Crustal structure across the Bering Strait, Alaska: Onshore recordings of a marine seismic survey

Wolf, Lorraine W.; McCaleb, Robert C.; Stone, David B.; Brocher, Thomas M.; Fujita, Kazuya; Klemperer, S. L.

doi:10.1130/0-8137-2360-4.25

Cited by 5 publications

(5 citation statements)

References 26 publications

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“…(1998) suggest the Chukchi Plateau is a region of thinned continental crust. Hunkins (1966) and Wolf et al . (2002), estimate crustal thickness of the outer Chukchi Shelf at ∼32 km depth.…”

Section: Experiments Overview Methodology and Resultsmentioning

confidence: 92%

“…Previous studies by Hunkins (1966), Hall (1970), Weber & Sweeney (1990) and Grantz et al (1998) suggest the Chukchi Plateau is a region of thinned continental crust. Hunkins (1966) and Wolf et al (2002), estimate crustal thickness of the outer Chukchi Shelf at ∼32 km depth. The Chukchi Plateau however is likely more extended than the shelf.…”

Section: Resultsmentioning

confidence: 99%

“…The Chukchi Borderland has long been considered a thinned continental fragment (Fig. 1; Hunkins 1966; Hall 1990; Laxon & McAdoo 1994; Klemperer et al 2002; Wolf et al 2002). Consistent with the rotational model for the Canada Basin, Grantz et al .…”

Section: Geological Settingmentioning

confidence: 99%

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Bathymetry, controlled source seismic and gravity observations of the Mendeleev ridge; implications for ridge structure, origin, and regional tectonics

Dove

Coakley

Hopper

et al. 2010

Geophysical Journal International

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S U M M A R YMultichannel seismic (MCS), seismic refraction, and gravity data collected down the flank of the Chukchi Plateau, but predominantly over the Mendeleev Ridge have been processed and interpreted to describe the crustal style of the ridge, as well as the structural history. These results provide constraints on the origin of the ridge, and the tectonic evolution of the Amerasian Basin. MCS images reveal two primary sediment sequences separated by an unconformity that persists across the entire Mendeleev Ridge. The basement and lower sediment sequence exhibit pervasive normal faulting. The upper sequence is laterally conformable and not effected by faulting, thus the regional unconformity dividing the two sequences is interpreted to mark the end of extensional deformation. Modeling of sonobuoy seismic refraction data reveals upper crustal P-wave velocities ranging from 3.5 to 6.4 km s −1 approximately 5 km into the basement. The velocity structure of the Mendeleev Ridge is consistent with either a volcanic rifted continental margin, or an oceanic plateau origin. Observed gravity anomalies over the ridge are reproduced by a model consisting of bathymetry, sediment and basement horizons from the MCS data and a single crustal layer of 2.86 g cm −3 . This result is consistent with homogeneous, mafic crust. The similar velocity and density structures of the Mendeleev and Alpha ridges is consistent with a model where the two ridges are contiguous and share a common geological origin. Gravity modelling over the transition between the Chukchi Plateau and the Mendeleev Ridge suggests the two features have differing compositions and distinct emplacement histories. Three tectonic models are presented for the origin of the Alpha Mendeleev Ridge (AMR) that satisfy constraints set by this and previous studies: (1) a rifted volcanic continental margin, (2) an oceanic plateau formed at a spreading centreperpendicular to the AMR and (3) an oceanic plateau formed at a spreading centre-parallel to the AMR.

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Section: Experiments Overview Methodology and Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

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Bathymetry, controlled source seismic and gravity observations of the Mendeleev ridge; implications for ridge structure, origin, and regional tectonics

Dove

Coakley

Hopper

et al. 2010

Geophysical Journal International

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“…Deep seismic refl ection profi ling through the Bering Strait region shows that the Moho at the latitude of Seward Peninsula has little topography Wolf et al, 2002). Like the crust beneath the Basin and Range province, the crust under Seward Peninsula and the Bering Strait is characterized by subhorizontal refl ectivity thought to indicate fl ow and mobility of the lower crust.…”

