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Canada ratified the United Nations Convention on the Law of the Sea (UNCLOS) in 2003. With that ratification is an obligation to submit data and information to the U.N. pertaining to the limits of the country's extended continental shelf (ECS); the portion of the juridical continental shelf that extends beyond 200 nautical miles. A team of Canadian scientists, managers, and legal experts that included representation from three Federal Departments (Natural Resources Canada, Fisheries and Oceans Canada, and Global Affairs Canada) with additional support from other departments, spent 13 years compiling and acquiring data to provide the scientific evidence to support delineation of Canada's seaward most maritime limit. The submission has the potential to provide Canada with 2.4 million km (2) of additional submarine landmass in the Atlantic and the Arctic oceans over which Canada exercises sovereign rights for the purpose of exploring and exploiting its natural resources. Specific information such as the tectonic framework of the continental margin, the geomorphology of the margin and in particular the continental slope, the geologic nature of adjoined ridges, rises, and plateaux, and sediment thickness within adjacent basins are examples of fundamental pieces of geoscientific information needed to substantiate Canada's outermost maritime limits. This paper highlights a number of segments of Canada's continental margins to showcase this scientific evidence and how it is applied in the UNCLOS context. In doing so, the paper demonstrates the geologic complexity of Canada's margins as illustrated in scientific publications that have resulted from these new data collections, while at the same time presenting new scientific evidence and interpretations. This collection of data and information provides a wealth of new knowledge in Canada's offshore regions. The massive data compilation in the Atlantic led to conception of continental margins, in a source-to-sink scenario, as having an equilibrium base level or graded form, comparable to river systems. Departures from this shape relate to the interplay of sedimentary processes and in particular to those processes that do not fit the source-to-sink paradigm. For example, a significant part of the Atlantic margin is shown to be heavily influenced by along-slope geostrophic currents that generated massive contourite drift deposits. These deposits reflect lateral transport of sediment that had a significant impact on the morphology of the margin. The role of mass transport processes in shaping continental margins is also highlighted, and in particular the collapses of entire segments of the margin were observed. The prominent role mass failure processes play in delivering sediment to the adjacent abyssal plain is also critical in the ECS context. These observations challenge the entrenched notion of a continental margin comprising a shelf, slope, and rise and in particular the concept of the "continental rise". Prior to 2006, regions of the Arctic Ocean seaward of the Canadian landmass had fewer than 5000 km of seismic reflection data. The massive efforts of Arctic coastal States to map their margins for ECS purposes have led to a leap in technological advances to acquire data in ice-covered seas and have led to a wealth of new geoscientific knowledge. Perhaps foremost amongst this knowledge is demonstration that Canada Basin is indeed a fully developed ocean basin, albeit significantly infilled with sediment. Based on this knowledge and identification of related structures, new realistic tectonic scenarios for opening of the Amerasia Basin are proposed that include a significant component of transform or strike-slip motions. With seismic velocity and rock sample information, the continental nature of Alpha and Mendeleev ridges has been substantiated. Even bathymetric data were lacking in the Arctic and new editions of seafloor maps now support grids of 500 m spacing; although some regions remain sparse. Once thought to be relatively stagnant, sedimentary processes such as found in many ocean basins were discovered in the Arctic Ocean. Evidence of geostrophic currents, sediment mass failures, and deep-sea turbidity current channels were found to be ubiquitous, even in the deepest parts of the Arctic's basins. Key words: United Nations Convention on the Law of the Sea, extended continental shelf, continental margin, Atlantic Ocean, Arctic Ocean, 1. Introduction It is a common adage that we know more about the Moon and Mars than we do about the oceans on Earth. As an example, according to the [...]

