Geophysical Studies in Baffin Bay and some Tectonic Implications

1972 ◽  
Vol 9 (3) ◽  
pp. 239-256 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett ◽  
K. S. Manchester ◽  
D. I. Ross
Keyword(s):  
Oceanic Crust ◽  
Seismic Reflection ◽  
Seismic Refraction ◽  
The Arctic ◽  
Spreading Center ◽  
Labrador Sea ◽  
Baffin Bay ◽  
Definitive Evidence ◽  
Nares Strait ◽  
The North

A recent seismic refraction experiment in the deep central region of Baffin Bay showed that it is underlain by oceanic crust. This paper describes the results of gravity, magnetic, and seismic reflection profiling measurements in the bay. There is no definitive evidence for a buried ridge or for magnetic lineations in the center of the area. The magnetic and gravity anomaly fields have been used to define the boundary between the oceanic and continental crust around the bay and therefore the extent of oceanic crust presumed to have been formed by sea-floor spreading. Some of the characteristics of the seismic reflection lines across the continental margins, perhaps typical of this area, are also discussed. The results have been used to reconstruct the history of opening of Baffin Bay in conjuction with geophysical measurements in the Labrador Sea to the south and over the Alpha Ridge in the Arctic Ocean to the north. An attempt has been made to reconcile the geometry of opening with continental geology. Two phases of spreading are suggested. The first involves openings, in both the Labrador Sea and in Baffin Bay, about a pole in the Canadian Arctic Islands. The second, most recent stage of opening, requires that the Nares Strait was once a transform fault, perhaps connecting a Baffin Bay spreading center to the Alpha Ridge to the north.

Radiogenic Isotope Signatures of Holocene Sediments from Kane Basin: Linkage with the Re-opening and Evolution of Nares Strait

2021 ◽  
Author(s):  
Lina Madaj ◽  
Friedrich Lucassen ◽  
Claude Hillaire-Marcel ◽  
Simone A. Kasemann
Keyword(s):  
Ellesmere Island ◽  
The Arctic ◽  
Baffin Bay ◽  
Low Salinity ◽  
The Core ◽  
The Past ◽  
Nares Strait ◽  
The North ◽  
Sediment Input ◽  
Detrital Sediment

<p>The re-opening of the Arctic Ocean-Baffin Bay gateway through Nares Strait, following the Last Glacial Maximum, has been partly documented, discussed and revised in the past decades. The Nares Strait opening has led to the inception of the modern fast circulation pattern carrying low-salinity Arctic water towards Baffin Bay and further towards the Labrador Sea. This low-salinity water impacts thermohaline conditions in the North Atlantic, thus the Atlantic Meridional Overturning Circulation. Available land-based and marine records set the complete opening between 9 and 7.5 ka BP [1-2], although the precise timing and intensification of the southward flowing currents is still open to debate. A recent study of a marine deglacial sedimentary record from Kane Basin, central Nares Strait, adds information about subsequent paleoceanographic conditions in this widened sector of the strait and proposed the complete opening at ~8.3 ka BP [3].</p><p>We present complementary radiogenic strontium, neodymium and lead isotope data of the siliciclastic detrital sediment fraction of this very record [3] further documenting the timing and pattern of Nares Strait opening from a sediment provenance approach. The data permit to distinguish detrital material from northern Greenland and Ellesmere Island, transported to the core location from both sides of Nares Strait. Throughout the Holocene, the evolution of contributions of these two sources hint to the timing of the ice break-up in Kennedy Channel, north of Kane Basin, which led to the complete opening of Nares Strait [3]. The newly established gateway of material transported to the core location from the north via Kennedy Channel is recorded by increased contribution of northern Ellesmere Island detrital sediment input. This shift from a Greenland (Inglefield Land) dominated sediment input to a northern Ellesmere Island dominated sediment input supports the hypothesis of the newly proposed timing of the complete opening of Nares Strait at 8.3 ka BP [3] and highlights a progressive trend towards modern-like conditions, reached at about 4 ka BP.</p><p>References:</p><p>[1] England (1999) Quaternary Science Reviews, 18(3), 421–456. [2] Jennings et al. (2011) Oceanography, 24(3), 26-41. [3] Georgiadis et al. (2018) Climate of the Past, 14 (12), 1991-2010.</p>

Hydrographic Changes in Nares Strait (Canadian Arctic Archipelago) in Recent Decades Based on δ18O Profiles of Bivalve Shells

ARCTIC ◽  
2011 ◽  
Vol 64 (1) ◽  
pp. 45 ◽  
Author(s):  
Marta E. Torres ◽  
Daniela Zima ◽  
Kelly K. Falkner ◽  
Robie W. Macdonald ◽  
Mary O'Brien ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Past Century ◽  
Depth Range ◽  
Baffin Bay ◽  
Nares Strait ◽  
The North ◽  
The Arctic Ocean ◽  
Oxygen Isotopic ◽  
Bivalve Shells

