Multibeam imagery and 3.5 kHz sub-bottom profiles acquired from CCGS Amundsen between 2003 and 2013 by ArcticNet and the Ocean Mapping Group at the University of New Brunswick provide information on seafloor features, geology, bathymetry and morphology in eastern Parry Channel and the adjoining large channels in the Canadian Arctic Archipelago. Together these include Peel Sound, Barrow Strait, Lancaster Sound, Wellington Channel, Prince Regent Inlet, Admiralty Inlet and Navy Board Inlet. Those data are in part complemented by high resolution single channel seismic reflection profiles acquired by the Geological Survey of Canada in the 1970s and 1980s and by sediment cores that provide chronological and depositional information.The occurrence and pattern of streamlined mega-scale ridge and groove lineations (MSGLs) indicate that these waterways were occupied by glacial ice streams in the past. Chronological information from marine and adjoining terrestrial areas suggests a long history of glacial events ranging in time from Early Pleistocene to Late Wisconsinan. Seafloor morphology and MSGL trends together with terrestrial ice flow patterns indicate that ice streams flowed into Barrow Strait from Peel Sound and Wellington Channel, and ice streams in Prince Regent, Admiralty and Navy Board inlets flowed northward into and eastward along Lancaster Sound. Recession of the ice stream westward along Parry Channel occurred similar to 16 cal ka BP to 10.8 cal ka BR Thick ice-contact sediments deposited by a late ice advance from Prince Regent Inlet constitute the seabed across a large area of western Lancaster Sound. Timing for that late ice advance appears to be bracketed between the 11.5 cal ka BP lift-off of the eastern Parry ice stream north of Prince Leopold Island and the similar to 10.0 cal ka BP deglaciation of Prince Regent Inlet. Seafloor morphology and lineation trends suggest that ice delivered by the ice stream in Peel Sound was the westernmost tributary to the ice stream occupying Lancaster Sound during the late Wisconsinan glaciation. Bathymetric data and MSGLS indicate that the ice stream emanating from M'Clintock Channel flowed westward. (C) 2017 Elsevier Ltd. All rights reserved.

All inlets and fjords on northern Baffin Island record glacial erosion by outlet glaciers (Shepard 1931; Pelletier 1966). However, their positions were probably influenced by prior fluvial erosion (Fortier & Morley 1956; Pelletier 1966; Gilbert 1982) or by graben-style faulting (Andrews & Miller 1979; Gilbert 1982; Dowdeswell & Andrews 1985; England 1987). Navy Board Inlet is a narrow waterway (about 10 km wide) located south of Lancaster Sound between Baffin Island and Bylot Island in Arctic Canada (Fig. 1). Lineations formed by the movement of glacial ice are preserved on the seafloor of this inlet. Fig. 1. Multibeam bathymetry, cross-sections and sub-bottom profiler data over crag-and-tail features in Navy Board Inlet, Nunavut, Canada. ( a ) Sun-illuminated multibeam-bathymetric data showing crag-and-tail features. Acquisition system Kongsberg EM300. Frequency 30 kHz. Grid-cell size 10 m. ( b ) Location of study area (red box; map from IBCAO v. 3.0). ( c ) Detail of crag-and-tail features located on the margin of a bedrock high. Locations of cross-sections indicated by labelled white lines. ( d …

Multibeam sonar imagery provides evidence of depositional and erosional seafloor features emplaced by a glacial ice stream that flowed through Amundsen Gulf into the Beaufort Sea during the last glaciation. Figure 1a, c illustrate seafloor features that occur SW of Banks Island in the northwestern part of Amundsen Gulf (Fig. 1b). Water depths in this part of the axial trough range from 350 to 435 m. Prominent seafloor landforms include parallel ridges and grooves that trend northwesterly across the region. Depressions up to 135 m wide and 45 m deep occur as irregular linear and arcuate-shaped interruptions in many of the ridges. The linear interruptions extend across adjoining ridges along trends that lie approximately normal to the trend of the ridges (Fig. 1a, c). Arcuate-shaped depressions (moats) connect with wider inter-ridge valleys trending to the NW. In many instances the linear ridges, apparently undiminished in height adjacent …

