scholarly journals Cenozoic Relative Movements of Greenland and North America by Closure of the North Atlantic-arctic Plate Circuit: the Labrador Sea, Davis Strait and Baffin Bay

2021 ◽  
Author(s):  
Annabel Causer ◽  
Graeme Eagles ◽  
Lucía Pérez-Díaz ◽  
Jürgen Adam
Keyword(s):  
North America ◽  
North Atlantic ◽  
Data Uncertainty ◽  
Plate Motion ◽  
Labrador Sea ◽  
Motion Model ◽  
Continental Breakup ◽  
Baffin Bay ◽  
The North ◽  
Davis Strait

Abstract The processes that accommodated plate divergence between Greenland and North America are most confidently interpretable from a short-lived (61-42 Ma) sequence of magnetic isochrons in the Labrador Sea. Understanding of the preceding and following periods is impeded by the lack of clear isochrons in the basin’s continent-ocean transition and axial zones. By closing the regional plate circuit, we build and interpret a detailed plate motion model for Greenland and North America that is applicable in, but unaffected by data uncertainty from, the Labrador Sea, Davis Strait, and Baffin Bay. Among our findings, we show the Labrador Sea initially opened during a ~8.3-16.5 Myr-long period of focused extension culminating in continental breakup no earlier than 74-72 Ma, and experienced a ~80° change in spreading direction around 56 Ma. We describe some possible implications for the accommodation of strain prior to continental breakup and during extreme spreading obliquity.

scholarly journals Full-fit reconstruction of the Labrador Sea and Baffin Bay

2013 ◽  
Vol 5 (2) ◽  
pp. 917-962 ◽  
Author(s):  
M. Hosseinpour ◽  
R. D. Müller ◽  
S. E. Williams ◽  
J. M. Whittaker
Keyword(s):  
North America ◽  
Continental Crust ◽  
Seafloor Spreading ◽  
Labrador Sea ◽  
Gravity Inversion ◽  
Seismic Profiles ◽  
Baffin Bay ◽  
Davis Strait ◽  
Break Up ◽  
Magnetic Lineations

Abstract. Reconstructing the opening of the Labrador Sea and Baffin Bay between Greenland and North America remains controversial. Recent seismic data suggest that magnetic lineations along the margins of the Labrador Sea, originally interpreted as seafloor spreading anomalies, may lie within the crust of the continent–ocean transition. These data also suggest a more seaward extent of continental crust within the Greenland margin near the Davis Strait than assumed in previous full-fit reconstructions. Our study focuses on reconstructing the full-fit configuration of Greenland and North America using an approach that considers continental deformation in a quantitative manner. We use gravity inversion to map crustal thickness across the conjugate margins, and assimilate observations from available seismic profiles and potential field data to constrain the likely extent of different crustal types. We derive end-member continental margin restorations following alternative interpretations of published seismic profiles. The boundaries between continental and oceanic crust (COB) are restored to their pre-stretching locations along small circle motion paths across the region of Cretaceous extension. Restored COBs are fitted quantitatively to compute alternative total-fit reconstructions. A preferred full-fit model is chosen based on the strongest compatibility with geological and geophysical data. Our preferred model suggests that (i) the COB lies oceanward of magnetic lineations interpreted as magnetic anomaly 31 (70 Ma) in the Labrador Sea, (ii) all previously identified magnetic lineations landward of anomaly 27 reflect intrusions into continental crust, and (iii) the Ungava fault zone in Davis Strait acted as a leaky transform fault during rifting. This robust plate reconstruction reduces gaps and overlaps in the Davis Strait and suggests that there is no need for alternative models proposed for reconstructions of this area including additional plate boundaries in North America or Greenland. Our favored model implies that break up and formation of continent–ocean transition (COT) first started in the southern Labrador Sea and Davis Strait around 88 Ma and then propagated north and southwards up to onset of real seafloor spreading at 63 Ma in the Labrador Sea. In the Baffin Bay, continental stretching lasted longer and actual break up and seafloor spreading started around 61 Ma (Chron 26).

