Chersky Range predates the penultimate glacial cycle and likely occurred during the Mid‐Pleistocene super‐g