The Morphology of Two Transverse Channels on the Northeast Newfoundland Shelf

Warren, John S.

doi:10.4138/1832

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…Previous studies (Warren 1976;Dale & Haworth 1979;Cumming et al 1992;Shaw et al 1999) reveal the typical seismo-stratigraphic succession on the western part of the shelf as: (i) bedrock; (ii) acoustically incoherent glacial diamicton (till); (iii) acoustically stratified glaciomarine mud; (iv) acoustically transparent postglacial mud (in basins); and (v) postglacial sand and gravel (in shallow water near coasts). Deptuck et al (2007) showed that TMFs exist off Hawke Saddle, Notre Dame Trough and Trinity Trough, and that Trinity TMF was built from a series of incoherent wedges consisting of glacigenic debrisflows.…”

Section: Previous Investigationsmentioning

confidence: 99%

“…The Northeast Newfoundland Shelf differs from shelves elsewhere in Atlantic Canada on account of the relatively great depth of both the offshore banks and the troughs that dissect them. Warren (1976) divided the shelf (Fig. 1) into four physiographical regions: (i) the shallow (<200 m depth) inner shelf; (ii) outer shelf banks with depths between 200 and 400 m, namely Hamilton Bank, Belle Isle Bank and Funk Island Bank; (iii) the marginal channel separating the inner shelf from the banks; and (iv) shelf-crossing troughs.…”

Section: Study Areamentioning

confidence: 99%

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Glacial geomorphology of the Northeast Newfoundland Shelf: ice‐stream switching and widespread glaciotectonics

Shaw

Longva

2017

Boreas

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Analysis of Olex bathymetry, multibeam sonar and seismic survey data, shows that, perhaps during the mid Pleistocene, grounded ice crossing the Northeast Newfoundland Shelf was topographically steered in Hawke Saddle, occupied a broad trough underlying much of Belle Isle Bank and present‐day Notre Dame Trough, and deposited ~100 m of stacked glacigenic sediment; grounded ice crossed southern Funk Island Bank and occupied Notre Dame Trough. During the Wisconsinan Stage, c. 30 cal. ka BP, flow remained topographically steered in Hawke Saddle, but due to flow switching two convergent ice streams incised the stacked sediments of the earlier phase, creating the modern Notre Dame Trough, and diverging around an erosional remnant near the shelf edge. The ice margin at the Last Glacial Maximum (c. 18 14C ka BP) was at the shelf edge in Trinity Trough but far to the west elsewhere. Retreating ice did not stabilize at fjord mouths, but halted several times within fjords. Shelf morphology was shaped by glaciotectonism. The large tectonized zone on the north flank of Notre Dame Trough was created by the northernmost of the two convergent streams. Glaciotectonism was most widespread in the enclosed St. Anthony Basin, where the Quaternary cover has been stripped away, arrays of composite ridges have formed and sediment blocks have been thrust onto the adjacent bank. A large hill‐hole pair was formed on the east side of the basin, extending onto Belle Isle Bank. A hill‐hole pair on the inner shelf was formed by ice flow from the northwest into Notre Dame Channel. Evidence of widespread glaciotectonism distinguishes this relatively deep shelf from the adjoining, relatively shallow, eastern Canadian shelves, but has strong parallels with parts of the Norwegian continental shelf where methane hydrates maybe played a role in regulating ice‐stream flow.

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Section: Previous Investigationsmentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Glacial geomorphology of the Northeast Newfoundland Shelf: ice‐stream switching and widespread glaciotectonics

Shaw

Longva

2017

Boreas

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“…Trinity Trough and Notre Dame Channel (Fig. 1) (Warren, 1976) extend to the shelf edge. Farther north, on the Labrador Shelf, deep troughs (Figs.…”

Section: The Continental Shelves In the Study Areamentioning

confidence: 99%

Palaeogeography of Atlantic Canadian continental shelves from the last glacial maximum to the present, with an emphasis on Flemish Cap

Shaw¹

2006

J. Northw. Atl. Fish. Sci.

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Flemish Cap is a fragment of continental crust detached from related terranes in Europe and Ireland by crustal spreading and stretching over the last 150 Ma. It has a core of basement rocks (chiefly Hadrynian granite) surrounded by younger sedimentary rocks. Since the last glacial maximum the geography of the surrounding shelves has changed due to glacial eustatic and isostatic processes. Glacier ice reached the edge of the continental shelves in most areas at its maximum extent. The ice retreated by calving in deeper water, with accelerated calving of the Gulf of St. Lawrence beginning just before 14 ka BP (radiocarbon years). By 13 ka BP ice was largely confined to land areas. An archipelago on the outer shelf, from Grand Bank to the continent, persisted from >13 ka BP until c. 8 ka BP. Flemish Cap was probably not glaciated, although it was-and continues to be-impacted by icebergs. It was probably not emergent, although it was impacted by high wave energy during sealevel lowering. In comparison with the more 'hostile' glacial and ice-proximal environments along the shelf edge from southern Labrador to New England Flemish Cap was a relatively benign shallow-water environment with hard substrates, and may be a suitable candidate for a glacial marine refugium.