Isotopic evidence for changes in the origin and cycling of nitrogen in the Labrador Sea during the last 8,000 years

2020 ◽  
Author(s):  
Markus Kienast ◽  
Sam Davin ◽  
Kristin Doering ◽  
Dierk Hebbeln ◽  
Stephanie Kienast ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Water Column ◽  
North Atlantic ◽  
North Pacific ◽  
Isotopic Signature ◽  
Labrador Sea ◽  
Nitrate Sources ◽  
Baffin Bay ◽  
The North ◽  
The North Atlantic

<p>Subsurface nitrate in the Labrador Sea (NW Atlantic) and Baffin Bay is provided by North Pacific water flowing through Bering Strait and the Canadian Arctic as well as by advection from the North Atlantic. Both these nitrate sources are distinct in their isotopic signature (δ<sup>15</sup>N), owing to benthic denitrification on the Bering, Chukchi and east Siberian shelves and nitrogen fixation in the North Atlantic, respectively. Accordingly, water column profiles of δ<sup>15</sup>N<sub>(nitrate)</sub> collected off Greenland in the eastern Labrador Sea show low δ<sup>15</sup>N<sub>(nitrate)</sub>, which mixes with more <sup>15</sup>N-enriched nitrate flowing through Baffin Bay into the northern Labrador Sea. The Labrador Current carries this mixture southward along the western Labrador Sea, toward Newfoundland. The δ<sup>15</sup>N of surface sediments in the Labrador Sea closely mirrors these water column signals, suggesting that sediments can be used to trace changes in both the source signature of Atlantic versus Pacific-derived nitrate as well as in the admixture of the two source waters.</p><p>Two downcore sedimentary δ<sup>15</sup>N records from the NE and NW Labrador Sea coast both show high δ<sup>15</sup>N values of ca. 7‰ during the early Holocene (9-7 kyrs BP). In the NE Labrador Sea, this is followed by a long-term decrease toward δ<sup>15</sup>N of ca. 4.5‰ at the core top, in contrast to a much more subtle decrease in the NW Labrador Sea (surface sediment δ<sup>15</sup>N of ca. 6.5‰). The decreasing δ<sup>15</sup>N values along the eastern Labrador Sea are consistent with a Holocene increase in nitrogen fixation in the North Atlantic or an increasing advection of isotopically light nitrate. In turn, an increasing admixture of North-Pacific-derived nitrate, or intensified denitrification on the Bering Shelf would be required to explain the much subdued Holocene δ<sup>15</sup>N decrease in the NW Labrador Sea.</p>

scholarly journals Month-to-Month Variability of Winter Temperature over Northeast China Linked to Sea Ice over the Davis Strait–Baffin Bay and the Barents–Kara Sea

2019 ◽  
Vol 32 (19) ◽  
pp. 6365-6384 ◽  
Author(s):  
Haixia Dai ◽  
Ke Fan ◽  
Jiping Liu
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Northeast China ◽  
Rossby Waves ◽  
Kara Sea ◽  
Negative Phase ◽  
Baffin Bay ◽  
The North ◽  
Davis Strait ◽  
The North Atlantic

Abstract This study focuses on the month-to-month variability of winter temperature anomalies over Northeast China (NECTA), especially the out-of-phase change between December and January–February (colder than normal in December and warmer than normal in January–February, and vice versa), which accounts for 30% of the past 37 years (1980–2016). Our analysis shows that the variability of sea ice concentration (SIC) in the preceding November over the Davis Strait–Baffin Bay (SIC_DSBB) mainly affects NECTA in December, whereas the SIC over the Barents–Kara Sea (SIC_BKS) significantly impacts NECTA in January–February. A possible reason for the different effects of SIC_DSBB and SIC_BKS on NECTA is that the month-to-month increments (here called DM) of SIC over these two areas between October and November are different. A smaller DM of SIC_DSBB in November can generate eastward-propagating Rossby waves toward East Asia, whereas a larger DM of SIC_BKS can affect upward-propagating stationary Rossby waves toward the stratosphere in November. Less than normal SIC_DSBB in November corresponds to a negative phase of the sea surface temperature tripole pattern over the North Atlantic, which contributes to a negative phase of the North Atlantic Oscillation (NAO)-like geopotential height anomalies via the eddy-feedback mechanism, ultimately favoring cold conditions over Northeast China. However, positive November SIC_BKS anomalies can suppress upward-propagating Rossby waves that originate from the troposphere in November, strengthening the stratospheric polar vortex and leading to a positive phase of an Arctic Oscillation (AO)-like pattern in the stratosphere. Subsequently, these stratospheric anomalies propagate downward, causing the AO-like pattern in the troposphere in January–February, favoring warm conditions in Northeast China, and vice versa.

