New seismic, magnetic, and gravity constraints on the crustal structure of the Lincoln Sea continent–ocean transition

Forsyth, David; Argyle, Malcolm; Okulitch, A V; Trettin, H P

doi:10.1139/e94-082

Cited by 17 publications

(20 citation statements)

References 28 publications

(29 reference statements)

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“…The crustal thicknesses include a sedimentary sequence, associated with the basin, of up to 15 km in thickness. Studies carried out to the north of the Arctic islands, across the continental margin, indicate crustal thicknesses of ∼22–30 km on the continental shelf edge (Berry & Barr 1971; Asudeh et al 1989; Forsyth et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Darbyshire¹

2003

Geophysical Journal International

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SUMMARY Results from an investigation of the crustal structure beneath the Canadian High Arctic and western Greenland are presented, using teleseismic data recorded by a network of 12 three‐component broad‐band seismograph stations deployed across the region. Of these stations, eight were deployed in summer 2000, in order to improve the spatial density of seismographs in this tectonically active but little studied region, in order to provide more information on the patterns of seismicity and the structure of the area. The typical station separation is of the order of 400–600 km, a substantial improvement on the previous >1000 km spacing afforded by the permanent broad‐band network. Teleseismic receiver functions are used to model the shear wave velocity structure of the crust beneath the stations, using both 1‐D and 3‐D analysis techniques. The velocity–depth models show significant variation in the thickness and nature of the crust across the region. In the south and east, where the seismic stations lie on the Canadian Shield, the crustal structure is relatively simple, with Moho depths ranging from 35 km on the Boothia Peninsula to 45 km beneath southern Baffin Island. Further to the north and west, where the lithosphere has been deformed by orogenic events and basin formation, the patterns of azimuthal variation in the radial and tangential receiver functions suggest 3‐D structure throughout the crust. The Moho depths around the margins of the Sverdrup Basin lie in the range 33–37 km. At Mould Bay, on the western margin of the basin, a 5 km thick low‐velocity layer overlies the main crustal sequence. The base of this layer can be modelled as a planar dipping structure with a southeasterly strike. The thinnest crust (27–32 km) is modelled at Alert, on the northern coast of Ellesmere Island. In the southwest of the Arctic archipelago, tangential receiver functions at Holman show a pattern consistent with crustal anisotropy. The Moho depth in the region is undetermined; a layer of intermediate shear wave velocity, consistent with mafic lower‐crustal material, is modelled at depths of 35–55 km. The region around Holman lies at the focal point of the Mackenzie dyke swarm, believed to result from plume activity; therefore the intermediate‐velocity layer may result from mafic underplating caused by the presence of the Mackenzie plume.

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Section: Introductionmentioning

confidence: 99%

Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Darbyshire¹

2003

Geophysical Journal International

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“…North of the Canadian Arctic margin, at approximately 828N 608W, the Lomonosov microcontinent widens and swings westward from an otherwise linear trend, producing the Lincoln Sea plateau of Forsyth et al (1994). The location of the boundary between the microcontinent and the Alpha -Mendeleev magmatic rocks is not sharply defined by potential field data in this area, but its position is limited on the east by seismic data (Kristoffersen & Mikkelsen 2006).…”

Section: Boundaries With the Eurasia And Amerasia Basinsmentioning

confidence: 88%

“…The apparent gradual transition of the potential field data across the boundary suggests that the Alpha -Mendeleev mafic rocks are banked against, and lap onto, the microcontinent. Gravity and magnetic modelling suggest that the microcontinent is intruded and/or underplated by mafic rocks in this area (Kovacs & Vogt 1982;Forsyth et al 1994), indicating that the postulated hot spot track that formed the Alpha -Mendeleev Ridge may have crossed this part of the microcontinent.…”

Section: Boundaries With the Eurasia And Amerasia Basinsmentioning

confidence: 94%

“…This view is supported by bathymetry in the Lincoln Sea, which shows that a .1 km-deep, linear trough lies between the Greenland -Canadian margin and the Lomonosov microcontinent. The seismic refraction model of Forsyth et al (1994) across the Canadian margin and the southern margin of the trough suggests a crustal transition that passes from an extended continental margin on the south to near oceanic crust in the axial part of the trough. The presence of a continent-ocean transition between the Canadian margin and the Lomonosov microcontinent suggests that a triangular sliver of ocean crust could be trapped in the trough between the microcontinent and the Canadian -Greenland margin (Figs 49.4 & 49.5).…”

Section: Boundaries With the Siberian And Greenland -Canadian Marginsmentioning

confidence: 99%

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Chapter 49 A first look at the petroleum geology of the Lomonosov Ridge microcontinent, Arctic Ocean

