On the Submarine Geomorphology Along the East Coast of Baffin Island

1971 ◽  
Vol 8 (2) ◽  
pp. 185-195 ◽  
Author(s):  
O. H. Løken ◽  
D. A. Hodgson
Keyword(s):  
Continental Shelf ◽  
Continental Slope ◽  
East Coast ◽  
Unknown Origin ◽  
Baffin Island ◽  
Baffin Bay ◽  
Reconnaissance Survey ◽  
Bathymetric Map ◽  
Distinct Features ◽  
Island Coast

A reconnaissance survey was made of the submarine geomorphology along the east coast of Baffin Island using an echo sounder. The survey focused on: (1) the continental slope, (2) the continental shelf, and (3) the fiords. The depth contours on the continental slope are roughly parallel to the coastline. The overall steepness of the slope is typically 2–3°, with the steeper sections near the top. Small irregularities of unknown origin are commonly found in the slope profiles.Transverse troughs with depths of almost 900 m are the most distinct features of the 30–50 km-wide continental shelf. The larger channels are associated with major fiord–valley systems on the island. Ridges, interpreted as lateral moraines, extend along the trough margins. Marginal channels commonly found along glaciated coasts appear to be absent from this section of the Baffin Island coast, but subbottom profiles are not yet available.The fiords of east Baffin Island show the typical fiord characteristics and reach a maximum depth of 900 m. The deepest part is usually below the highest mountains along the fiord. All fiords continue into offshore channels of varying depth.Many significant changes to the bathymetric map of the west side of Baffin Bay have been made. This is partly due to the survey plan and partly to the greatly improved plotting charts which were used.

scholarly journals Land to Ocean Transfer of Erosion-Related Organic Carbon, Waipaoa Sedimentary System, East Coast, New Zealand

2021 ◽  
Author(s):  
◽  
Hannah Lema Brackley
Keyword(s):  
New Zealand ◽  
Organic Carbon ◽  
Continental Shelf ◽  
Continental Slope ◽  
East Coast ◽  
Thick Layer ◽  
Terrestrial Source ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Floodplain Sediments