The presence of streamlined glacial landforms in the submarine geological record from high-latitude fjords and channels provides evidence with which to identify the manner and direction of glacier flow and to infer subglacial processes. Numerous linear and curvilinear elongate features extending up to 15 km in length have been recognized in Peel Sound, Canadian Arctic Archipelago. These well-preserved sedimentary landforms reflect the former presence of a fast-flowing ice stream that flowed through Franklin Strait and Peel Sound. Multibeam swath-bathymetric imagery from an overdeepened region of Peel Sound near its junction with Franklin Strait, where the trend of the channel changes from NE to north (Fig. 1b, c), is shown in Figure 1a. Water depths here range from 390 to 460 m. Parallel ridge and groove bedforms form prominent seabed features on all the survey transects that …

Palaeo-ice streams existed in many marine channels of the Canadian Arctic Archipelago (e.g. Clark & Stokes 2001; Stokes et al. 2006; MacLean et al. 2010, 2015). These include Amundsen Gulf at the southwestern end of the Northwest Passage, where multibeam imagery has revealed a variety of subglacial features (Stokes et al. 2006; MacLean et al. 2012, 2015) (Fig. 1a, b). Six or more stacked ice-contact deposits in NW Amundsen Gulf indicate successive advances of a grounded ice stream from a pinning point on the rocky shallow seabed south of Banks Island. Stokes et al. (2006) also considered this to be a pinning point for the ice stream. Further evidence of the dynamic nature of glacial events in Amundsen Gulf is provided by Batchelor et al. (2014), who recognized sediment sequences deposited by eight individual Amundsen Gulf ice streams or readvances of the same ice stream in the outer gulf and on the Beaufort Shelf. Fig. 1. Multibeam sonar imagery and profile of crag-and-tail features formed subglacially in the lee of bedrock outcrops in northwestern Amundsen Gulf, Canadian Arctic Archipelago. ( a ) Location of study area (red box; map from IBCAO v. 3.0). …

Amundsen Gulf and adjoining Dolphin and Union Strait and Coronation Gulf form the southwestern end of the Northwest Passage adjacent to the Beaufort Sea. Extensive high resolution multibeam sonar imagery and sub-bottom profiles of the seabed have been acquired, primarily in Amundsen Gulf, by ArcticNet and the Ocean Mapping Group at the University of New Brunswick. These data reveal a variety of seabed landforms including mega-scale glacial ridge and groove lineations, drumlins, moraines, iceberg scours, bedrock outcrops, and discontinuous sediment deposits of variable thickness. The lineations are widespread, especially in southeastern Amundsen Gulf. They resemble modern and paleo bedforms reported from Antarctica, Svalbard, Greenland and other Canadian Arctic channels, where they have been ascribed to ice streams.

Core HU97048-007PC was recovered from the continental Labrador Sea slope at a water depth of 945?m, 250?km seaward from the mouth of Cumberland Sound, and 400?km north of Hudson Strait. Cumberland Sound is a structural trough partly floored by Cretaceous mudstones and Paleozoic carbonates. The record extends from similar to 10 to 58?ka. On-board logging revealed a complex series of lithofacies, including buff-colored detrital carbonate-rich sediments [Heinrich (H)-events] frequently bracketed by black facies. We investigate the provenance of these facies using quantitative X-ray diffraction on drill-core samples from Paleozoic and Cretaceous bedrock from the SE Baffin Island Shelf, and on the?<?2-mm sediment fraction in a transect of five cores from Cumberland Sound to the NW Labrador Sea. A sediment unmixing program was used to discriminate between sediment sources, which included dolomite-rich sediments from Baffin Bay, calcite-rich sediments from Hudson Strait and discrete sources from Cumberland Sound. Results indicated that the bulk of the sediment was derived from Cumberland Sound, but Baffin Bay contributed to sediments coeval with H-0 (Younger Dryas), whereas Hudson Strait was the source during H-events 14. Contributions from the Cretaceous outcrops within Cumberland Sound bracket H-events, thus both leading and lagging Hudson Strait-sourced H-events. Copyright (c) 2012 John Wiley & Sons, Ltd.

