Late Quaternary sporadic development of Desmophyllum dianthus deep-coral populations in the southern Labrador Sea with specific attention to their 14C- and 230Th-dating

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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The Labrador Sea during the late Quaternary: Introduction

Canadian Journal of Earth Sciences ◽

10.1139/e94-001 ◽

1994 ◽

Vol 31 (1) ◽

pp. 1-4 ◽

Cited By ~ 6

Author(s):

Claude Hillaire-Marcel ◽

Anne de Vernal ◽

Marc Lucotte ◽

Alfonso Mucci

Keyword(s):

Late Quaternary ◽

Labrador Sea

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Magnetic properties and paleointensity records frome late quaternary Labrador sea sediments =

10.1522/1533115 ◽

1995 ◽

Author(s):

Joseph Stephen. Stoner

Keyword(s):

Magnetic Properties ◽

Late Quaternary ◽

Labrador Sea

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The Last Interglacial in the Labrador Sea: a sedimentary ancient DNA investigation

10.5194/egusphere-egu21-3587 ◽

2021 ◽

Author(s):

Danielle Grant ◽

Kristine Steinsland ◽

Sigrid Mugu ◽

Katrine Sandnes Skaar ◽

Umer Z. Ijaz ◽

...

Keyword(s):

Ancient Dna ◽

Late Quaternary ◽

Greenland Ice Sheet ◽

Small Subunit ◽

Labrador Sea ◽

Time Interval ◽

Climate Projections ◽

Last Interglacial ◽

Climate Conditions ◽

Spin Column

<p>The Last Interglacial (LIG, ~128&#8211;116ka) was characterized by a warmer climate, increased sea level, and a reduced Greenland ice sheet compared to today. Climate projections suggest our future climate may resemble LIG conditions if anthropogenic climate change progresses unabated. Previous studies have identified key shifts in the Labrador Sea oceanography and climate before, during, and after the LIG, making this time interval an exciting target for exploring high-latitude marine ecological dynamics. In recent years, the application of sedimentary ancient DNA (sedaDNA) has provided new glimpses into past ocean and climate conditions. Here, we have explored sedaDNA alongside other, traditional, paleoceanography proxies, to better understand the changing Labrador Sea biome across climate transitions and in a globally warmer world. We have generated a sedaDNA record from a giant piston core at the Eirik Drift (Labrador Sea). Our sedaDNA record, dating back to ~135 ka, was sampled at 4 cm depth intervals and covers the glacial-interglacial transition, as well as the LIG. SedaDNA was purified using a commercial spin column kit and analysed using a metabarcoding approach targeting the V7 hypervariable region of the eukaryote small subunit RNA. Illumina MiSeq analysis of metabarcoding libraries revealed PCR-amplifiable eukaryotic DNA throughout the investigated downcore section. Shifts in relative taxon abundance and alpha- and beta-diversity metrics paralleled shifts in foraminifer isotope records (&#948;<sup>18</sup>&#927;), palynological assemblages, and biomarkers suggesting that the molecular genetic signal preserved in downcore sediments shows promise for identifying ecological shifts across the LIG. We are currently investigating the potential utility of specific taxa identified in the sedaDNA record to act as indicators of the glacial-interglacial transition. This study strengthens the growing potential of marine sedaDNA as a supplemental proxy for climate reconstructions in the Late Quaternary.</p>

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Late Quaternary (Stage 2 and 3) Meltwater and Heinrich Events, Northwest Labrador Sea

Quaternary Research ◽

10.1006/qres.1994.1003 ◽

1994 ◽

Vol 41 (1) ◽

pp. 26-34 ◽

Cited By ~ 101

Author(s):

John T. Andrews ◽

Helmut Erlenkeuser ◽

Katherine Tedesco ◽

Ali E. Aksu ◽

A.J.Timothy Jull

Keyword(s):

North Atlantic ◽

Late Quaternary ◽

Planktonic Foraminifera ◽

Ice Sheet ◽

Laurentide Ice Sheet ◽

Labrador Sea ◽

Near Surface ◽

Heinrich Events ◽

Eastern Margin ◽

Detrital Carbonate

AbstractTwo major meltwater events are documented in cores from the NW Labrador Sea. One occurred ca. 20,000 14C yr B.P. in association with deposition of a major detrital carbonate unit. Both prior to and after this event, δ18O values of near-surface planktonic foraminifera were 4.5%, indicating fully enriched glacial values. A younger event (ca. 14,000 14 C yr B.P.) is characterized by a dramatic change in δ18O from 4.5 to 2.0% and coincided with the retreat of ice from the outer SE Baffin Shelf, possibly into Hudson Strait. These meltwater events coincide with Heinrich (H) layers 1 and 2 from North Atlantic sediments. The 14,000 14C yr B.P. meltwater event indicates that the eastern margin of the Laurentide Ice Sheet also underwent rapid retreat at approximately the same time as other ice sheet margins around the NE North Atlantic. A third major detrital carbonate event at the base of HU87-033-009, possibly correlative with Heinrich layer 3, occurred ca. 33,960 ± 675 14 C yr B.P.; however, this is older than the accepted date for H-3 of 27,000 14C yr B.P. and may be H-4.

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