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Upper Holocene Stratigraphy and Pollen Case Study of Isfjorden, West Spitsbergen (Svalbardстатья
Информация о цитировании статьи получена из
Web of Science
Дата последнего поиска статьи во внешних источниках: 26 сентября 2016 г.
- Автор: Rudenko O.
- Журнал: Springer Geology
- Год издания: 2014
- Первая страница: 1309
- Последняя страница: 1315
- DOI: 10.1007/978-3-319-04364-7_251
- Аннотация: Three bottom sediment cores (140 to 190 cm long) taken from Isfjorden, West Spitsbergen, were analyzed for pollen and spores with the main aim to elucidate local pattern of pollen and spores succession in order to understand age and define stratigraphy of marine sediments. Isfjorden bottom sediments represent greyish-green silty pelite with gruss, detritus and pebble inclusions. The upper 25 cm are water-saturated and non-plastic. In spite of extremely low concentration and predominance of reworked pre-Quaternary microfossils marine pollen spectra appeared quite similar to those known from radiocarbon-dated lake sediments and peat exposures on the coasts of neighboring Billefjorden, Van Mijenfjorden and Hornsundfjorden, provided that longdistant transported pollen of conifers, tree-birches and spores of ferns are eliminated from marine pollen spectra composition. Correlation of pollen zones (PZ), which were established in fjord sediments, with those known from peat and lake sections, enabled pollen-based stratigraphy of Isfjorden bottom sediments and further reconstruction of major stages of Late Holocene terrestrial vegetation history of Western Spitsbergen. The oldest pollen records date back to about 2,8 to 3 ka. They characterize the lowermost silty pelite layer (intervals 180-150 cm in core 11 and 190-60 cm in core 14 from the SW part of the fjord). At this time mosscereal-sedge fens and heather bogs at the coastal areas co-occurred with rocky tundra vegetation at higher elevations. A marked increase in the content of Salix sp., Betula sect. Nanae-type and Ericales pollen is recorded in the upper part of pelite layer in cores 11 and 14. Similar spectra dominate core 9 from the NE inner part of the fjord. Percentage of green mosses spores is extremely low. This type of spectra is suggestive of warmer-than present climate in Western Spitsbergen. The upper water-saturated layer of all three cores contains pollen assemblages that are very similar to those identified in the Isfjorden surface sediment samples. Therefore, they have been likely accumulated during the last 2000 years. These uppermost pollen assemblages show a sharp increase in sedge pollen. This suggests the expansion of coastal fens, which can be attributed to an increase in the amount of precipitation. Extremely low pollen concentration in Isfjorden bottom sediments possibly reflects very high accumulation rate during the time of silty pelite layer sedimentation.
- Добавил в систему: Руденко Ольга Владимировна