New Faunal and Isotopic Evidence on the Late Weichselian—Holocene Oceanographic Changes in the Norwegian Sea

Downcore studies of planktonic and benthonic foraminifera and δ18O and δ13C in the planktonic foraminifer Neogloboquadrina pachyderma (sin.) in two piston cores from the southern part of the Norwegian Sea suggest large changes in the oceanic circulation pattern at the end of oxygenisotope stage 2 and in the early part of stage 1. Prior to oxygen-isotope Termination IA (16,000–13,000 yr B.P.), an isolated watermass with lower oxygen content and temperature warmer than today existed below a low salinity ice-covered surface layer in the Norwegian Sea. Close to Termination IA, well-oxygenated deep water, probably with positive temperatures, was introduced. This deep water, which must have had physical and/or chemical parameters different from those of present deep water in the Norwegian Sea, could have been introduced from the North Atlantic or been formed within the basin by another mechanism than that which forms the present deep water of the Norwegian Sea. A seasonal ice cover in the southern part of the Norwegian Sea is proposed for the period between Termination IA and the beginning of IB (close to 10,000 yr B.P.). The present situation, with strong influx of warm Atlantic surface-water and deep-water formation by surface cooling, was established at Termination IB.

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Labrador Sea bio-, tephro-, oxygen isotopic stratigraphy and Late Quaternary paleoceanographic trends

Canadian Journal of Earth Sciences ◽

10.1139/e80-083 ◽

1980 ◽

Vol 17 (7) ◽

pp. 831-854 ◽

Cited By ~ 53

Author(s):

R. H. Fillon ◽

J. C. Duplessy

Keyword(s):

Deep Water ◽

Late Quaternary ◽

Planktonic Foraminifera ◽

Open Water ◽

Labrador Sea ◽

Surface Cooling ◽

Stratigraphic Framework ◽

Stage 4 ◽

Oxygen Isotopic ◽

Stage 1

A stratigraphic framework for eastern Labrador Sea cores has been developed for the interval 0–90 000 years BP through analysis of oxygen isotopes, volcanic ash, benthonic foraminifera, and the radiolarian Diplocyclas davisiana. Benthonic and planktonic foraminiferal isotope stratigraphy and the time scale of Shackleton and Opdyke provide a basis for the approximate dating of a series of marker events which include ash zones at ca. 59 000 and ≤ 21 000 years BP; benthonic foraminiferal abundance maxima at ca. 83 000, 75 000, 60 000, 19 000, and 3000 years BP; and D. davisiana percentage maxima at ca. 90 000, 73 000, 64 000, 54 000, 45 000 – 32 000, and 10 000 years BP. Incursions of subpolar planktonic foraminifera into the area during parts of isotopic stage 2 (between about 13 000 and 25 000 years BP but probably excluding the 15 000–18 000 years BP glacial maximum interval) and during the isotopic stage 4/5a transition (around 75 000 years BP) suggest that the eastern Labrador Sea was free of sea ice, at least in summer during periods of rapid continental ice sheet growth which lead to the isotopic stage 4 and stage 2 glacial maxima. A larger than normal stage 1/stage 2 difference in the isotopic composition of benthonic foraminifera (1.8‰) implies that this open water and attendant surface cooling was a potential source for colder than modern deep water. In contrast the Norwegian Sea was a reservoir of warmer than modern deep water during the last glacial.

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Palaeo-oceanography, margin stratigraphy and palaeophysiography of the Tertiary North Atlantic and Norwegian-Greenland seas

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1980.0024 ◽

1980 ◽

Vol 294 (1409) ◽

pp. 177-185 ◽

Cited By ~ 16

Keyword(s):

North Atlantic ◽

Deep Water ◽

Global Climate ◽

Circulation Pattern ◽

The Arctic ◽

Continental Margins ◽

Long Distance ◽

Sea Level Fluctuations ◽

The North ◽

Border Zones

The Tertiary was a period of dramatic changes of the palaeo-oceanography of the world’s oceans in general and of the North Atlantic in particular. These changes were caused by (1) the bathymetric evolution of ocean basins and intrabasin pathways (opening of the Norwegian-Greenland Seas and of the pathway to the Arctic Ocean, interruption of the circumglobal equatorial seaway); (2) the geographical development of the oceans and adjacent marginal basins in the context of rapid and intensive eustatic sea level fluctuations; and (3) the deterioration of the global climate throughout the Tertiary (change from a non-glacial to a glacial world, causing major changes in circulation of the surface and deep water). A biostratigraphy of Tertiary sediments deposited close to the continental margins has been developed by using remains of planktonic floras and faunas. Their presence in these sediments and their usefulness for long distance correlations of margin sediments, depend upon the circulation pattern and hydrographic gradients of the oceanic surface and deep water masses, the climatic regime over the continental border zones, and the probability of their post-depositional preservation.