[1] Three primary salt tectonic structural styles of the Scotian Basin are compared with plane strain finite element models in order to investigate their origin. Here, we focus on simplified model salt basins with initial rectangular cross-sectional geometries and follow their evolution in the context of tectonic and parametric thermal subsidence and under various sedimentation regimes. Structural style A, an open-ended roho system with a synkinematic wedge, is reproduced by models including deltaic progradation and seaward spreading/ gliding of sediments above a salt detachment. Structural style B, a linked salt tectonic system with landward regional normal faults and allochthonous salt sheets climbing seaward over Late Cretaceous and Paleogene strata, is shown to be a consequence of early aggradation followed by progradation. Structural style C is characterized by salt diapirs and intervening minibasins and is reproduced by models with Rayleigh-Taylor instabilities requiring compaction driven density inversions, weak sediments, and initial perturbations of the overburden-salt interface. Citation: Albertz, M., C. Beaumont, J. W. Shimeld, S. J. Ings, and S. Gradmann (2010), An investigation of salt tectonic structural styles in the Scotian Basin, offshore Atlantic Canada: 1. Comparison of observations with geometrically simple numerical models, Tectonics, 29, TC4017, doi: 10.1029/2009TC002539.

Borehole logs from the northern Barbados accretionary prism show that the plate-boundary decollement initiates in a low-density radiolarian claystone. With continued thrusting, the decollement zone consolidates, but in a patchy manner. The logs calibrate a three-dimensional seismic reflection image of the decollement zone and indicate which portions are of low density and enriched in fluid, and which portions have consolidated. The seismic image demonstrates that an underconsolidated patch of the decollement zone connects to a fluid-rich conduit extending down the decollement surface. Fluid migration up this conduit probably supports the open pore structure in the underconsolidated patch.

The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity–depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km2. The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity–depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity–depth profiles for each seismic trace. A thickness of 12–13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity–depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares favourably with borehole data for Miocene turbidites in the eastern Gulf of Mexico. The station-specific results also indicate that Quaternary sediments coarsen towards the Beaufort-Mackenzie and Banks Island margins in a manner that is consistent with the variable history of Laurentide Ice Sheet advance documented for these margins. Lithological factors do not fully account for the elevated velocity–depth trends that are associated with the southwestern Canada Basin and the Alpha-Mendeleev magnetic domain. Accelerated porosity reduction due to elevated palaeo-heat flow is inferred for these regions, which may be related to the underlying crustal types or possibly volcanic intrusion of the sedimentary succession. Beyond exploring the variation of an important physical property in the Arctic Ocean basin, this study provides comparative reference for global studies of seismic velocity, burial history, sedimentary compaction, seismic inversion and overpressure prediction, particularly in mudrock-dominated successions. [ABSTRACT FROM AUTHOR]

Interpretations of the Late Cretaceous to Quaternary geological history of the North American Basin rely on a seismic and lithostratigraphic framework developed predominantly from data along the northeastern United States margin. Prior to this study, attempts to extend this framework northward to the Nova Scotia margin were hindered by correlation issues across seamounts, limitations in data coverage, and significant complications caused by widespread canyon erosion and shallow salt structures. These challenges are overcome using modern seismic reflection data along the southwestern Nova Scotia margin, in the Shelburne sub-basin, where Upper Cretaceous through Quaternary sequences manifest four distinct phases in the interplay between down-slope and along-slope depositional and erosional processes. The first phase, spanning the Late Cretaceous to Late Eocene, is characterized by widespread periods of gully erosion interspersed with periods of pelagic and hemipelagic, carbonate-rich sedimentation. Extensive failure of upper slope regions related to the Montagnais meteorite impact also occurred during this time. The second phase, spanning the Oligocene to Late Miocene, is dominated by widespread erosion, deposition by gravity flow processes, and sediment re-working by bottom currents. Marked erosion and/or non-deposition along the mid-to lower slope is attributed both to down-slope and along-slope processes. The third phase, spanning the Late Miocene to Late Pliocene, is dominated by bottom current deposition including stacked sequences of giant sediment waves and large contourite drifts along the slope. The final phase, from the Late Pliocene to present, exhibits a return to predominance of down-slope gravity flows with deposition focused below the upper slope. This four phase history of depositional and erosional processes is similar to that documented south of the study area along the U.S. margin. [ABSTRACT FROM AUTHOR]

