A new approach to assess isostatic compensation of topography in continental domain from GOCE gravity gradients

Cadio, C.; Saraswati, Anita Thea; Cattin, Rodolphe; Mazzotti, S.

doi:10.1093/gji/ggw281

Cited by 6 publications

(3 citation statements)

References 35 publications

(46 reference statements)

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“…Seismic velocity models of the crust developed in the last decade (i.e., since deployment of the US-Array TA EarthScope network) confirm that the Moho is broadly flat and shallow across the NCC, with only slight (∼2 km) thickening inferred beneath the MM constrained by sparse data, indicating that there is no Airy-type or otherwise extensive Cordilleran crustal root. This is in contradiction with a satellite gravity gradiometric study (Cadio et al, 2016), which suggests that the topography is perfectly compensated across the NCC interior. In addition, these velocity models suggest that crustal temperatures throughout the NCC are exceptionally high with a Moho temperature reaching 800-900°C (Hyndman, 2017;Audet et al, 2019).…”

Section: Current Tectonicscontrasting

confidence: 96%

Structure, origin, and deformation of the lithosphere in the northern Canadian Cordillera from high-resolution, passive-source seismic velocity models

Estève¹,

Audet

Schutt

et al. 2023

Preprint

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The recent deployment of temporary broadband seismic networks, notably the EarthScope USArray-Transportable Array (TA), has drastically improved the station coverage across northwestern Canada over the last ten years, enabling application of high-resolution passive-source seismic methods (i.e., seismic tomography, receiver functions and core phase shear wave splitting). This review highlights the main discoveries pertaining to the seismic velocity structure, origin and deformation of the lithosphere in the northern Canadian Cordillera (NCC). High-resolution seismic tomography models reveal that the lower crust in the NCC is marked by low velocity anomalies extending from the Gulf of Alaska to the Cordilleran deformation front, which are interpreted to reflect elevated temperatures that buoyantly support regional high elevations and potentially represent the seismic signature of strain transfer from the Yakutat collision zone to the Mackenzie Mountains. The Moho is relatively flat and shallow across the NCC, and is underlain by a thin layer of mantle lithosphere. Seismic velocity models further unveiled large-scale mantle structures associated with the unexposed Mackenzie craton in the north, and the Liard Transfer Zone in the south, which appear to buttress the NCC and further focus deformation in the eastern NCC. Seismic anisotropy and tomography provide evidence that the Tintina and Denali faults penetrate into the lithospheric mantle and played a first order role in shaping the present-day NCC. We propose that future studies should aim to: 1) resolve the shape of the Cordillera-craton boundary at upper mantle depths; 2) accurately estimate the lithosphere thickness in the NCC; and 3) improve coverage in the Beaufort Sea to understand the controls on convergent tectonics in the northern NCC.

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Section: Current Tectonicscontrasting

confidence: 96%

Structure, origin, and deformation of the lithosphere in the northern Canadian Cordillera from high-resolution, passive-source seismic velocity models

Estève¹,

Audet

Schutt

et al. 2023

Preprint

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“…We therefore propose in this study, in addition to the Moho undulations from the gravimetric inversion, a Moho calculated from the isostatic-gravimetric methods. Then, the comparison of these 2 quantities will allow to have an overview of different factors responsible for the surface deformations and to draw some conclusions on the geodynamics of the region [36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Crustal Thickness Variations and Tectonic Settings in the Southwest Cameroon Inferred from Gravity and Topography Data

et al. 2022

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EIGEN 6C4 gravity anomalies are interpreted to determine the lateral and vertical variations in the crust and upper mantle structure and their influence on the isostasy of the coastal plain, transition zone between the Congo Craton (CC), the Pan-African Belt (PAB), and adjacent areas. The regional gravity anomalies have been inverted in an attempt to provide a Moho depth map. The inversion process was based on the Parker-Oldenburg method with a density contrast of 0.55 g/cm3 and an average depth reference of 39 km. In addition, various tests have been performed to validate the resulting Moho model and estimate the efficiency of the 3D gravity inversion by varying the density contrast for a fixed Moho reference depth. Inversion results reveal that the Moho depths generally agree with those obtained from previous geophysical studies. The computation of the isostatic models using the ETOPO1 digital elevation model (DEM) and its comparison with the Moho models obtained from gravity induce the following main conclusions: (1) an overcompensated crust beneath the coastal plain and the Yaounde Domain, (2) the crust beneath areas located in the southern end of the Adamawa-Yade Domain is thin and undercompensated, and (3) main volcanoes of the Southwestern Cameroon Volcanic Line (CVL) are isostatically undercompensated. This study also revealed that the local isostatic compensation law is not satisfied for most of the tectonic provinces of the study area, and we suggest alternative tectonic mechanisms to support topography below these tectonic features. Additionally, most seismic events (M>3.5) occurred in areas marked by abrupt changes in compensation amplitude. Thus, we concluded from this study that the northern limit of the CC, the Mount Cameroon, and its surroundings are tectonic extension areas that may play a crucial role in the occurrence of future earthquakes.

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“…This geometric description of the field variations can be efficiently realized through the gravity gradients tensor, an observable on the rates of variation of the gravity vector in the three directions of space. Recently mapped at planetary scales from the Gravity field and steady‐state Ocean Circulation Explorer mission, satellite gravity gradients have thus been used to investigate the Earth's crust and mantle structure (see, for instance, Bouman et al, ; Fullea et al, ; McKenzie et al, , and references herein; Cadio et al, ; Greff‐Lefftz et al, ). They help identify a source from the shape of its gravity signal, even down to lower mantle depths (Panet et al, ).…”

Section: Introductionmentioning

confidence: 99%

An Analysis of Gravitational Gradients in Rotated Frames and Their Relation to Oriented Mass Sources

Panet

2018

JGR Solid Earth

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Many mass sources within the Earth and its fluid envelopes show elongated geometries, aligning with the orientations of plate boundaries and plate motions, coastlines, rivers, and drainage basins for instance. To enhance their identification and separation in global or regional gravity observations and models, a dedicated method based on gravitational gradients analysis is presented here. This approach provides a detailed description of the geographic pattern of the gravity variations, which are accurately mapped thanks to the regular spatial coverage of high‐accuracy satellite data and arise from lateral density changes within the planet. First, gravity gradients are defined at different spatial scales in spherical frames, which are rotated along the radial axis according to the orientation of the source. The sensitivity of these gradients to the mass distribution inside a spherical Earth is described and analytical expressions relating the source to the observable are introduced. Then, the gravity gradients responses at different spatial scales to flat, elementary mass sources located at the surface and at increasing depth are studied. Specifically, the paper investigates how a source width and orientation can be determined, for localized and oscillatory mass anomalies with different width‐to‐length aspect ratios. This theoretical case study aims at providing a basis for the analysis of more complex mass structures, when applying the presented method to static or time‐varying satellite gravity field models. It may help deciphering the nature of the gravity sources by the detection of meaningful geometries and orientations in the gravity field.

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A new approach to assess isostatic compensation of topography in continental domain from GOCE gravity gradients

Cited by 6 publications

References 35 publications

Structure, origin, and deformation of the lithosphere in the northern Canadian Cordillera from high-resolution, passive-source seismic velocity models

Structure, origin, and deformation of the lithosphere in the northern Canadian Cordillera from high-resolution, passive-source seismic velocity models

Crustal Thickness Variations and Tectonic Settings in the Southwest Cameroon Inferred from Gravity and Topography Data

An Analysis of Gravitational Gradients in Rotated Frames and Their Relation to Oriented Mass Sources

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