<p>Mountainous islands of the Pacific Rim (such as New Zealand) purportedly deliver up to 40% of the suspended sediment load and up to 35% of the riverine particulate organic carbon (POC) load to the world's oceans. On the east coast of New Zealand's North Island, the Waipaoa River drains a steep, 2205 km2 catchment located on the active collisional East Coast Continental Margin. It has an annual suspended sediment load of 15 Tg (15 x 1012 g), making up ~7% of New Zealand's total yield to the Pacific Ocean, and a mean annual POC discharge to the Pacific Ocean of 86.7 Gg (86.7 x 109 g). The annual loss of OC to the floodplain is ~9% of this annual POC discharge (~7.8 Gg). A range of analyses (including organic carbon content (%OC), stable carbon isotopes (Delta 13C), radiocarbon (14C), carbon to nitrogen ratios (C/N)a and carbon loadings (OC:SA)) were performed on correlative sediments from a transect of 7 cores from depositional sites located on the Waipaoa River floodplain and adjacent continental shelf and slope. Results were used to determine biogeochemical characteristics of organic carbon (OC) at a range of depositional sites during its transfer from terrestrial source to marine sink, and how large floods impact OC transfer to the marine environment. The high temporal variability in OC content (0.2 to 3.5%) and different source signatures (Delta 13C of -26.7 to -20.6% degrees) of Waipaoa River floodplain deposits prevented the establishment of a clear benchmark signature for flood deposits that may be recognisable in the marine sedimentary record. The high spatial and temporal variability of floodplain sediment OC, combined with the areal extent of floodplains within the catchment, indicates the appreciable modulating effect the floodplain has on OC transfers to the ocean. Since extensive stopbanks were constructed on the main floodplain since the 1940' s, sequestration of OC in floodplain sediments has reduced by about half, increasing the overall efficiency of the Waipaoa River in transferring terrestrial OC directly to the marine environment.  Flood layers are preserved in the marine sedimentary record. Continental shelf sediments indicate that during Cyclone Bola (March 1988, a rainfall event with a >100 year return period), the extreme river discharge produced a hyperpycnal (negatively buoyant) plume, preserved as a ~10 cm thick layer on the inner shelf and a ~1 cm thick layer on the mid-shelf. The flood layer contains a significant amount of terrestrially-sourced OC (up to 86% of total OC in >25 Mu m fraction) which subsequently was rapidly buried by normal marine deposits (in which ~60% of OC in >25 Mu m fraction is terrestrial), thereby preserving its strong terrestrial source signature. As sediments are physically and biologically processed at various depositional sites across the continental shelf and slope, they lose some of their modern terrestrial OC, and the concurrent addition of marine sourced OC results in the sediments gaining a stronger marine biogeochemical signature (Delta 13C values increasing from -26.2% degrees for floodplain sediments to -21.6% degrees for upper continental slope sediments). Carbon loading (OC:SA) and 14C data revealed the contributions of kerogen, modern terrestrial OC and modern marine OC to the total OC of continental shelf and slope surface sediments. Sediments retain about 40% of their terrestrial OC following transport to the continental slope, of which a significant amount consists of kerogen. Because of high erosion rates within the catchment, kerogen associated with the particles escapes oxidation, and therefore makes up a large part of the POC flux. Kerogen is preserved across the margin to the mid-slope, where only 8% of the bulk sediment OC consists of modern terrestrial OC, 58% is modern marine OC and 34% is kerogen. Biomarker analyses of surface samples also support findings that terrestrial OC is being transferred across the continental margin, with plant sterols, long chain alcohols and long chain fatty acids (biomarkers indicative of vascular plants) persisting as far offshore as the mid-continental slope. Results presented verify and add to the understanding of OC transfers and transformations at a range of depositional sites from terrestrial source to marine sink. This study provides the first quantitative assessment of land to ocean OC transfers from New Zealand. These findings, together with information on sediment budgets and depositional rates of OC in terrestrial and marine depositional environments, could provide a vital step toward establishing global OC budgets for small mountainous island environments.</p>

The Broughton Trough on the continental shelf of eastern Baffin Island, Northwest Territories

1982 ◽  
Vol 19 (8) ◽  
pp. 1599-1607 ◽  
Author(s):  
R. Gilbert
Keyword(s):  
Continental Shelf ◽  
River System ◽  
Distal Region ◽  
Baffin Island ◽  
Relative Level ◽  
Seismic Surveys ◽  
Baffin Bay ◽  
Second Stage ◽  
Marine Sedimentation ◽  
Third Stage

Bathymetric and seismic surveys of the trough across the continental shelf of Baffin Island at Broughton Island indicate that there were four stages in its development. The first involved deposition of Cretaceous and early Tertiary marine sediments before and during formation of a graben associated with the opening of Baffin Bay. With the uplift of Baffin Island, extensive deltaic deposits at the distal end of the trough were laid down in the second stage. These deposits are thought to represent the products of a river system raised much above grade, flowing in the trough and the fiords to the southwest, and depositing in a sea with a relative level 300–400 m below present. In the third stage during Pliocene–Pleistocene glaciation, the proximal regions of the trough were eroded to more than 700 m below present sea level. Lateral moraines indicate the extension of ice to the edge of the continental shelf, although the relatively small amount of erosion in the distal region suggests that the ice may have been partially floating. Glaciomarine and marine sedimentation following glaciation is the final stage in the evolution of the trough.

