The Holocene marine environment of the Beaufort Shelf

Vilks, G; Wagner, F J E; Pelletier, Bernard

doi:10.4095/105634

Cited by 25 publications

(19 citation statements)

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“…Macoma inconspicua is one of few Pacific endemics found in the southwestern Canadian Arctic Archipelago. Of 101 species of molluscs identified by Wagner from the Canadian Beaufort Sea, 33% are known from both Atlantic and Pacific oceans; 5 1 % are recorded from the Atlantic but not the Pacific, and only 6% are reported from the Pacific but not the Atlantic (Vilks et al, 1979). Although the 6% shared with the Pacific distinguishes the Beaufort region from the rest of the Canadian Arctic, Atlantic affinity dominates the present fauna even there.…”

Section: Arctic Molluscsmentioning

confidence: 99%

Marine Molluscs as Indicators of Environmental Change in Glaciated North America and Greenland During the Last 18 000 Years

Dyke¹,

Dale²,

McNeely³

2007

gpq

116

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ABSTRACTDated mollusc collections are classified in assemblages to map paleo-faunistic zones. Hiatella arctica and Mya truncata account for almost half the records and comprise a restricted arctic assemblage. Arctic assemblages comprise 70% and arctic-dominated assemblages 80% of the database. Fifteen species dominate but 170 taxa are recorded. At last glacial maximum, the arctic zone extended from the Arctic Ocean to the Grand Banks. The boreal zone in the western Atlantic was compressed. The subarctic zone, which today dominates eastern Canada, was small. The boreal zone was extensive in the eastern Pacific where subarctic and arctic zones were compressed. Zones shifted northward during deglaciation and the arctic zone diversified when Bering Strait submerged 10.5-10.3 ka BP. Western Arctic molluscs during Younger Dryas time indicate shallow waters warmer than present. Major North Atlantic currents were established 9.5-9.0 ka BP. The subarctic zone extended to the head of Baffin Bay and a boreal zone became established in West Greenland 9-8 ka BP, with intensive changes about 8.5 ka BP. We relate the latter to the reduction of Mackenzie River discharge and in sea ice export to the North Atlantic as Laurentide ice withdrew from Mackenzie headwaters. The extended subarctic zone in Baffin Bay persisted until 3 ka BP and then retreated about 1000 km on the Canadian side. Boreal-subarctic molluscs in the Gulf of St. Lawrence before 9.5 ka BP derived from the glacial refugium. High boreal-subarctic molluscs farther north probably migrated from Europe. We postulate that the Labrador Current acts as a one-way valve for mollusc migrations at glacial-interglacial scales.

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Section: Arctic Molluscsmentioning

confidence: 99%

Marine Molluscs as Indicators of Environmental Change in Glaciated North America and Greenland During the Last 18 000 Years

Dyke¹,

Dale²,

McNeely³

2007

gpq

116

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“…The water circulation is dominated by the anticyclonic Beaufort Gyre that drives currents along the shelf margin. Along the coast, however, currents are driven by summer wind direction, alternating between eastward flow into the CAA and westward flow over Mackenzie Trough (see Matthiessen et al, 2000, Vilks et al, 1979. The wind direction also changes the location of the Mackenzie River plume and the salinity of the surface water in the Beaufort Sea.…”

Section: Beaufort Seamentioning

confidence: 99%

“…In contrast, Spiniferites ramosus is absent from Beaufort Sea (only present in northern Baffin Bay) and percentages of Spiniferites elongatus are slightly lower than in northern Hudson Bay. Both assemblages are under the influence of Arctic surface water Gymnodiniales 6 34 20 20 0 2 13 0 41 Gonyaulacales 2 30 15 17 8 1 13 2 33 Peridiniales 13 57 38 52 28 8 44 9 86 Dinophysiales 2 14 9 13 5 2 7 0 19 Prorocentrales 3 5 3 2 0 0 1 0 8 Phytodiniales 0 0 1 0 0 0 0 0 1 Blastodiniales 0 0 0 0 0 0 1 0 1 N 26 140 86 104 41 13 79 11 (Vilks et al, 1979), and the salinity conditions are highly variable. When northwesterly winds deflect the plume toward the east, surface salinity on the inner shelf is low.…”