The study area lies within the central part of the Canadian Arctic Archipelago; a region that was covered by the Laurentide Ice Sheet during the Late Wisconsinan glaciation and earlier. Multibeam imagery from widely spaced transects indicates the presence of linear groove and ridge features on the seabed at several localities in Peel Sound, Franklin Strait, northern Larsen Sound, and within M’Clintock Channel. These lineations resemble features in Antarctica and in several formerly glaciated regions that have been interpreted to be sole marks emplaced beneath fast-flowing ice streams. Based on these analogies, a similar origin is inferred for the lineations on the channel floors within the study area The lineations are oriented parallel to the channel axes and margins. They occur on all transects within the bathymetrically deeper area at the junction of Franklin Strait and Peel Sound. Northward in Peel Sound they occur extensively on the western and central transects, and more locally on the eastern transect. Their north-south orientation is normal to that of glacial flow features on Somerset Island and most of eastern Prince of Wales Island, which border Peel Sound to the east and west, respectively. The trend of the lineations is northeasterly (parallel to the channel axis) in Franklin Strait and mainly northerly in Larsen Sound and M’Clintock Channel. Elsewhere, the seabed imagery commonly displays scours of various sizes and orientations created by the keels of icebergs. Seabed sediments revealed by 3.5kHz sub-bottom profiles are interpreted to consist primarily of ice-contact sediments, that in part are thinly mantled by draped water lain sediments. The age of the lineations has not been established. Possibly their formation was coincident with an ice stream in the M’Clintock Channel – eastern Victoria Island region, which formed an ice shelf in Viscount Melville Sound that grounded on southern Melville and Byam Martin islands at ca. 10.4–9.6 14C ka BP Alternatively, they could result from later glacial events.

Shallow geophysical and geological data acquired from 1974-1985 across a part of the northeast Baffin Island continental shelf provide information on its morphologic and stratigraphic development since the late Tertiary, culminating in the deposition of late Quaternary glacial to post-glacial sediments. The study area contains four transverse troughs, up to 36 km wide and incised up to 800 m through bedrock units of Precambrian to Tertiary age, with glacial erosion indicated by axial overdeepening (including elongate depressions at the bedrock surface, up to 180 m in relief). Bedrock units are unconformably overlain by strata up to 180 m thick, divided into six stratigraphic units to which informal names have been applied. The Cape Adair Sediments, an irregularly stratified subsurface unit with thicknesses up to 100 m, is observed beneath inter-trough areas and within Clyde and Sam Ford troughs and is tentatively correlated to the glacial to glacial marine successions of the adjacent coastal forelands of Baffin Island, which in places date back to the Pliocene. An unconformity at the surface of the Cape Adair Sediments, in places resistant to iceberg scouring, corresponds to a mainly transverse system of depressions and ridges recognised within inter-trough areas. The Scott Trough Sediments, a well-stratified subsurface unit with thicknesses up to 75 m, onlaps bedrock depressions in Scott and Buchan troughs and may record either a long period of marine deposition prior to the last glaciation, or rapid glacial marine deposition during the last deglaciation of the shelf. A conformable succession of four units that outcrop at seabed is interpreted to record a late Quaternary cycle of glacial ice-contact through glacial marine to post-glacial sedimentation. The Baffin Shelf Drift (unstratified, irregular geometry, up to 75 m thick) extends to the shelf edge and to depths of 850 m in Buchan Trough, consistent with full glacial occupation of the shelf. The unit interfingers in places with the Davis Strait Silt (stratified, mantling geometry, up to 7 m thick), which is inferred to record iceproximal to distal marine deposition during deglacial withdrawal from the shelf. A single core sample of the Davis Strait Silt comprises mud with locally derived sand and gravel, yielding no dateable material. However, downward extrapolation of radiocarbon dates in cores of overlying post-glacial muds to the top of the unit yields an age of c. 15 ka for the end of glacial conditions on the shelf. Postglacial deposition is recorded by the Tiniktartuq Mud (hemipelagic deposits in the troughs and intertrough depressions, up to 7 m thick) and the Cape Aston Sand (coarse-grained deposits =1 m thick above depths of 80-120 m). Core samples indicate both units include significant components of deposition from ice rafting and, for the Cape Aston Sand, probable reworking of glacial sediments. Grab samples from the two post-glacial units yield seabed muds and sands, consistent with ongoing deposition. Samples from the surfaces of the two glacial units yield variable textures, inferred to reflect the effects of current reworking, ice rafting and iceberg scouring. Iceberg scours (locally up to 8 m deep over glacial units) have extensively modified the seabed over most of the shelf, although abundances are reduced in inter-trough depressions and in Sam Ford and Clyde troughs. Scours extend to depths of 600 m on the upper continental slope and the outer walls of Scott and Buchan troughs. Most scours below depths of c. 300 m are inferred to be relict, whereas modern scours are recognized in shallower depths, including one observed in the process of formation in c. 90 m depth. Sediments on the floors of Scott and Buchan troughs contain a record of mass failure from the adjacent steep (up to 25°) slopes. Seepage of hydrocarbons from the seabed is also recognized on the walls of Scott and Buchan troughs, where it has resulted in indurated crusts, bacterial mats and possible pockmarks.