Late Quaternary paleoceanography of the western Baffin Bay region: evidence from fossil diatoms

1990 ◽  
Vol 27 (11) ◽  
pp. 1487-1494 ◽  
Author(s):  
Kerstin M. Williams
Keyword(s):  
Sea Ice ◽  
East Coast ◽  
Late Quaternary ◽  
Baffin Island ◽  
Ocean Water ◽  
Sea Ice Extent ◽  
Baffin Bay ◽  
Oceanographic Variables ◽  
Diatom Productivity ◽  
Fossil Diatoms

Seven marine cores from the east coast of Baffin Island were examined for variations in diatom content. The cores have good age control and were used for Holocene paleoceanographic reconstruction. A diatom barren zone or a zone of much reduced diatom productivity is evident some time during the early to middle Holocene. This zone ends earlier in the southern area than farther north. The changes in diatom productivity may be caused by changing oceanographic variables such as sea ice extent and the presence of a meltwater cap during deglaciation. Light isotope 18O events ("meltwater spikes") generally coincide with barren or reduced productivity zones in the cores from the middle and southern part of the shelf and from Jones Sound, suggesting a general surficial cooling of the fjord and ocean water. If diatom productivity was depressed because of a meltwater cap over the core sites with increasing sea ice extent, the theory of a general "marine optimum" in all of Baffin Bay and Davis Strait from 8000 to 6000 BP may have to be modified.

Latest Quaternary and Holocene paleoceanography of the eastern Baffin Island continental shelf, Canada: benthic foraminiferal evidence

1989 ◽  
Vol 26 (11) ◽  
pp. 2236-2248 ◽  
Author(s):  
Lisa E. Osterman ◽  
Alan R. Nelson
Keyword(s):  
Continental Shelf ◽  
The Arctic ◽  
Baffin Island ◽  
The South ◽  
Baffin Bay ◽  
The North ◽  
Postglacial History ◽  
Foraminiferal Species ◽  
Organic Sediment ◽  
Shelf Sediments

Foraminiferal zones, radiocarbon ages on shells, and corrected ages on pretreated organic sediment from four cores from the eastern Baffin Island continental shelf suggest a three-stage deglacial to postglacial history (Late Wisconsin to Holocene). The earliest sediments in the cores contain foraminiferal species (Elphidium excavatum, Cassidulina reniforme, Islandiella helenae) indicative of distal glaciomarine environments that lasted at least several thousand years. An oceanographic change about 8500 years ago is indicated by a Melonis zaandamae zone in northern and central shelf cores collected from 200–800 m water depth. The presence of M. zaandamae in the north and its absence in the south suggest warmer and more saline postglacial water in northern Baffin Bay, whose influence became diluted with cooler coastal meltwater as the current flowed south along the Baffin Island Shelf. Sediments after 6000 years ago on the northern and central shelf are dominated by agglutinated foraminifera, suggesting dissolution of calcareous species. This dissolution event, which affected deeper water cores sooner than cores from the shelf, may be related to the influx of cold, CO2-rich water from the Arctic Ocean during the mid-Holocene. Thus, postglacial oceanographic changes in Baffin Bay appear first in deep northern waters; the lag time in the response to these changes in the shallower water on the shelf and to the south may have been as long as several thousand years.

Rare Skates of the Newfoundland and Neighbouring Areas

1965 ◽  
Vol 22 (2) ◽  
pp. 259-279 ◽  
Author(s):  
Wilfred Templeman
Keyword(s):  
Continental Slope ◽  
East Coast ◽  
First Record ◽  
Baffin Island ◽  
Body Proportions ◽  
Scotian Shelf ◽  
Raja Erinacea ◽  
Previous Record ◽  
West Greenland ◽  
Nova Scotian

Raja erinacea is reported from the east coast of Newfoundland, a first record from the Newfoundland area. Raja hyperborea is recorded from east of Baffin Island, 60 nautical miles south of the most southerly previous record on this coast. Raja jenseni and Raja mollis have been found on the southwest slope of the Grand Bank, and Raja mollis on the continental slope off northeast Newfoundland and Baffin Island. These are northward and eastward extensions of range from the southern part of the Nova Scotian Shelf. Two individuals of Raja lintea are recorded from Flemish Cap, the first record of this species west and south of West Greenland. Body proportions and other characteristics of the rare skates are discussed in relation to those reported by previous authors.

scholarly journals Land to Ocean Transfer of Erosion-Related Organic Carbon, Waipaoa Sedimentary System, East Coast, New Zealand

