Crust and uppermost-mantle structure of Greenland and the Northwest Atlantic from Rayleigh wave group velocity tomography

Darbyshire, F. A.; Dahl‐Jensen, Trine; Larsen, Tine B.; Voß, Peter; Joyal, Guillaume

doi:10.1093/gji/ggx479

Cited by 34 publications

(83 citation statements)

References 83 publications

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“…From this region, relatively thick crust extends southward and eastward and coincides with part of the South Archean Block, Eastern Archean Block, and Nagssugtoqidian orogen. In northern Greenland, our model does not indicate crustal thinning as suggested by gravity‐based models (Braun et al, ; Petrov et al, ; Schiffer et al, ; Steffen et al, ) but is relatively consistent with surface wave‐based crustal thickness models (Darbyshire et al, ; Mordret, ). The high degree of heterogeneity in crustal thickness estimates in northern Greenland may be the result of the limited sensitivity of surface waves.…”

Section: Resultssupporting

confidence: 73%

“…Constraints on crustal velocity structure are limited, and general agreement on crustal structure remains a goal. Regional crustal shear wave tomography models from earthquake or ambient noise data suggest the presence of a low‐velocity anomaly in northeastern and central eastern Greenland, but the amplitude and location of this anomaly differ between studies (Darbyshire et al, ; Levshin et al, ; Mordret, ).…”

Section: Introductionmentioning

confidence: 98%

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Lithospheric Structure of Greenland From Ambient Noise and Earthquake Surface Wave Tomography

Pourpoint¹,

Anandakrishnan

Ammon

et al. 2018

JGR Solid Earth

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We present a high‐resolution shear wave velocity model of Greenland's lithosphere from regional and teleseismic Rayleigh waves recorded by the Greenland Ice Sheet Monitoring Network supplemented with observations from several temporary seismic deployments. To construct Rayleigh wave group velocity maps, we integrated signals from regional and teleseismic earthquakes with several years of ambient seismic noise and used the dispersion to constrain crustal and upper‐mantle seismic shear wave velocity structure. Specifically, we used a Markov Chain Monte Carlo technique to estimate 3‐D shear wave velocities beneath Greenland to a depth of 200 km. Our model reveals four prominent anomalies: a deep high‐velocity feature extending from southwestern to northwestern Greenland that may be the signature of a thick cratonic keel, a corridor of relatively low upper‐mantle velocity across central Greenland that could be associated with lithospheric modification from the passage of the Iceland plume beneath Greenland or interpreted as a tectonic boundary between cratonic blocks, an upper‐crustal southwest‐northeast trending boundary separating Greenland into two regions of contrasting tectonic and crustal properties, and a midcrustal low‐velocity anomaly beneath northeastern Greenland. The nature of this midcrustal anomaly is of particular interest given that it underlies the onset of the Northeast Greenland Ice Stream and raises interesting questions regarding how deeper processes may impact the ice stream dynamics and the evolution of the Greenland Ice Sheet.

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Section: Resultssupporting

confidence: 73%

Section: Introductionmentioning

confidence: 98%

Lithospheric Structure of Greenland From Ambient Noise and Earthquake Surface Wave Tomography

Pourpoint¹,

Anandakrishnan

Ammon

et al. 2018

JGR Solid Earth

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“…While the model by Priestley and McKenzie (2013) shows a thinner LAB toward the south to values of 100 km, the model by Schaeffer and Lebedev (2013) has a deep LAB at 220 km in the southern part and a LAB of 180 km in central Greenland. A recent local model by Darbyshire et al (2018) shows fast shear wave velocities beneath entire Greenland at depths between 55 and 90 km. Even the T e anomaly between North America and Greenland is visible as a small anomaly in the LAB distribution.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, other geophysical methods such as receiver functions, tomography, and gravity modeling can be used to obtain information on the lithospheric structure (e.g., Artemieva & Thybo, 2013;Braun et al, 2007;Dahl-Jensen et al, 2003;Darbyshire et al, 2018;Steffen et al, 2017). The thick ice cover also impedes the gathering of active source seismic data (reflection and refraction), thus hampering geophysical mapping of tectonic structures that are useful for accurate tectonic reconstructions and the estimation of current thermorheological properties.…”

Section: Introductionmentioning

confidence: 99%

Weakened Lithosphere Beneath Greenland Inferred From Effective Elastic Thickness: A Hot Spot Effect?

