Postglacial changes of terrestrial and marine environments along the Labrador coast: palynological evidence from cores 91-045-005 and 91-045-006, Cartwright Saddle

1997 ◽  
Vol 34 (10) ◽  
pp. 1358-1365 ◽  
Author(s):  
Elisabeth Levac ◽  
Anne de Vernal
Keyword(s):  
Forest Cover ◽  
Transfer Functions ◽  
Sea Surface ◽  
Surface Conditions ◽  
Dinoflagellate Cyst ◽  
Tree Migration ◽  
Tundra Vegetation ◽  
Arboreal Pollen ◽  
Shrub Tundra ◽  
Cover Up

The palynology of cores from Cartwright Saddle led to reconstruction of sea-surface conditions on the basis of transfer functions using dinoflagellate cyst assemblages, and to correlations with vegetational history on adjacent land as derived from pollen assemblages. From deglaciation to about 8000 BP, dinoflagellate cyst assemblages dominated by Algidasphaeridium? minutum indicate Arctic-type sea-surface conditions, and pollen assemblages reveal tundra vegetation in southeastern Labrador. Codominance of A.? minutum and Brigantedinium spp. indicate persistence of cold sea-surface conditions (August temperature < 3 °C) and extensive sea-ice cover (up to 11 months/year) until ca. 6000 BP. However, the occurrence of Abies, which reached a maximum abundance at ca. 7000–6000 BP, and increasing percentages of Alnus indicate northward tree migration and development of shrub tundra as a result of warmer terrestrial conditions. Around 6000 BP, the significant occurrence of Peridinium faeroense and Nematosphaeropsis labyrinthus suggests the establishment of modern-like conditions in surface waters. This transition coincides with an abrupt increase in the abundance of Picea, associated with the regional development of spruce forests. The later marine record does not indicate any significant trend in sea-surface temperature, whereas decreasing abundance of arboreal pollen reflects opening of the forest cover in response to a slight cooling onshore. Thus, palynological analyses suggest complex changes in continental climate and marine hydrography along the coast of Labrador.

Dinoflagellate cyst distribution in high-latitude marine environments and quantitative reconstruction of sea-surface salinity, temperature, and seasonality

1994 ◽  
Vol 31 (1) ◽  
pp. 48-62 ◽  
Author(s):  
Anne de Vernal ◽  
Jean-Louis Turon ◽  
Joel Guiot
Keyword(s):  
Sea Ice ◽  
High Latitude ◽  
Transfer Functions ◽  
Ice Cover ◽  
Sea Surface ◽  
Labrador Sea ◽  
Marine Environments ◽  
Long Distance ◽  
Surface Conditions ◽  
Dinoflagellate Cyst

A data base of 179 reference sites documents the relations between the assemblages of organic-walled dinoflagellate cysts and sea-surface temperature, salinity, and seasonality throughout the North Atlantic, adjacent subpolar basins (Labrador Sea, Baffin Bay, Irminger and Iceland basins) and epicontinental environments off eastern Canada (estuary and Gulf of St. Lawrence, Hudson Bay). Principal-component analyses show close relationships between dinoflagellate cyst data and sea-surface conditions: the first component (71.1% of the variance) correlates with the winter temperature, salinity, and seasonal duration of sea-ice cover, whereas the second component (11.3% of the variance) appears mainly related to summer temperature. Transfer functions using the best analogue method were tested by reconstructing modern sea-surface conditions on the basis of the reference dinoflagellate cyst assemblages. The correlation coefficient between instrumental averages and reconstructed values ranges from 0.87 (August temperature) to 0.97 (annual duration of sea-ice cover). These transfer functions appear most accurate for the reconstruction of sea-surface conditions in marginal marine environments of high-latitude basins. The only reservation concerns the validity of reconstruction in offshore regions characterized by low productivity where sparse cyst fluxes may result from long-distance transport through currents. The transfer functions that were applied in, as an example, a late Quaternary sequence of the Davis Strait in the northern Labrador Sea, notably suggest seasonal sea-ice cover extent of 6–10 months/year and August temperature and salinity of 1–4 °C and 31–33‰, respectively, during the last glacial optimum (isotopic stage 2).

