Crustal structure and velocity anisotropy beneath the Beaufort Sea

Mair, J. A.; Lyons, J. A.

doi:10.1139/e81-067

Cited by 41 publications

(20 citation statements)

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“…They used stacking velocities from processing of multichannel seismic reflection data, together with a sparse compilation of seismic refraction velocities (Mair & Lyons 1981;Baggeroer & Falconer 1982), to derive measurements of interval velocity for the slope off of the Alaska margin and also a portion of the Mackenzie fan. The region studied by of the Canada Basin-exhibits the closest overall match, and the degree of correspondence is generally within or close to the uncertainty of the measurements.…”

Section: Comparisons With Published Datamentioning

confidence: 99%

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Shimeld¹,

Li²,

Chian³

et al. 2015

Geophysical Journal International

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S U M M A R YThe 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 km 2 . 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

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Section: Comparisons With Published Datamentioning

confidence: 99%

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Shimeld¹,

Li²,

Chian³

et al. 2015

Geophysical Journal International

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show abstract

“…Refraction measurements from large explosive sources were acquired from the continental rise north of Alaska by Milne (1966), and from the Canada Basin proper by Mair & Lyons (1981) and Baggeroer & Falconer (1982) (see Fig. 50.5 for location).…”

Section: Seismic Studiesmentioning

confidence: 99%

“…CANBARX lies entirely within the OCT domain, providing a sample of its upper crustal velocity structure that is not admixed with velocities from the MORB domain. A more extensive refraction array by Mair & Lyons (1981), which lies 110 km …”

Section: Contrasts In Geological and Velocity Structure Between The Mmentioning

confidence: 99%

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Chapter 50 Geology and tectonic development of the Amerasia and Canada Basins, Arctic Ocean

Grantz

Hart

Childers

2011

Memoirs

152

173

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Amerasia Basin is the product of two phases of counterclockwise rotational opening about a pole in the lower Mackenzie Valley of NW Canada. Phase 1 opening brought ocean-continent transition crust (serpentinized peridotite?) to near the seafloor of the proto-Amerasia Basin, created detachment on the Eskimo Lakes Fault Zone of the Canadian Arctic margin and thinned the continental crust between the fault zone and the proto-Amerasia Basin to the west, beginning about 195 Ma and ending prior to perhaps about 160 Ma. The symmetry of the proto-Amerasia Basin was disrupted by clockwise rotation of the Chukchi Microcontinent into the basin from an original position along the Eurasia margin about a pole near 728N, 165 W about 145.5-140 Ma. Phase 2 opening enlarged the proto-Amerasia Basin by intrusion of mid-ocean ridge basalt along its axis between about 131 and 127.5 Ma. Following intrusion of the Phase 2 crust an oceanic volcanic plateau, the Alpha-Mendeleev Ridge LIP (large igneous province), was extruded over the northern Amerasia Basin from about 127 to 89-75 Ma. Emplacement of the LIP halved the area of the Amerasia Basin, and the area lying south of the LIP became the Canada Basin.

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“…Water depths exceeding 3,500 m, dispersion patterns of Lg-phase seismic waves (Oliver and others, 1955), and seismic refraction measurements (Mair and Lyons, 1981;Grantz and others, 1981) indicate that the Canada basin is underlain by oceanic crust and was therefore formed by seafloor spreading. The inferred thickness of sediment in the southern part of the basin is shown in Figure 6 and the three major physiographic provinces into which it can be subdivided are shown in Figure 16.…”

Section: Canada Basinmentioning

confidence: 99%

Geologic framework, hydrocarbon potential, and environmental conditions for exploration and development of proposed oil and gas lease sale 87 in the Beaufort and northeast Chukchi Seas: A summary report

Grantz¹,

Dinter²,

Hill³

et al. 1982

Open-File Report

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Crustal structure and velocity anisotropy beneath the Beaufort Sea

Cited by 41 publications

References 0 publications

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Chapter 50 Geology and tectonic development of the Amerasia and Canada Basins, Arctic Ocean

Geologic framework, hydrocarbon potential, and environmental conditions for exploration and development of proposed oil and gas lease sale 87 in the Beaufort and northeast Chukchi Seas: A summary report

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