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Seasonal Barotropic Modulation of the Deep-Water Overflow through the Faroe Bank Channel

Journal of Physical Oceanography ◽

10.1175/jpo2965.1 ◽

2006 ◽

Vol 36 (12) ◽

pp. 2328-2339 ◽

Cited By ~ 11

Author(s):

Iréne Lake ◽

Peter Lundberg

Keyword(s):

North Atlantic ◽

Deep Water ◽

Satellite Altimetry ◽

North Atlantic Ocean ◽

Norwegian Sea ◽

The North ◽

Flow Through ◽

The North Atlantic ◽

Water Overflow

Abstract As a joint Nordic project, an upward-looking ADCP has been maintained at the sill of the Faroe Bank Channel from 1995 onward. Records from a period in 1998 with three current meters deployed across the channel were used to demonstrate that the Faroe Bank Channel deep-water transport from the Norwegian Sea into the North Atlantic Ocean proper can be reasonably well estimated from one centrally located ADCP. The long-term average of this transport over the period 1995–2001 was found to be 2.1 Sv (Sv ≡ 106 m−3 s−1). The transport record demonstrates a pronounced seasonality. Satellite altimetry shows that this is caused by the northbound Atlantic surface water inflow giving rise to a barotropic modulation of the deep-water flow through the Faroe–Shetland Channel and the southern reaches of the Norwegian Sea.

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Late quarterly paleooceanology of the Norwegian Sea on the basis of analysis of benthic foraminifers

Moscow University Bulletin. Series 4. Geology ◽

10.33623/0579-9406-2020-2-34-42 ◽

2020 ◽

pp. 34-42

Author(s):

L. A. Kireenko ◽

L. F. Kopaevich ◽

A. G. Matul

Keyword(s):

Deep Water ◽

Benthic Foraminifera ◽

Research Vessel ◽

Benthic Foraminifers ◽

Norwegian Sea ◽

The North ◽

North Eastern ◽

Greenland Basin ◽

North Eastern Part

Deep-water cores selected at AMK 5536 and 5524 stations on the 68th cruise of the research vessel «Academik Mstislav Keldysh» from the north-eastern part of the Norwegian-Greenland basin were investigated by sedimentological and micropaleontological methods. Changes in benthic foraminifera communities in the Norwegian Sea, their changes in time, which make it possible to use paleooceanological reconstructions and associate them with marine isotope stages are considered.

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Late Pleistocene Paleo-Oceanography of the Norwegian-Greenland Sea: Benthic Foraminiferal Evidence

Quaternary Research ◽

10.1016/0033-5894(82)90022-9 ◽

1982 ◽

Vol 18 (1) ◽

pp. 72-90 ◽

Cited By ~ 71

Author(s):

S. Stephen Streeter ◽

Paul E. Belanger ◽

Thomas B. Kellogg ◽

Jean Claude Duplessy

Keyword(s):

Oxygen Isotope ◽

North Atlantic ◽

Deep Water ◽

Benthic Foraminifera ◽

Cold Climate ◽

Near Surface ◽

Norwegian Sea ◽

The Holocene ◽

The North ◽

The North Atlantic

AbstractFluctuations in benthic foraminiferal faunas over the last 130,000 yr in four piston cores from the Norwegian Sea are correlated with the standard worldwide oxygen-isotope stratigraphy. One species, Cibicides wuellerstorfi, dominates in the Holocene section of each core, but alternates downcore with Oridorsalis tener, a species dominant today only in the deepest part of the basin. O. tener is the most abundant species throughout the entire basin during periods of particularly cold climate when the Norwegian Sea presumably was ice covered year round and surface productivity lowered. Portions of isotope Stages 6, 3, and 2 are barren of benthic foraminifera; this is probably due to lowered benthic productivity, perhaps combined with dilution by ice-rafted sediment; there is no evidence that the Norwegian Sea became azoic. The Holocene and Substage 5e (the last interglacial) are similar faunally. This similarity, combined with other evidence, supports the presumption that the Norwegian Sea was a source of dense overflows into the North Atlantic during Substage 5e as it is today. Oxygen-isotope analyses of benthic foraminifera indicate that Norwegian Sea bottom waters warmer than they are today from Substage 5d to Stage 2, with the possible exception of Substage 5a. These data show that the glacial Norwegian Sea was not a sink for dense surface water, as it is now, and thus it was not a source of deep-water overflows. The benthic foraminiferal populations of the deep Norwegian Sea seem at least as responsive to near-surface conditions, such as sea-ice cover, as they are to fluctuations in the hydrography of the deep water. Benthic foraminiferal evidence from the Norwegian Sea is insufficient in itself to establish whether or not the basin was a source of overflows into the North Atlantic at any time between the Substage 5e/5d boundary at 115,000 yr B.P. and the Holocene.