2021 ◽  
Author(s):  
◽  
Hannah Lema Brackley
Keyword(s):  
New Zealand ◽  
Organic Carbon ◽  
Continental Shelf ◽  
Continental Slope ◽  
East Coast ◽  
Thick Layer ◽  
Terrestrial Source ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Floodplain Sediments

<p>Mountainous islands of the Pacific Rim (such as New Zealand) purportedly deliver up to 40% of the suspended sediment load and up to 35% of the riverine particulate organic carbon (POC) load to the world's oceans. On the east coast of New Zealand's North Island, the Waipaoa River drains a steep, 2205 km2 catchment located on the active collisional East Coast Continental Margin. It has an annual suspended sediment load of 15 Tg (15 x 1012 g), making up ~7% of New Zealand's total yield to the Pacific Ocean, and a mean annual POC discharge to the Pacific Ocean of 86.7 Gg (86.7 x 109 g). The annual loss of OC to the floodplain is ~9% of this annual POC discharge (~7.8 Gg). A range of analyses (including organic carbon content (%OC), stable carbon isotopes (Delta 13C), radiocarbon (14C), carbon to nitrogen ratios (C/N)a and carbon loadings (OC:SA)) were performed on correlative sediments from a transect of 7 cores from depositional sites located on the Waipaoa River floodplain and adjacent continental shelf and slope. Results were used to determine biogeochemical characteristics of organic carbon (OC) at a range of depositional sites during its transfer from terrestrial source to marine sink, and how large floods impact OC transfer to the marine environment. The high temporal variability in OC content (0.2 to 3.5%) and different source signatures (Delta 13C of -26.7 to -20.6% degrees) of Waipaoa River floodplain deposits prevented the establishment of a clear benchmark signature for flood deposits that may be recognisable in the marine sedimentary record. The high spatial and temporal variability of floodplain sediment OC, combined with the areal extent of floodplains within the catchment, indicates the appreciable modulating effect the floodplain has on OC transfers to the ocean. Since extensive stopbanks were constructed on the main floodplain since the 1940' s, sequestration of OC in floodplain sediments has reduced by about half, increasing the overall efficiency of the Waipaoa River in transferring terrestrial OC directly to the marine environment.  Flood layers are preserved in the marine sedimentary record. Continental shelf sediments indicate that during Cyclone Bola (March 1988, a rainfall event with a >100 year return period), the extreme river discharge produced a hyperpycnal (negatively buoyant) plume, preserved as a ~10 cm thick layer on the inner shelf and a ~1 cm thick layer on the mid-shelf. The flood layer contains a significant amount of terrestrially-sourced OC (up to 86% of total OC in >25 Mu m fraction) which subsequently was rapidly buried by normal marine deposits (in which ~60% of OC in >25 Mu m fraction is terrestrial), thereby preserving its strong terrestrial source signature. As sediments are physically and biologically processed at various depositional sites across the continental shelf and slope, they lose some of their modern terrestrial OC, and the concurrent addition of marine sourced OC results in the sediments gaining a stronger marine biogeochemical signature (Delta 13C values increasing from -26.2% degrees for floodplain sediments to -21.6% degrees for upper continental slope sediments). Carbon loading (OC:SA) and 14C data revealed the contributions of kerogen, modern terrestrial OC and modern marine OC to the total OC of continental shelf and slope surface sediments. Sediments retain about 40% of their terrestrial OC following transport to the continental slope, of which a significant amount consists of kerogen. Because of high erosion rates within the catchment, kerogen associated with the particles escapes oxidation, and therefore makes up a large part of the POC flux. Kerogen is preserved across the margin to the mid-slope, where only 8% of the bulk sediment OC consists of modern terrestrial OC, 58% is modern marine OC and 34% is kerogen. Biomarker analyses of surface samples also support findings that terrestrial OC is being transferred across the continental margin, with plant sterols, long chain alcohols and long chain fatty acids (biomarkers indicative of vascular plants) persisting as far offshore as the mid-continental slope. Results presented verify and add to the understanding of OC transfers and transformations at a range of depositional sites from terrestrial source to marine sink. This study provides the first quantitative assessment of land to ocean OC transfers from New Zealand. These findings, together with information on sediment budgets and depositional rates of OC in terrestrial and marine depositional environments, could provide a vital step toward establishing global OC budgets for small mountainous island environments.</p>