Airgun and high resolution Huntec seismic reflection profiles are interpreted to show up to 130 m of glacial, glaciomarine and postglacial sediments overlying bedrock. In a basin at the eastern entrance to Hudson Strait most of the surficial sediment was deposited during the last déglaciation, but in western Hudson Strait multiple till sequences from previous glaciations are recognized. Five acoustic units were identified, at least three of which were penetrated with piston cores. Foraminifera of the stratigraphically deepest core in the eastern basin indicate a proximal glaciomarine environment and a likely presence of an ice shelf. A 14C date of 8060 ± 70 yBP (TO 750) on molluscan shells gives a minimum age for the top of the acoustically laminated distal glaciomarine sediments. The early postglacial foraminifera suggest a period of increased influence of offshore bottom waters restricted to the deep eastern basin. The surface sediments of all cores contain species indigenous of colder and fresher inshore waters of the present time. The ratio of 18CV16O in the benthic foraminifer Cibicides lobatulus is herein related to bottom salinity. Downcore measurements of 8'8O on C. lobatulus tests indicate bottom paleosalinities lower by about 0.5%o shortly before the dated horizon of 8000 yBP. By this time Hudson Strait was sufficiently clear of glacial ice for establishment of the present tidal regime. The lower bottom salinities indicate that tidal mixing took place between glacial meltwater leaving Hudson Bay and the offshore counterflow. This process is thought to have reduced the sharpness of the salinity difference between the offshore water and the surface plume of Laurentide meltwater as it entered the ocean.

A molecular beam epitaxy and low temperature scanning tunneling microscopy chamber have been integrated to characterize both compound and elemental semiconductor surfaces and interfaces. The integration of these two commercially available systems has been achieved using a custom designed sample transfer mechanism. The MBE growth chamber is equipped with electron diffraction and provides substrate temperature measurements and control by means of band-edge thermometry accurate to within ±0.5°C. In addition, the microscope can operate at temperatures as low as 4K and perform ballistic electron emission microscopy measurements. The chamber that houses the microscope includes a preparation chamber with an evaporation source for metals. The entire STM chamber also rests on an active vibration isolation table, while still maintaining an all ultrahigh vacuum connection to the MBE system.

We review the literature on the occupation of Hudson Strait (800 km long by 90 km wide) by late Quaternary ice streams, and the importance of Hudson Strait as the major source for sediments associated with the North Atlantic Heinrich (H-) events. Glacial erosion of the Paleozoic outcrop on the floor of Hudson Strait and Ungava Bay resulted in the export of detrital carbonate-rich sediments to ice-proximal locations on the slope and floor of the NW Labrador Sea, mainly in meltwater and turbidite plumes, and to ice distal sites thousands of kilometres away largely as iceberg-rafted detritus (IRD). Erosion of bedrock from the Precambrian Superior and Churchill provenances of the Canadian Shield is also indicated by the isotopic analyses of sediments. The major late Quaternary H-events (H-4, H-2 and H-1) are represented in southeast Baffin Island slope sediments as detrital carbonate-rich intervals up to 40 cm in thickness and appear to represent flow along the axis of the Strait. However, the late marine isotope stage #3 event, H-3 (similar to27 ka), and a younger event (H-0, similar to11 ka), are not as dominant in the sedimentary record and probably represent a different glaciological regime with flow across Hudson Strait from eastern Ungava-Labrador. The freezing-on of sediments by supercooling in the rise from the 900 m deep Eastern Basin to the 400 m sill is proposed as the source of the abundant carbonate-rich glaciomarine sediments some 250 km from the outcrop in Eastern Basin. Sediment transport by meltwater and turbidity currents was the major process during H-events in ice-proximal settings. IRD was not a key diagnostic process at sites fronting Hudson Strait. A key feature in the instability of this ice stream might be the great depth (600 m) at the shelf break, and the deep basin, which lies seaward of the outer Hudson Strait sill.