Moore

Grantz²,

Pitman

et al. 2011

Memoirs

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The Lomonosov microcontinent is an elongated continental fragment that transects the Arctic Ocean between North America and Siberia via the North Pole. Although it lies beneath polar pack ice, the geological framework of the microcontinent is inferred from sparse seismic reflection data, a few cores, potential field data and the geology of its conjugate margin in the Barents–Kara Shelf. Petroleum systems inferred to be potentially active are comparable to those sourced by condensed Triassic and Jurassic marine shale of the Barents Platform and by condensed Jurassic and (or) Cretaceous shale probably present in the adjacent Amerasia Basin. Cenozoic deposits are known to contain rich petroleum source rocks but are too thermally immature to have generated petroleum. For the 2008 USGS Circum Arctic Resource Appraisal (CARA), the microcontinent was divided into shelf and slope assessment units (AUs) at the tectonic hinge line along the Amerasia Basin margin. A low to moderate probability of accumulation in the slope AU yielded fully risked mean estimates of 123 MMBO oil and 740 BCF gas. For the shelf AU, no quantitative assessment was made because the probability of petroleum accumulations of the 50 MMBOE minimum size was estimated to be less than 10% owing to rift-related uplift, erosion and faulting.

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“…NRL has now completed seven field seasons in the Arctic, measuring gravity and magnetics along 210,000 line km, covering nearly two thirds of the Arctic Ocean basins (Figure 2). In addition, a host of smaller-scale, higherresolution airborne surveys have been conducted in the Arctic, using smaller twin engine aircraft, by Danish, Norwegian, German, and Canadian researchers Forsyth et al, 1994;Timmen et al, 1998]. …”

Section: Nrl Aerogravimetrymentioning

confidence: 99%

New gravity data in the Arctic Ocean: Comparison of airborne and ERS gravity

Childers¹,

McAdoo²,

Brozena³

et al. 2001

J. Geophys. Res.

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Abstract. New gravity fields from airborne gravimetry and from ERS-1 and -2 satellite altimetry cover extensive portions of the Arctic Ocean. These two data sets may constitute as much as 60% of the data contributions to the Arctic Gravity Project compilation. Here we evaluate the accuracy and resolution of these data and quantify their impact on the compilation. Both gravity determinations compare favorably with Geological Survey of Canada surface measurements in the Beaufort Sea (airborne, 1.86-2.09 mGal rms; ERS, 2.64-3.11 mGal rms). Comparisons between the airborne and ERS data over the Chukchi Borderlands reveal a 4.38 mGal rms difference over the smoother region of the field and 7.36 mGal rms over the rugose field generated by the shallow ridges and deep troughs. Coherency between the two data sets in the Chukchi region implies a resolution of 19 km. Comparison with Science Ice Expedition submarine measurements over Chukchi Plateau suggests that the ERS field resolves even shorter-wavelength signal than the airborne data, whereas in the Beaufort Sea the airborne data showed better coherence to ground truth data. Long-wavelength differences exist between the two data sets, expressed as a 2-3 mGal offset over the Chukchi region. This study highlights the respective strengths of the two data sets. The ERS gravity field has the advantage of ubiquitous coverage of the ocean south of 81.5øN, a denser sampling of the gravity field, and a recovery of signal down to -15 km. The airborne data cover a significant portion of the polar hole in the satellite coverage, have lower measurement noise, and recover somewhat higher anomaly amplitudes in the 25-100 km wavelength range. IntroductionThe origin and evolution of the Arctic Ocean are two of the largest remaining uncertainties in plate tectonics. Whereas the opening histories of the world's other major ocean basins have been understood for more than 20 years, the formation of the Arctic's Amerasia Basin remains a mysteu. To date, the primary impediment to a fuller tectonic understanding has been the dearth of available geophysical data in the Arctic Ocean. Logistical problems, due to the year-round ice cover, were compounded by Cold War political sensitivities; as a result, the ocean basin was poorly sampled with bathymetry, gravity, and magnetics data. Moreover, much of the data actually collected , of which these two data sets will constitute a significant contribution, it is important to understand how these data sets compare in terms of accuracy and resolution. This study compares these two data sets over two regions of overlap in the Amerasia Basin. First, both sets are compared separately with high-quality ice surface gravity measurements in the Beaufort Sea region (Figure 1) of the Canada Basin, and then with each other and with Science Ice Expedition (SCICEX) submarine gravity measurements over the rugose gravity field of the Chukchi Borderland.

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New seismic, magnetic, and gravity constraints on the crustal structure of the Lincoln Sea continent–ocean transition

Cited by 17 publications

References 28 publications

Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Chapter 49 A first look at the petroleum geology of the Lomonosov Ridge microcontinent, Arctic Ocean

New gravity data in the Arctic Ocean: Comparison of airborne and ERS gravity

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