Sea surface conditions in the southern Nordic Seas during the Holocene based on dinoflagellate cyst assemblages

The Holocene ◽  
2016 ◽  
Vol 26 (5) ◽  
pp. 722-735 ◽  
Author(s):  
Nicolas Van Nieuwenhove ◽  
Astrid Baumann ◽  
Jens Matthiessen ◽  
Sophie Bonnet ◽  
Anne de Vernal
Keyword(s):  
Sea Surface ◽  
Nordic Seas ◽  
Surface Conditions ◽  
The Holocene ◽  
Dinoflagellate Cyst

Land-Ocean interactions at the southwest Greenland margin during the Holocene

2020 ◽  
Author(s):  
Estelle Allan ◽  
Anne de Vernal ◽  
Marit-Solveig Seidenkrantz ◽  
Claude Hillaire-Marcel ◽  
Christof Pearce ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Greenland Ice Sheet ◽  
Sea Surface ◽  
Human Occupation ◽  
Ice Dynamics ◽  
Surface Conditions ◽  
The Holocene ◽  
High Productivity ◽  
Holocene Thermal Maximum ◽  
Greenland Margin

&lt;p&gt;Palynomorph analysis of marine cores raised off Nuuk (southwestern Greenland) provided records of sea-surface conditions and climate-ocean-ice dynamics at centennial resolution over the last 12,000 years. Transfer functions using dinocyst assemblages provided information about the sea-ice cover, seasonal sea-surface temperature (SST) and salinity (SSS), as well as primary productivity. At about 10,000 cal. years ago, an increase in species diversity and the rapid increase of phototrophic taxa (light-dependent), marks the onset of interglacial conditions, with summer temperature increasing up to ~10&amp;#176;C during the Holocene Thermal Maximum (HTM). Low SSS and high productivity conditions are recorded during the interval, which we associate to increased meltwater and nutrient input from the Greenland Ice Sheet. After ~5000 cal. years BP, the decrease of phototrophic taxa marks a two-steps cooling associated with the Neoglacial trend. Since ~2000 cal. years BP, an increase in the high-frequency variability of sea surface conditions is noticeable. The second step change towards colder and more unstable conditions starting about 3000 cal. years BP coincides with the disappearance of the Saqqaq culture. The gap of human occupation in western Greenland, between the Dorset and the Norse settlements, i.e., from ca. 2000 to 1000 cal. years BP, may thus be linked to the highly unstable conditions in surface waters.&lt;/p&gt;

scholarly journals Postglacial Vegetational History of the Eastern Avalon Peninsula, Newfoundland, and Holocene Climatic Change Along the Eastern Canadian Seaboard

2007 ◽  
Vol 36 (1-2) ◽  
pp. 175-196 ◽  
Author(s):  
Joyce Brown Macpherson
Keyword(s):  
New England ◽  
Forest Cover ◽  
Baffin Island ◽  
Tundra Vegetation ◽  
Shrub Tundra ◽  
History Of ◽  
Tree Limit ◽  
Continuous Presence ◽  
Open Woodland ◽  
Avalon Peninsula

ABSTRACT Two radiocarbon-dated pollen profiles from the eastern Avalon Peninsula suggest late déglaciation (probably no earlier than 9700 BP at the coast), followed by a brief period of tundra vegetation. After 9300 BP a rich shrub tundra at lower elevations was invaded by spruce, balsam fir and tree birch until at ca 8400 BP the vegetation was an open woodland. The forest remained open for the next 3000 years; evidence of fire and the continuous presence of Populus suggest drier and warmer conditions than at present. The period of maximum warmth, ca 5400-3200 BP, saw the closing of the forest cover, a rise in the level of the tree limit in the interior upland and an increase in precipitation. After 3200 BP decreasing temperatures resulted in a lowering of the tree limit. The climatic changes inferred for the Avalon Peninsula are compared with those inferred from palaeo-environmental studies along the eastern North American seaboard from Baffin Island to New England. A sequence of changing controls on the regional atmospheric circulation during the Holocene is suggested.

Holocene variations of sea-surface conditions in the southeastern Barents Sea, reconstructed from dinoflagellate cyst assemblages

2001 ◽  
Vol 16 (7) ◽  
pp. 717-726 ◽  
Author(s):  
Elena Voronina ◽  
Leonid Polyak ◽  
Anne De Vernal ◽  
Odile Peyron
Keyword(s):  
Barents Sea ◽  
Sea Surface ◽  
Surface Conditions ◽  
Dinoflagellate Cyst
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