<span style="font-family: 'Times New Roman';">Nares Strait is one of three main passages of the Canadian Archipelago that channel relatively fresh seawater from the Arctic Ocean through Baffin Bay to the Labrador Sea. Oxygen isotopic profiles along the growth axis of bivalve shells, collected live over the 5 – 30 m depth range from the Greenland and Ellesmere Island sides of the strait, were used to reconstruct changes in the hydrography of the region over the past century. The variability in oxygen isotope ratios is mainly attributed to variations in salinity and suggests that the northern end of Nares Strait has been experiencing an increase in freshwater runoff since the mid 1980s. The recent changes are most pronounced at the northern end of the strait and diminish toward the south, a pattern consistent with proximity to the apparently freshening Arctic Ocean source in the north and mixing with Baffin Bay waters as the water progresses southward. This increasing freshwater signal may reflect changes in circulation and ice formation that favor an increased flow of relatively fresh waters from the Arctic Ocean into Nares Strait. </span>

scholarly journals Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebecca Jackson ◽  
Anna Bang Kvorning ◽  
Audrey Limoges ◽  
Eleanor Georgiadis ◽  
Steffen M. Olsen ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Active Role ◽  
Atlantic Water ◽  
The Arctic ◽  
Negative Consequences ◽  
Baffin Bay ◽  
The North ◽  
North Water ◽  
History Of ◽  
Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

scholarly journals Interpretation of Slar Imagery of Sea Ice in Nares Strait and the Arctic Ocean

1975 ◽  
Vol 15 (73) ◽  
pp. 193-213
Author(s):  
Moira Dunbar
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
North Pole ◽  
The Arctic ◽  
Canadian Forces ◽  
Nares Strait ◽  
The North ◽  
The Arctic Ocean ◽  
Ice Edge ◽  
Airborne Sensors

AbstractSLAR imagery of Nares Strait was obtained on three flights carried out in. January, March, and August of 1973 by Canadian Forces Maritime Proving and Evaluation Unit in an Argus aircraft equipped with a Motorola APS-94D SLAR; the March flight also covered two lines in the Arctic Ocean, from Alert 10 the North Pole and from the Pole down the long. 4ºE. meridian to the ice edge at about lat. 80º N. No observations on the ground were possible, but -some back-up was available on all flights from visual observations recorded in the air, and on the March flight from infrared line-scan and vertical photography.The interpretation of ice features from the SLAR imagery is discussed, and the conclusion reached that in spite of certain ambiguities the technique has great potential which will increase with improving resolution, Extent of coverage per distance flown and independence of light and cloud conditions make it unique among airborne sensors.

The Effect of Arctic Freshwater Pathways on North Atlantic Convection and the Atlantic Meridional Overturning Circulation

2018 ◽  
Vol 31 (13) ◽  
pp. 5165-5188 ◽  
Author(s):  
He Wang ◽  
Sonya Legg ◽  
Robert Hallberg
Keyword(s):  
North Atlantic ◽  
Climate Models ◽  
Deep Convection ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Labrador Sea ◽  
Overturning Circulation ◽  
The North ◽  
Meridional Overturning

This study examines the relative roles of the Arctic freshwater exported via different pathways on deep convection in the North Atlantic and the Atlantic meridional overturning circulation (AMOC). Deep water feeding the lower branch of the AMOC is formed in several North Atlantic marginal seas, including the Labrador Sea, Irminger Sea, and the Nordic seas, where deep convection can potentially be inhibited by surface freshwater exported from the Arctic. The sensitivity of the AMOC and North Atlantic to two major freshwater pathways on either side of Greenland is studied using numerical experiments. Freshwater export is rerouted in global coupled climate models by blocking and expanding the channels along the two routes. The sensitivity experiments are performed in two sets of models (CM2G and CM2M) with different control simulation climatology for comparison. Freshwater via the route east of Greenland is found to have a larger direct impact on Labrador Sea convection. In response to the changes of freshwater route, North Atlantic convection outside of the Labrador Sea changes in the opposite sense to the Labrador Sea. The response of the AMOC is found to be sensitive to both the model formulation and mean-state climate.

