Was there a marine transgression on the Laptev Sea Shelf during the last interglacial? Evidence of continental climate in the Siberian Arctic by terrestrial plant macrofossils
Terrestrial plant macrofossils from permafrost deposits at the Bol'shoy Lyakhovsky Island, New Siberian Archipelago, Arctic Siberia, revealed the existence of subarctic forest tundra with dominating Alnus fruticosa, Betula fruticosa, B. nana, and Ledum palustre during the last interglacial (Fig...
| Main Authors: | , , , , , |
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| Format: | Conference Object |
| Language: | unknown |
| Published: |
2006
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| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/14818/ https://hdl.handle.net/10013/epic.25044 |
| Summary: | Terrestrial plant macrofossils from permafrost deposits at the Bol'shoy Lyakhovsky Island, New Siberian Archipelago, Arctic Siberia, revealed the existence of subarctic forest tundra with dominating Alnus fruticosa, Betula fruticosa, B. nana, and Ledum palustre during the last interglacial (Fig. 1). The reconstructed palaeovegetation resembled today's southern subarctic shrub tundra near the tree line occurring about 350 km SW of the study site. This low shrub tundra was however interspersed with arctic/alpine upland communities and grasslands in a more open landscape and thus differing from modern tundra in this region. Accordingly, the climate was characterised by increased evaporation, which resulted in the local persistence of steppe and meadow vegetation, the occurrence of halophytic plants reflecting salt accumulation, and littoral pioneer species, indicating fluctuating lake levels. The massive presence of southern, boreal, today extralimital plants, especially among aquatics, indicates an extended growing season and summer temperatures during the last interglacial of at least 12 °C, thus 8 °C higher than today. Such an increase in temperature in contrast to the current warm stage in arctic Siberia is not explainable by the global warming during the Eemian Interglacial alone but must be superposed by regional effects. All the climatic implications point to more continental conditions and consequently to a lower oceanic influence. Accordingly, the interglacial marine transgression possibly advanced during the Eemian not as far as it did during the Holocene.Considering an Eemian global sea level exceeding the current one by 5.5 to 6 m (Dumas et al., 2006), there are only two possible causes of that difference: a tectonic shelf subsidence or a subsidence due to thermoerosion of the ice-rich permafrost both occurring after the last interglacial(Eemian). Thermoerosion took place during both interglacials the current and the last one (Andreev et al., 2004) and thus it fails to be the only reason for an ... |
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