In:
Climate of the Past, Copernicus GmbH, Vol. 19, No. 1 ( 2023-01-23), p. 159-178
Abstract:
Abstract. Arctic warming and sea level change will lead to widespread permafrost thaw
and subsequent mobilization. Sedimentary records of past warming events
during the Last Glacial–interglacial transition can be used to study the
conditions under which permafrost mobilization occurs and which changes in
vegetation on land are associated with such warming. The Amur and Yukon
rivers discharging into the Okhotsk and Bering seas, respectively, drain
catchments that have been, or remain until today, covered by permafrost.
Here we study two marine sediment cores recovered off the mouths of these
rivers. We use lignin phenols as biomarkers, which are excellently suited
for the reconstruction of terrestrial higher plant vegetation, and compare
them with previously published lipid biomarker data. We find that in the Yukon basin, vegetation change and wetland expansion
began already in the early deglaciation (ED; 14.6–19 ka). This timing is different from observed changes in the Okhotsk Sea reflecting input from the Amur basin, where wetland expansion and vegetation change occurred later in the Pre-Boreal (PB). In the two basins, angiosperm contribution and wetland extent all reached maxima during the PB, both decreasing and stabilizing after the PB. The permafrost of the Amur basin began to become remobilized in the PB. Retreat of sea ice coupled with increased sea surface temperatures in the Bering Sea during the ED might have promoted early permafrost mobilization. In modern Arctic river systems, lignin and n-alkanes are transported from land to the ocean via different pathways, i.e., surface runoff vs. erosion of deeper deposits, respectively. However, accumulation rates of lignin phenols and lipids are similar in our records, suggesting that under conditions of rapid sea level rise and shelf flooding, both types of terrestrial biomarkers are delivered by the same transport pathway. This finding suggests that the fate of terrigenous organic matter in the Arctic differs on both temporal and spatial scales.
Type of Medium:
Online Resource
ISSN:
1814-9332
DOI:
10.5194/cp-19-159-2023
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2023
detail.hit.zdb_id:
2217985-9
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