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Can the North Brazil Current Help Us Understand Atlantic Water Flow?

Eos ◽

10.1029/2015eo041571 ◽

2015 ◽

Vol 96 ◽

Author(s):

David Shultz

Keyword(s):

Water Flow ◽

Circulation Pattern ◽

Atlantic Water ◽

Oceanic Circulation ◽

The North ◽

Brazil Current ◽

North Brazil ◽

North Brazil Current ◽

Northern Brazil

Currents off the coast of northern Brazil can be used to study changes in the larger oceanic circulation pattern in the Atlantic, when variable winds in the regions are properly accounted for.

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Late Quaternary palaeo-oceanography of the Denmark Strait overflow pathway, South-East Greenland margin

Geology of Greenland Survey Bulletin ◽

10.34194/ggu-bulletin.v180.6514 ◽

1998 ◽

Vol 180 ◽

pp. 163-167

Author(s):

Antoon Kuijpers ◽

Jørn Bo Jensen ◽

Simon R . Troelstra ◽

And shipboard scientific party of RV Professor Logachev and RV Dana

Keyword(s):

North Atlantic ◽

Deep Water ◽

Deep Convection ◽

Conveyor Belt ◽

Water Masses ◽

Labrador Sea ◽

Greenland Sea ◽

The North ◽

Denmark Strait ◽

The North Atlantic

Direct interaction between the atmosphere and the deep ocean basins takes place today only in the Southern Ocean near the Antarctic continent and in the northern extremity of the North Atlantic Ocean, notably in the Norwegian–Greenland Sea and Labrador Sea. Cooling and evaporation cause surface waters in the latter region to become dense and sink. At depth, further mixing occurs with Arctic water masses from adjacent polar shelves. Export of these water masses from the Norwegian–Greenland Sea (Norwegian Sea Overflow Water) to the North Atlantic basin occurs via two major gateways, the Denmark Strait system and the Faeroe– Shetland Channel and Faeroe Bank Channel system (e.g. Dickson et al. 1990; Fig.1). Deep convection in the Labrador Sea produces intermediate waters (Labrador Sea Water), which spreads across the North Atlantic. Deep waters thus formed in the North Atlantic (North Atlantic Deep Water) constitute an essential component of a global ‘conveyor’ belt extending from the North Atlantic via the Southern and Indian Oceans to the Pacific. Water masses return as a (warm) surface water flow. In the North Atlantic this is the Gulf Stream and the relatively warm and saline North Atlantic Current. Numerous palaeo-oceanographic studies have indicated that climatic changes in the North Atlantic region are closely related to changes in surface circulation and in the production of North Atlantic Deep Water. Abrupt shut-down of the ocean-overturning and subsequently of the conveyor belt is believed to represent a potential explanation for rapid climate deterioration at high latitudes, such as those that caused the Quaternary ice ages. Here it should be noted, that significant changes in deep convection in Greenland waters have also recently occurred. While in the Greenland Sea deep water formation over the last decade has drastically decreased, a strong increase of deep convection has simultaneously been observed in the Labrador Sea (Sy et al. 1997).

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Polychaete Diversity Related to Different Mesophotic Bioconstructions along the Southeastern Italian Coast

Diversity ◽

10.3390/d13060239 ◽

2021 ◽

Vol 13 (6) ◽

pp. 239

Author(s):

Maria Flavia Gravina ◽

Cataldo Pierri ◽

Maria Mercurio ◽

Carlotta Nonnis Marzano ◽

Adriana Giangrande

Keyword(s):

Circulation Pattern ◽

High Turnover ◽

The North ◽

Α Diversity ◽

Biological Determinants ◽

High Species Richness ◽

The Mediterranean ◽

Current Circulation ◽

Italian Coast

In the different mesophotic bioconstructions recently found along the Southeastern Italian coast, polychaetes have been proved to show high species richness and diversity, hitherto never investigated. In the present study, the species composition and functional role of polychaete assemblages were analysed; the updated key to identification of the Mediterranean species of genus Eunice was presented and some taxonomic issues were also discussed. On the total of 70 species Serpulidae and Eunicida were the dominant polychaetes. Facing similar levels of α-diversity, the polychaete assemblages showed a high turnover of species along the north-south gradient, clearly according to the current circulation pattern, as well as to the different bioconstructors as biological determinants. Indeed, Serpulidae were dominant on the mesophotic bioconstructions primarily formed by the deep-sea oyster Neopycnodonte cochlear, while the Eunicida prevailed on the mesophotic bioconstructions mainly built by scleractinians. Lastly, the record of Eunice dubitata was the first for the Mediterranean and Italian fauna and proved this species to be characteristic of mesophotic bioconstructions.

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