The modified Hele-Shaw cell lets us simulate sedimentation in a wide variety of situations from a river bed to a sedimentary basin. It illustrates deposition and erosion, stratigraphy, progradation, aggradation, and the origin of sedimentary structures such as beds, laminations, ripples and slumps. Using a narrow acrylic tank based on the Hele-Shaw cell, sediment and water are added at one end and water is withdrawn at the other. As observers watch sedimentary processes in real-time, sediments build up in layers in the tank, demonstrating the nature of strata as a geological record. This engaging experiment is suitable for primary to university education. It has principally been used to teach the fundamentals, but can also be used by advanced students to experiment with other sediment-water interactions such as groundwater flow and angle of repose. [ABSTRACT FROM AUTHOR]

In this study, we examine, using seismic data in conjunction with numerical modeling, a regional-scale salt detachment and associated synkinematic sediments from the Scotian margin, offshore eastern Canada. This part of the Scotian margin is characterized by an up to 4.5-km (2.8-mi)-thick and approximately 175-km (108-mi)-long synkinematic wedge of Jurassic sediments with internal sigmoidal, landward-dipping reflectors. The synkinematic wedge is laterally extensive, encompassing an area of approximately 30,000 km² (11,600 mi²), and soles into an interpreted salt detachment. The Jurassic synkinematic wedge, which is interpreted to have formed as an open-ended allochthonous salt nappe, was loaded by prograding sediments during the Jurassic. This loading squeezed the salt seaward and caused the overlying sediments to undergo extension and gravity spreading and gliding, detaching on the salt sheet. The open-ended nappe model provides a mechanism for producing a large amount of extension with very little compensating contraction. Numerical model results indicate that high rates of extension, detaching on even a thin salt layer, can result in similar sigmoidal, landward-dipping strata. Based on the numerical modeling and seismic interpretation results, we propose a new conceptual model for the Jurassic-Paleogene structural evolution of the study area; this model may also have implications for other passive-margin salt basins with regional salt detachments. [ABSTRACT FROM AUTHOR]

Detailed interpretation of 2D and 3D seismic data from the Sable Subbasin (continental margin of eastern Canada) has revealed an extensive polygonal fault system affecting Upper Cretaceous chalk of the Wyandot Formation (the Wyandot Chalk) and Cenozoic mudrocks of the Banquereau Formation. This paper offers the first detailed study of a basin-scale polygonal fault system affecting a chalk-dominated unit. The Wyandot Chalk is up to 300m thick and pervasively deformed by small-scale faults that are morphologically and quantitatively similar to those previously described from polygonal fault systems observed in mudrocks of the North Sea, and elsewhere. This suggests that they may have formed due to a common mechanism. The data presented in this paper point towards a lithological control upon the development of the polygonal fault system and argue that the syneresis hypothesis posed by Cartwright and Dewhurst [Geol. Soc. Am. Bull. 110 (1998) 1242] best explains the distribution and initiation of the analysed fault system.3D seismic attribute maps reveal an orthogonal intersection relationship between polygonal faults and tectonic faults in the study area. This relationship is interpreted to indicate that local stress perturbations around the tectonic faults influenced the propagation of the polygonal faults. [Copyright &y& Elsevier]