Section: Conclusion and Regional Implicationsmentioning

confidence: 98%

Geologic map and summary of the evolution of the Kigluaik Mountains gneiss dome, Seward Peninsula, Alaska

Amato¹,

Miller²

2004

Gneiss Domes in Orogeny

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Geologic mapping of the Kigluaik gneiss dome on Seward Peninsula, Alaska, was conducted at 1:24,000 scale and compiled with thesis maps and published maps as a colored map covering eight 15″ quadrangles at 1:63,360 scale. The Kigluaik dome consists of an exceptionally well-exposed 15-km-thick structural section of metasedimentary rocks and orthogneisses. A 91 ± 1 Ma upper-amphibolite-to-granulite facies metamorphic event that was syntectonic with gneiss dome fabrics overprints a pre-120 Ma blueschist-to-greenschist facies event. Peak conditions associated with younger metamorphism increase from greenschist facies in the structurally higher rocks of the Nome Group, through biotite, staurolite, sillimanite, and second sillimanite isograds to granulite facies in the rocks of the Kigluaik Group. The high-grade overprint is coeval with mantle-derived magmatism at 90 ± 1 Ma. Mafi c magmatism provided heat for metamorphism and induced partial melting, also enabling fl ow of gneisses. Deformation thinned the crust as the gneiss dome was exhumed, collapsing isograds and juxtaposing rocks that equilibrated at dramatically different structural levels. Lineations in the gneiss dome record a rotation of stretching directions with structural depth. The continuous transition of lineation azimuth and the lack of overprinting relationships indicate orthogonal stretching directions at different structural levels in the gneiss dome during its formation. Based on regional geologic relations, it is likely that the Bering Strait gneiss domes developed within a continental arc that was undergoing extension, probably as the result of rollback of the north-dipping subducting slab along the Pacifi c margin during Late Cretaceous time.

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“…However, gravity data show only a minor gravity low where the Herald Arch and Hope Basin are located and modeling indicates a lack of a crustal root (Wolf et al, 2002). The tectonic process required to produce the observed crustal thinning has not been explained by the inferred geologic history of the Hope Basin, Herald Arch and Brooks Range orogeny.…”

Section: Chapter 1: Introductionmentioning

confidence: 87%

Structure and crustal balance of the Herald Arch and Hope Basin in the Chukchi Sea, Alaska

Patthoff¹

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Sea, off the northwest coast of Alaska. The thrust continues for approximately 60 kilometers from the northwest tip of the Lisburne Peninsula into the Chukchi Sea. Its dip varies from nearly 60 degrees in the east, to 20 degrees in the west before terminating on the available seismic data. Closer to the shore, the detachment of the Herald Thrust occurs at the edge of a Devonian rift basin containing the Franklinian Sequence. Moving towards the northwest, the rift diminishes along with the detachment of the Herald Thrust. Northeast of the Herald Thrust in the Colville Basin, the anticlines and thrust faults of the Brookian layers diminish in magnitude and displacement from the Lisburne Peninsula to the northwest. The depth to the reflection Moho decreases from approximately 37 km beneath the Colville Basin to 28 km under the Hope Basin to the south. Estimates for the amount of extension required to produce the present day crustal thickness are at least 20% less than the amount of Tertiary stretching that has been documented by restoration of supracrustal normal faults. The thinning of the crust could be attributed to differential spreading where the upper crust was stretched less then the lower crust and mantle, or due to and older, mid Cretaceous, extensional event that has gone unrecognized on the seismic data. A magnetic high that corresponds closely to the Herald Arch could be evidence of magmatic material brought up during the mid-Cretaceous spreading event.

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Crustal structure across the Bering Strait, Alaska: Onshore recordings of a marine seismic survey

Cited by 5 publications

References 26 publications

Bathymetry, controlled source seismic and gravity observations of the Mendeleev ridge; implications for ridge structure, origin, and regional tectonics

Bathymetry, controlled source seismic and gravity observations of the Mendeleev ridge; implications for ridge structure, origin, and regional tectonics

Geologic map and summary of the evolution of the Kigluaik Mountains gneiss dome, Seward Peninsula, Alaska

Structure and crustal balance of the Herald Arch and Hope Basin in the Chukchi Sea, Alaska

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