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“…The Laurentian Channel is more than 500 m deep in some areas, and shallows at the shelf edge to a depth of 410 m. Off the northeast coast of Newfoundland, the continental shelf and the offshore banks (Funk Island Bank, 220-300 m) are deeper than elsewhere. Trinity Trough and Notre Dame Channel (Warren, 1976) extend to the shelf edge. Off Nova Scotia, Emerald Basin and LaHave Basin are the largest of a series of irregular basins on the shelf.…”

Section: Study Areamentioning

confidence: 99%

Geomorphic Evidence of Postglacial Terrestrial Environments on Atlantic Canadian Continental Shelves

Shaw

2007

gpq

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Changes in the geography of Atlantic Canada since the last glacial maximum (LGM) are grouped into three phases. The first phase (LGM – ca. 13 ka BP) commences with glaciers at the edge of the continental shelves, and ends with the glaciers having retreated to near modern coasts. In the second phase (ca. 13 ka BP‑10 ka BP), glaciers were mainly on land; on the continental shelves there were scattered small ice caps and an outer-shelf archipelago. Early in phase three, beginning ca. 10 ka BP, glaciers were largely absent, and the archipelago was gradually submerging; elsewhere, falling relative sea levels caused emergence. Multibeam sonar mapping has revealed the geomorphic evidence of submerged terrestrial environments of phases II and III, including fluvial, deltaic, and coastal systems. The best-preserved fluvial systems are in Northumberland Strait and the Bras d’Or Lakes. Elsewhere, multibeam bathymetric data allow discrimination between fluvial and non-fluvial channels. Deltas were mainly preserved in the special circumstances of Newfoundland fjords. Submerged coastal systems are common in the Bras d’Or Lakes, but rare elsewhere. Landscape preservation is ascribed to special circumstances. Paleogeographic reconstructions have applications in the field of evolutionary biology and archaeology.Les changements de la géographie du Canada atlantique depuis le dernier maximum glaciaire (DMG) sont regroupés en trois phases. La première (DMG, environ 13 ka avant le présent) débute au moment où les glaciers occupent le rebord des plates-formes continentales et se termine lorsqu’ils ont reculé jusqu’à proximité des lignes de rivage contemporaines. Pendant la deuxième phase (de 13 ka à 10 ka avant le présent), les glaciers se trouvaient principalement sur les terres; il y avait de petites calottes glaciaires éparses sur les plates-formes continentales et un archipel sur la partie extérieure des plates-formes. Au début de la troisième phase, il y a environ 10 000 ans, les glaciers étaient en grande partie absents et l’archipel s’enfonçait progressivement dans les eaux; ailleurs, les niveaux relatifs de la mer, alors à la baisse, engendraient une émergence des terres. La bathymétrie au sonar a révélé des indices géomorphologiques de milieux terrestres submergés pendant les phases II et III, incluant des systèmes fluviaux, deltaïques et côtiers. Les systèmes fluviaux les mieux conservés se situent dans le détroit de Northumberland et les lacs Bras d’Or. Ailleurs, les données bathymétriques permettent de distinguer des chenaux fluviaux d’autres chenaux non fluviaux. Les deltas ont été principalement conservés dans les cas particuliers que constituent les fjords de Terre-Neuve. Les systèmes côtiers submergés sont communs dans les lacs Bras d’Or, mais rares ailleurs. La préservation de ces paysages dépend de circonstances spéciales. Ces reconstitutions paléogéographiques ont des applications dans les domaines de la biologie évolutive et de l’archéologie

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The Morphology of Two Transverse Channels on the Northeast Newfoundland Shelf

Cited by 4 publications

References 9 publications

Glacial geomorphology of the Northeast Newfoundland Shelf: ice‐stream switching and widespread glaciotectonics

Glacial geomorphology of the Northeast Newfoundland Shelf: ice‐stream switching and widespread glaciotectonics

Palaeogeography of Atlantic Canadian continental shelves from the last glacial maximum to the present, with an emphasis on Flemish Cap

Geomorphic Evidence of Postglacial Terrestrial Environments on Atlantic Canadian Continental Shelves

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