scholarly journals III. On some Foraminifera from the North Atlantic and Arctic Oceans, including Davis Strait and Baffin Bay

1864 ◽  
Vol 13 ◽  
pp. 239-240
Keyword(s):  
Natural History ◽  
North Atlantic ◽  
North American ◽  
Baffin Bay ◽  
The North ◽  
Sea Bottom ◽  
Davis Strait ◽  
External Relationships ◽  
The North Atlantic ◽  
First Time

Having received specimens of sea-bottom, by favour of friends, from Baffin Bay (soundings taken in one of Sir E. Parry’s expeditions), from the Hunde Islands in Davis Strait (dredgings by Dr. P. C. Sutherland), from the coast of Norway (dredgings by Messrs. M‘Andrew and Barrett), and from the whole width of the North Atlantic (soundings by Commander Dayman), the authors have been enabled to form a tolerably correct esti­mate of the range and respective abundance of several species of Foraminifera in the Northern seas; and the more perfectly by taking Professor Williamson’s and Mr. H. B. Brady’s researches in British Foraminifera as supplying the means of estimating the Foraminiferal fauna of the shallower sea-zones at the eastern end of the great “Celtic Province,” and the less perfect researches of Professor Bailey on the North American coast, for the opposite, or “Virginian” end,—thus presenting for the first time the whole of a Foraminiferal fauna as a natural-history group, with its internal and external relationships.

scholarly journals Full-fit reconstruction of the Labrador Sea and Baffin Bay

Solid Earth ◽  
2013 ◽  
Vol 4 (2) ◽  
pp. 461-479 ◽  
Author(s):  
M. Hosseinpour ◽  
R. D. Müller ◽  
S. E. Williams ◽  
J. M. Whittaker
Keyword(s):  
North America ◽  
Continental Crust ◽  
Seafloor Spreading ◽  
Labrador Sea ◽  
Gravity Inversion ◽  
Seismic Profiles ◽  
Baffin Bay ◽  
Davis Strait ◽  
Break Up ◽  
Magnetic Lineations

Abstract. Reconstructing the opening of the Labrador Sea and Baffin Bay between Greenland and North America remains controversial. Recent seismic data suggest that magnetic lineations along the margins of the Labrador Sea, originally interpreted as seafloor spreading anomalies, may lie within the crust of the continent–ocean transition. These data also suggest a more seaward extent of continental crust within the Greenland margin near Davis Strait than assumed in previous full-fit reconstructions. Our study focuses on reconstructing the full-fit configuration of Greenland and North America using an approach that considers continental deformation in a quantitative manner. We use gravity inversion to map crustal thickness across the conjugate margins, and assimilate observations from available seismic profiles and potential field data to constrain the likely extent of different crustal types. We derive end-member continental margin restorations following alternative interpretations of published seismic profiles. The boundaries between continental and oceanic crust (COB) are restored to their pre-stretching locations along small circle motion paths across the region of Cretaceous extension. Restored COBs are fitted quantitatively to compute alternative total-fit reconstructions. A preferred full-fit model is chosen based on the strongest compatibility with geological and geophysical data. Our preferred model suggests that (i) the COB lies oceanward of magnetic lineations interpreted as magnetic anomaly 31 (70 Ma) in the Labrador Sea, (ii) all previously identified magnetic lineations landward of anomaly 27 reflect intrusions into continental crust and (iii) the Ungava fault zone in Davis Strait acted as a leaky transform fault during rifting. This robust plate reconstruction reduces gaps and overlaps in Davis Strait and suggests that there is no need for alternative models proposed for reconstructions of this area including additional plate boundaries in North America or Greenland. Our favoured model implies that break-up and formation of continent–ocean transition (COT) first started in the southern Labrador Sea and Davis Strait around 88 Ma and then propagated north and southwards up to the onset of real seafloor spreading at 63 Ma in the Labrador Sea. In Baffin Bay, continental stretching lasted longer and actual break-up and seafloor spreading started around 61 Ma (chron 26).

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