The Recent Cypraeidae of Northern New Zealand from the Kermadec Islands to the Poor Knights Islands, Southwest Pacific Ocean (Mollusca: Gastropoda: Cypraeidae)

The Festivus ◽  
2018 ◽  
Vol 50 (1) ◽  
pp. 36-54
Author(s):  
John Daughenbaugh
Keyword(s):  
New Zealand ◽  
Pacific Ocean ◽  
Continental Shelf ◽  
East Coast ◽  
Species Distributions ◽  
East Side ◽  
Tropical Eastern Pacific ◽  
The North ◽  
The Poor ◽  
Coastal Shelf

For researchers, isolated regions at the periphery of species’ distributions hold a peculiar fascination. The causes of their remoteness vary based on: distance (e.g. the Tropical Eastern Pacific), distance and countervailing currents (e.g. the Marquesas), location in a present day gyre (e.g. the Pitcairn Group) or the absence of present day means of veliger transport (e.g. the Vema Seamount). (Daughenbaugh & Beals 2013; Daughenbaugh 2015a & b, 2017). The northern New Zealand Region from the Kermadec Islands (Kermadecs) to the coastal and shelf areas in the northernmost part of New Zealand’s North Island (Northland), including the Poor Knights Islands (PKI), constitute the distributional boundaries for a number of Cypraeidae species. The boundaries are the result of the absence of coastal shelves along the east side of the Kermadec Ridge (Ridge) and precipitous drops to abyssal depths along Northland’s east coast continental shelf. Tropical waters, with their potential to transport Cypraeidae larvae, flow eastward from southern Queensland, Australia, entrained in the Tasman Front which terminates when reaching North Cape, the northernmost tip of Northland. There, the North Cape Eddy captures most of this flow while the remainder, the East Auckland Current (EAUC), flows intermittently southward along the eastern coastal, shelf and offshore areas of Northland into waters incapable of supporting Cypraeidae populations.

scholarly journals Stability of a buoyancy-driven coastal current at the shelf break

2002 ◽  
Vol 452 ◽  
pp. 97-121 ◽  
Author(s):  
C. CENEDESE ◽  
P. F. LINDEN
Keyword(s):  
Continental Shelf ◽  
Continental Slope ◽  
Unstable Mode ◽  
Shelf Break ◽  
Coastal Current ◽  
Surface Currents ◽  
Flat Bottom ◽  
Vertical Boundary ◽  
Axisymmetric Disturbances ◽  
A Current

Buoyancy-driven surface currents were generated in the laboratory by releasing buoyant fluid from a source adjacent to a vertical boundary in a rotating container. Different bottom topographies that simulate both a continental slope and a continental ridge were introduced in the container. The topography modified the flow in comparison with the at bottom case where the current grew in width and depth until it became unstable once to non-axisymmetric disturbances. However, when topography was introduced a second instability of the buoyancy-driven current was observed. The most important parameter describing the flow is the ratio of continental shelf width W to the width L* of the current at the onset of the instability. The values of L* for the first instability, and L*−W for the second instability were not influenced by the topography and were 2–6 times the Rossby radius. Thus, the parameter describing the flow can be expressed as the ratio of the width of the continental shelf to the Rossby radius. When this ratio is larger than 2–6 the second instability was observed on the current front. A continental ridge allowed the disturbance to grow to larger amplitude with formation of eddies and fronts, while a gentle continental slope reduced the growth rate and amplitude of the most unstable mode, when compared to the continental ridge topography. When present, eddies did not separate from the main current, and remained near the shelf break. On the other hand, for the largest values of the Rossby radius the first instability was suppressed and the flow was observed to remain stable. A small but significant variation was found in the wavelength of the first instability, which was smaller for a current over topography than over a flat bottom.

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