Steffen

Audet

Lund

2018

Geophysical Research Letters

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The effective elastic thickness (Te) of the lithosphere provides geophysical information about long‐term flexural strength and can be used to constrain thermorheological properties of the lithosphere. Te is typically calculated from the spectral analysis of gravity and topography data; variations in Te are, however, not well resolved in Greenland due to poor constraints on crustal structure (including crustal thickness) and complications due to ice loading. In addition, geological and geophysical constraints on the tectonic history of Greenland are sparse due to the thick ice cover. Here we use the global gravity model EIGEN‐6C4 together with a new model of the crust‐mantle boundary to obtain a high‐resolution Te map of Greenland. The distribution of Te indicates reduced strength in the lower crust and lithospheric mantle beneath southern and central Greenland, which may be due to the passage of the Iceland hot spot during the last 100 Ma. In contrast, the northern part of Greenland shows a large Te, implying mechanical coupling between crust and uppermost mantle and suggesting the existence of a cold and strong tectonic unit. In a relative sense, the distribution of Te values is consistent with estimates of lithospheric thickness based on seismic velocity models, indicating a dominantly thermal control on lithospheric structure and evolution.

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“…Crustal thickness and depth to Moho have been computed for Greenland and adjacent regions by using (1) gravity data (Steffen et al, ) and (2) seismological data (Darbyshire et al, ; Mordret, and Pourpoint et al, ). Our depth to Moho (Figure a) is comparable with the model of Darbyshire et al () who used Rayleigh wave anisotropic group velocity tomography to map the 3‐D crustal structure of Greenland and NW Atlantic Ocean. Both models show a 40‐ to 55‐km depth to Moho for most of the Greenland continent, with thinner crust in eastern Greenland.…”

Section: Resultsmentioning

confidence: 99%

ArcCRUST: Arctic Crustal Thickness From 3‐D Gravity Inversion

Lebedeva‐Ivanova

Gaina

Minakov

et al. 2019

Geochem Geophys Geosyst

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The ArcCRUST model consists of crustal thickness and estimated crustal thinning factors grids for the High Arctic and Circum‐Arctic regions (north of 67°N). This model is derived by using 3‐D forward and inverse gravity modeling. Updated sedimentary thickness grid, an oceanic lithosphere age model together with inferred microcontinent rifting ages, variable crystalline crust and sediment densities, and dynamic topography models constrain this inversion. We use published high‐quality 2‐D seismic crustal‐scale models to create a database of Depths to Seismic Moho (DSM) profiles. To check the quality of the ArcCRUST model, we have performed a statistical analysis of misfits between the ArcCRUST Moho depths and DSM values. Systematic analysis of the misfits within the Arctic sedimentary basins provides information about tectonic processes unaccounted by the assumed model of pure‐shear lithospheric extension. In particular, our model implies a less dense and/or thin mantle lithosphere underneath microcontinents in the deep Arctic Ocean where the ArcCRUST depth to Moho values exceed the DSM. A systematically larger gravity‐derived crustal thickness (~3 km) under the western and northern Greenland Sea points to a hotter upper mantle implied by the seismic tomography models in the North Atlantic.

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Crust and uppermost-mantle structure of Greenland and the Northwest Atlantic from Rayleigh wave group velocity tomography

Cited by 34 publications

References 83 publications

Lithospheric Structure of Greenland From Ambient Noise and Earthquake Surface Wave Tomography

Lithospheric Structure of Greenland From Ambient Noise and Earthquake Surface Wave Tomography

Weakened Lithosphere Beneath Greenland Inferred From Effective Elastic Thickness: A Hot Spot Effect?

ArcCRUST: Arctic Crustal Thickness From 3‐D Gravity Inversion

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