This paper summarizes information regarding the bedrock geology underlying Hudson Strait and Ungava Bay interpreted from seismic reflection data together with shallow borehole information, published data from adjoining terrestrial areas, and from an exploratory well on Akpatok Island. Hudson Strait is underlain primarily by Lower Paleozoic sedimentary rocks (mainly calcareous carbonate rocks) that contact Precambrian metamorphic rocks of the adjacent land masses not far from the coasts of Baffin Island and Ungava and Labrador peninsulas. These sedimentary rocks also form the central platform in Ungava Bay. Younger strata, possibly of Mesozoic age occur locally in Eastern basin and their presence has also been postulated in parts of western and southwestern Hudson Strait. Three half-graben structures, downfaulted against older rocks at their southern margins, form prominent structural features in the floor of Hudson Strait. Phanerozoic (mainly Lower Paleozoic) sedimentary rocks thicken southward in these structures reaching 2000 m or more in Eastern basin. These basins have been sites for deposition of Quaternary sediments that locally reach more than 100 m in thickness. Calcareous sediments and erratics derived from glacial erosion of the Paleozoic strata are important markers in interpreting ice-flow patterns in the region and sediment dispersal seaward.

Quaternary sediments comprise five main units based on their acoustic character on high-resolution seismic profiles and sample data. These comprise ice-contact sediments, glaciomarine sequences, postglacial muds, postglacial sands and gravels, and locally in Eastern basin an acoustically unstratified unit of undetermined ice-contact or debris-flow origin. Sediment deposits, with the exception of some of the ice-contact sequences, are thickest and most complete in the basinal areas in Hudson Strait and Ungava Bay. These deposits are the main source of information regarding changing conditions, depositional and paleoceanographic environments, and chronologies in the marine areas of this region from late glacial time, through deglaciation, to more modern time. Information obtained relating to ice-margin positions, glacial-marine interactions, environments, and radiocarbon dates from fauna in cores provide a basis for correlations with the record of events in adjacent terrestrial and marine areas. In this paper the sediments, stratigraphic relationships, and late glacial-deglacial settings in each of the main basins and other relevant localities are illustrated and described, and associated chronological data are presented.

Thick, multisequence deposits of ice-contact sediments in the deep floors of Eastern and Western basins and on the seaward side of the sill at the entrance to Hudson Strait attest to the magnitude of glacial ice streams in Hudson Strait. Some of these are thought to have extended to the shelf edge and to be a source of Heinrich events in the Labrador Sea and North Atlantic Ocean. Later south-to-north ice advances across Eastern basin onto southeastern Baffin Island were less far-reaching seaward. The sediment record in the floor of Eastern basin and on its northern and northwestern flanks show that the basin was occupied by a grounded and progressively thinning ice sheet during the time of the Noble Inlet advance recognized on southeastern Baffin Island. Chronological data and similarities in the marine-terrestrial ice-sheet behaviour patterns suggest that this was one and the same ice sheet. Three potential sources for this advance are examined: Baffin Island, a Hudson Strait ice stream, and Quebec

Data from accelerator mass spectrometer radiocarbon dated sediment cores and Huntec high-resolution seismic profiles were used to investigate the age and origin of the sediments in the Eastern Basin of Hudson Strait. The data indicate that the ice-contact and glacial-marine sediments on the basin flanks and much of the upper sequence in the deep floor of the basin were produced during the Noble Inlet advance (8.9 to 8.4 ka), the last northward expansion of the Labrador Dome on to southeastern Baffin Island. On the northern flank of Eastern Basin one sequence of ice-contact sediments and glacial-marine deposits overlies bedrock; the glacial-marine sediments are transitional upslope to ice-contact sediments, and form at least two successive ice-sheet grounding zones. The earliest abundance peaks of benthic Foramininfera in glacial-marine sediments date ca. 8.6 and 8.4 ka, and correlate to sediments near the base of the 58-m-thick glacial-marine section in the deepest part of Eastern Basin. This correlation suggests that Noble inlet ice was grounded throughout Eastern Basin during the early part of its advance. In later stages the thinning ice produced grounding zones on the basin flanks while glacial-marine sediments were deposited in the deep basin. (C) 1998 John Wiley & Sons, Ltd.