The Jeanne d'Arc Basin is a relatively small passive-margin rift basin that underlies what is now the northeastern corner of the Grand Banks of Newfoundland. In the Late Cretaceous and early Paleogene, the basin formed an elongated depression where sediment accumulated in and along the margins of a shallow-shelf sea. Seismic and well data were used to examine the Late Cretaceous and Paleogene evolution of the basin and to formally revise the existing stratigraphic classification scheme. In the Late Cretaceous, the western margin of the basin was characterized by a well-developed shelf and slope system comprised of the sand-prone Otter Bay and Fox Harbour members and the distally equivalent shale-prone Red Island and Bay Bulls members, respectively. These members record two main progradational episodes that are separated by a regional unconformity and a thick shale interval corresponding to the Bay Bulls Member. East of the shelf-slope system, Upper Cretaceous shale and sparse sandstone of the Dawson Canyon Formation and chalk of the Petrel Member and Wyandot Formation were deposited in a relatively condensed section. In the early part of the Paleogene, two main sandstone units, herein named the Avondale and South Mara members, were deposited east of the well-developed latest Cretaceous slope in the lower part of the Banquereau Formation. The Avondale Member corresponds to small sand-prone submarine fans deposited on the basin floor in the early Paleocene. The submarine fans were fed primarily by two canyons that incised the western margin of the basin, eroding the Late Cretaceous shelf and slope. Also in the Paleocene, siliceous shale and siltstone of the Tilton Member were deposited above bathymetric highs along the western... [ABSTRACT FROM AUTHOR]

Two wide-angle seismic reflection/refraction profiles were acquired to determine the velocity characteristics of the Meguma terrane and adjacent Avalonia northeast of the Cobequid-Chedabucto Fault Zone (CCFZ) in eastern Canada. Line 99–1 is located along the Scotian margin whereas line 99–2 crosses the Scotian margin and onshore Nova Scotia and extends into the Gulf of St. Lawrence. Velocity models were derived by forward modelling of travel times. P-wave velocities of 5.5–6.0 km/s and 6.0–6.4 km/s are interpreted to be metasedimentary rocks of the Goldenville and Halifax groups and granitic rocks, respectively. This inference is based on comparison with laboratory velocities of a suite of rock samples, offshore sampling, links to onshore geology with multibeam bathymetry, and gravity modelling. On both lines a low velocity zone (LVZ) >350 km wide and up to 15 km thick is present at mid-crustal levels. The LVZ is not observed beneath onshore Nova Scotia or northeast of Orpheus Graben, the offshore extension of the CCFZ. The crustal thickness of the Meguma terrane varies between 31 and 38 km; in contrast, the Moho is at a depth of 41 km beneath Avalonia. The velocity of the lower crust on line 99–2 is 6.8–7.1 km/s beneath the LVZ and Avalonia, and 6.6 km/s beneath onshore Meguma terrane. Poisson's ratios calculated from P- and S-wave velocities are 0.19–0.23 in the Meguma terrane crust; in contrast, Poisson's ratios of 0.24–0.25 are indicated for Avalonian crust. • Seismic reflection/refraction, gravity, and rock density/velocity data were obtained. • Two velocity/depth models were generated onshore and offshore of Nova Scotia, Canada. • Both models show an extensive low-velocity zone in the offshore Meguma terrane. • Meguma terrane has crustal structure different from that of adjacent Avalonia. • Avalonia extends only 30 km under Meguma terrane in faulted contact. [ABSTRACT FROM AUTHOR]

Hydrocarbons occur in two regional, Upper Cretaceous limestone units—the Turonian-Coniacian Petrel Member, and the Santonian-Maastrichtian Wyandot Formation. The units form important seismic markers beneath the Scotian Shelf and the Grand Banks of Eastern Canada. They mainly consist of bioturbated chalk and minor amounts of calcareous mudstone. A search for source rock using the Δ log R technique showed intervals with source potential, but testing of core and cuttings by Rock-Eval analysis showed no source potential. Three issues are the main cause for the inconsistency: (1) unconsolidated shales that likely included organic material were lost during sample washing; (2) severe contamination by mud additives; and (3) presence of gas. The organic matter found on the shelf has been strongly oxidised, but the distal facies of these limestone units and condensed shale units above and below may yet have potential to form source rock, beyond the studied areas. [Copyright &y& Elsevier]