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

&lt;p&gt;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 (&amp;#948;&lt;sup&gt;15&lt;/sup&gt;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 &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;(nitrate)&lt;/sub&gt; collected off Greenland in the eastern Labrador Sea show low &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;(nitrate)&lt;/sub&gt;, which mixes with more &lt;sup&gt;15&lt;/sup&gt;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 &amp;#948;&lt;sup&gt;15&lt;/sup&gt;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.&lt;/p&gt;&lt;p&gt;Two downcore sedimentary &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N records from the NE and NW Labrador Sea coast both show high &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N values of ca. 7&amp;#8240; during the early Holocene (9-7 kyrs BP). In the NE Labrador Sea, this is followed by a long-term decrease toward &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N of ca. 4.5&amp;#8240; at the core top, in contrast to a much more subtle decrease in the NW Labrador Sea (surface sediment &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N of ca. 6.5&amp;#8240;). The decreasing &amp;#948;&lt;sup&gt;15&lt;/sup&gt;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 &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N decrease in the NW Labrador Sea.&lt;/p&gt;

Crustal Structure of Baffin Bay from the Earthquake-generated Lg Phase

1974 ◽  
Vol 11 (1) ◽  
pp. 123-130 ◽  
Author(s):  
R. J. Wetmiller
Keyword(s):  
Oceanic Crust ◽  
Crustal Structure ◽  
Propagation Path ◽  
Baffin Island ◽  
Intermediate Type ◽  
Baffin Bay ◽  
Nares Strait ◽  
Earthquake Record ◽  
Cape York ◽  
Sufficient Proof

The Lg phase generated by earthquakes is used to infer the gross crustal structure of Baffin Bay. The principle of interpretation is that the presence of the Lg phase on an earthquake record is sufficient proof of the existence of continental crustal structure along the entire propagation path, while the absence of the Lg phase is a consequence but not sufficient proof of the existence of a section of oceanic crust somewhere along the propagation path. Examples are given of earthquake records involving propagation paths through three distinct types of gross crustal structure, namely shield-type continental, intermediate-type continental, and oceanic. These examples are used to interpret the records at four seismic observatories located around Baffin Bay for eleven earthquakes, which occurred in and around the Bay in the years 1965 to 1967. The records reveal two areas of Baffin Bay that appear to have oceanic crust, one in the northern part of the Bay at the entrance to Nares Strait, and one in the deep central part of the Bay separated by a bridge of continental crust from Cape York on Greenland to Cape Macculloch on Baffin Island.

Geophysical measurements in the region of the Explorer ridge off western Canada

1978 ◽  
Vol 15 (9) ◽  
pp. 1508-1525 ◽  
Author(s):  
R. D. Hyndman ◽  
G. C. Rogers ◽  
M. N. Bone ◽  
C. R. B. Lister ◽  
U. S. Wade ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Seismic Refraction ◽  
Ocean Bottom ◽  
Low Velocity ◽  
Geothermal Heat ◽  
Juan De Fuca Plate ◽  
The North ◽  
The Pacific ◽  
Ocean Bottom Seismometers ◽  
Seismic Reflection Profiles

The region of the Explorer spreading centre off Vancouver Island, British Columbia, has been studied through a marine geophysical survey. Earthquake epicentres located by three ocean bottom seismometers confirm that the boundary between the Pacific plate and the Explorer plate (the northern extension of the Juan de Fuca plate) at present lies along the Sovanco fracture zone, the Explorer ridge, and the Dellwood Knolls. The epicentres of earthquakes in this area as determined by the onshore seismic network are found to be subject to significant errors. The ocean bottom seismometers also have been used for a detailed seismic refraction line just to the north of the Explorer spreading centre employing explosives and a large airgun as sources. A preliminary analysis of the data indicates a fairly typical crustal structure but a shallow and low velocity mantle near the ridge crest, and illustrates the value of ocean bottom seismometers in oceanic refraction studies. A new geothermal heat flux probe was employed in this study that permitted repeated 'pogostick' penetrations without raising the instrument to the surface. Six profiles with a total of 112 penetrations provided valuable data on the nature of hydrothermal circulation in the oceanic crust. Eleven standard heat probe stations provided some restraints on the poorly known age of the oceanic crust along the margin. Seismic reflection profiles using a 3.5 kHz system, a high resolution pulser profiler, and a large airgun were used as aids in the interpretation of the seismic and heat flow data.

The Arctic Dredge, a Benthic Biological Sampler for Mixed Boulder and Mud Substrates

1972 ◽  
Vol 29 (10) ◽  
pp. 1503-1505 ◽  
Author(s):  
A. H. Clarke
Keyword(s):  
Single Point ◽  
The Arctic ◽  
Labrador Sea ◽  
Baffin Bay ◽  
Reliable Tool ◽  
Specimen Retrieval

Benthic biological dredges of a new design have been used successfully on ice-rafted archibenthal and abyssal sediments of boulders and mud. The dredge is kite-shaped, of massive construction, and features a single point for cable attachment and a removable cannister for specimen retrieval. Experience in Baffin Bay, the Labrador Sea, and the Icelandic Shelf indicates that the arctic dredge is a reliable tool for arctic and subarctic research.

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