Section: Comparison Of Caa and Hudson Bay Dinocyst Assemblagesmentioning

confidence: 99%

Distribution of dinoflagellate cysts in the Canadian Arctic marine region

Mudie

Rochon

2001

J Quaternary Science

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The Canadian Arctic is a major gateway for transport of freshwater from the Arctic Ocean to the North Atlantic. This region comprises the Beaufort Sea, the Canadian Arctic Archipelago (CAA) and northern sections of Baffin and Hudson bays. Subregional differences include major freshwater runoff to the Beaufort Sea and Hudson Bay, presence of Pacific and Atlantic Intermediate water in the west, and Atlantic Water in Baffin and Hudson bays. Principal component analysis of 50 core-top samples shows four subregional dinoflagellate cyst assemblages. Outer Beaufort Shelf Assemblage I is co-dominated by Operculodinium centrocarpum s.l. and Brigantedinium spp., with minor cysts of Pentapharsodinium dalei, Algidasphaeridium? minutum s.l. and cysts of Polykrikos spp. Assemblage II in the Canadian Arctic Archipelago is co-dominated by Brigantedinium spp., A.? minutum s.l. and cysts of Polykrikos spp., including two Arctic morphotypes. Assemblage III in the North Water polynya exclusively comprises A.? minutum s.l. and Brigantedinium spp. Assemblage IV in Baffin Bay is dominated by O. centrocarpum s.l. and Spiniferites spp., with Brigantedinium spp. on the shelves. The ratio of gonyaulacoid to protoperidinioid cysts (G : P) generally decreases with increased sea-ice cover, but it may also decrease in river plumes and in polynyas.

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“…helenae/E. excavatum ratio as an indication of paleosalinity (following the results of Vilks et al, 1979, for the Beaufort Sea), we must conclude that waters were the most saline during A2. However, we observe that foraminifer numbers and diversity indexes are lower in A2 than in A3, suggesting more adverse conditions.…”

Section: St-thuribementioning

confidence: 99%

Quaternary Foraminiferal Stratigraphy in Sediments of the Eastern Champlain Sea Basin, Québec

Guilbault¹

2007

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Sediments of the late-glacial Champlain Sea basin have been sampled at 18 sites in the Trois-Rivières and Québec City regions. Two successions of foraminif-eral ecozones (deep and shallow water) comparable to those previously reported from the western Champlain Sea are recognized. Faunal composition indicates an early phase (pre-A) of hyposaline waters with consistent freshwater evidence only at the southwestern limit of the area. Salinity control in pre-A could be the result of advance or retreat of an ice lobe in the Québec City region. It is followed by zone A (salinity: 25-32%o) which is in part synchronous with the formation of the St-Narcisse Moraine. In the easternmost Champlain Sea, zone A lasted approximately from 11.3 until after 10.6 ka BP, possibly up to near 10.2 ka BP. In the western part of the area, it is progressively replaced by the less saline conditions of zones B (10-25%o) and C (2-10%o). Near major freshwater inlets, thick delta sequences barren of foraminifera substitute for zones B and C. East of Trois-Rivières, zone B is probably discontinuous and does not reach Québec City. Zone C is present at only one site, west of Trois-Rivières. The shallow water zones EH and EA, contemporaneous with zones A and B, record relatively high salinities (annual maximum of up to 30 %o for EH, somewhat less for EA), zone EA suggesting also warmer summers. The paleoecological results concerning salinity do not allow detection of the diversion of Lake Agassiz outflow. The discharge envisaged by some authors may not have been large enough to detectably change salinity in the deep, late Champlain Sea. In shallow waters, the effect could have been significant but would be difficult to date because of error due to recycled old carbonate.Des sédiments tardiglaciaires de la Mer de Champlain ont été échantillonnés à 18 sites dans les régions de Trois-Rivières et de Québec. Deux séquences d'écozones à foraminifères (eau profonde et peu profonde), semblables à celles précédemment décrites dans l'ouest de la Mer de Champlain, sont reconnues. Le contenu faunique indique une première phase hyposaline (pré-A) avec des indices sûrs d'eau douce seulement à la limite sud-ouest de la région étudiée. Durant cette période, la salinité a dû être déterminée par l'avancée et le recul d'un lobe glaciaire dans la région de Québec. Suit la zone A (salinité : 25-32 %o), qui est en partie synchrone avec la formation de la Moraine de St-Narcisse. Cette zone a duré approximativement de 11,3 à 10,6 ka BP, peut-être jusqu'à près de 10,2 ka BP. Elle est suivie des zones B (10-25 %o) et C (2-10 %o) tandis que près des grands affluents d'eau douce, d'épaisses séries deltaïques dépourvues de foraminifères se substituent aux zones B et C. À l'est de Trois-Rivières, il semble que la zone B soit discontinue et ne se rende pas jusqu'à Québec. La zone C n'est observée qu'à un seul site, à l'ouest de Trois-Rivières. Deux zones peu profondes, EH et EA, contemporaines des zones A et B, se caractérisent par des salinités plutôt élevées (maximum annuel ...

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The Holocene marine environment of the Beaufort Shelf

Cited by 25 publications

References 0 publications

Marine Molluscs as Indicators of Environmental Change in Glaciated North America and Greenland During the Last 18 000 Years

Marine Molluscs as Indicators of Environmental Change in Glaciated North America and Greenland During the Last 18 000 Years

Distribution of dinoflagellate cysts in the Canadian Arctic marine region

Quaternary Foraminiferal Stratigraphy in Sediments of the Eastern Champlain Sea Basin, Québec

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