Holocene climate variability in the Laptev and Kara seas based on aquatic palynomorphs

Despite a growing interest in the paleoclimate evolution of the Holocene period in the Siberian sector of the Arctic Ocean relatively few data are available about the marine conditions from the shallow Siberian shelf seas. Within the frame of the joint Russian-German projects "Laptev Sea" and "SIRRO" high-resolution records from the Kara and Laptev seas have been studied for their palynological content in order to reconstruct sea-surface conditions and freshwater input from the large Siberian rivers during the Holocene.Holocene dinoflagellate cyst assemblages from both the Kara and Laptev Sea indicate the presence of a marine thermal optimum in the early Holocene. The onset occurred in the Laptev Sea shortly after the transition to the Holocene while sediment cores studied so far from the inner Kara Sea do not span this period. A long-term cooling in the mid and late Holocene is recognised in both shelf seas but, obviously, major steps did not occur synchronously. The records are characterised by few sub-millennia oscillations suggesting that conditions were relatively stable in the later part of the Holocene. Chlorococcalean algae reflect a variable freshwater input during the Holocene that was related to the post-glacial sea-level rise and retreat of the estuaries of the large rivers, Ob, Yenisei and Lena to their present position

Palynological evidence for Holocene climate variability in the Laptev and Kara Seas (Eurasian Arctic)

Despite a growing interest in the paleoclimate evolution of the Holocene period in the Siberian sector of the Arctic Ocean relatively few data are available from marine records of the shallow Siberian shelf seas. Within the frame of the joint Russian-German projects "Geosystem Laptev Sea" and "Siberian River Run-off (SIRRO)" high-resolution records from the Kara and Laptev seas have been studied for their palynological contents in order to reconstruct sea-surface conditions and freshwater input from the large Siberian rivers during the Holocene.Holocene dinoflagellate cyst assemblages from both the Kara and Laptev Sea indicate the presence of a marine thermal optimum in the early Holocene. The onset occurred in the Laptev Sea shortly after the transition to the Holocene while sediment cores studied so far from the inner Kara Sea do not span this period. A long-term cooling in the mid and late Holocene is recognised in both shelf seas but, obviously, major steps did not occur synchronously. The records are characterised by few sub-millennia oscillations suggesting that conditions were relatively stable in the later part of the Holocene. Chlorococcalean algae reflect a variable freshwater input during the Holocene that was related to the post-glacial sea-level rise and retreat of the estuaries of the large rivers, Ob, Yenisei and Lena to their present positions

Rekonstruktion der Oberflaechenwassermassen der oestlichen Laptevsee im Holozaen anhand von aquatischen Palynomorphen

Summary in EnglishAvailable from TIB Hannover: RN 9219(281) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Dinoflagellate cyst assemblages as tracers of sea-surface conditions in the northern North Atlantic, Arctic and sub-Arctic seas: the new `n=677' data base and its application for quantitative palaeoceanographic reconstruction

International audienceThe distribution of dinoflagellate cyst (dinocyst) assemblages in surface sediment samples from 677 sites of the northern North Atlantic, Arctic and sub-Arctic seas is discussed with emphasis on the relationships with sea-surface parameters, including sea-ice cover, salinity and temperature of the coldest and warmest months. Difficulties in developing a circum-Arctic data base include the morphological variation within taxa (e.g. Operculodinium centrocarpum, Islandinium? cezare and Polykrikos sp.), which probably relate to phenotypic adaptations to cold and/or low salinity environments. Sparse hydrographical data, together with large interannual variations of temperature and salinity in surface waters of Arctic seas constitute additional limitations. Nevertheless, the use of the best-analogue technique with this new dinocyst data base including 677 samples permits quantitative reconstruction of sea-surface conditions at the scale of the northern North Atlantic and the Arctic domain. The error of prediction calculated from modern assemblages is +/-1.3 degreesC and +/-1.8 degreesC for the temperature of February and August, respectively, +/-1.8 for the salinity, and +/-1.5 months yr(-1) for the sea-ice cover. Application to late Quaternary sequences from the western and eastern subpolar North Atlantic (Labrador Sea and Barents Sea) provide reconstructions compatible with those obtained using the previous dinocyst data base (n = 371), which mainly included modern data from the northern North Atlantic. Copyright (C) 2001 John Wiley & Sons, Ltd