Reply [to “Comments on ‘Comparison of long-wavelength residual elevation and free air gravity anomalies in the North Atlantic and possible implications for the thickness of the lithospheric plate’ by John G. Sclater, Lawrence A. Lawver, and Barry Parsons”

1976 ◽  
Vol 81 (26) ◽  
pp. 4960-4964 ◽  
Author(s):  
John G. Sclater ◽  
Barry Parsons
Keyword(s):  
North Atlantic ◽  
Gravity Anomalies ◽  
Lithospheric Plate ◽  
Long Wavelength ◽  
The North ◽  
Free Air ◽  
The North Atlantic ◽  
Free Air Gravity

Empirical Determination of the Gravity Anomaly Covariance Function in Mountainous Areas

1980 ◽  
Vol 34 (3) ◽  
pp. 251-264 ◽  
Author(s):  
Gerard Lachapelle ◽  
K. P. Schwarz
Keyword(s):  
Gravity Anomaly ◽  
Covariance Function ◽  
Physical Geodesy ◽  
Gravity Anomalies ◽  
Mountainous Areas ◽  
The North ◽  
Regression Parameters ◽  
Free Air ◽  
Vening Meinesz ◽  
Free Air Gravity

An evaluation of the empirical gravity anomaly covariance function using over 95 000 surface gravity anomalies in the North American Western Cordillera was carried out. A regression analysis of the data exhibits a strong and quasi-linear correlation of free air gravity anomalies with heights. This height correlation is removed from the free air anomalies prior to the numerical evaluation of the gravity anomaly covariance function. This covariance function agrees well with that evaluated previously by the authors for the remainder of Canada. A possible use for such a covariance function of ‘height independent’ gravity anomalies in mountainous areas is described. First, the height independent gravity anomaly at a point of known height is evaluated by least squares prediction using neighboring measured height independent gravity anomalies. Secondly, the part caused by the height correlation is calculated using linear regression parameters estimated previously and added to the predicted height independent gravity anomaly to obtain a predicted standard free air anomaly. This technique can be used to densify the coverage of free air anomalies for subsequent use in integral formulas of physical geodesy, e.g., those of Stokes and Vening Meinesz. This method requires that point topographic heights be given on a grid.

scholarly journals Response of a low subsiding intracratonic basin to long wavelength deformations: the Palaeocene–early Eocene period in the Paris basin

2015 ◽  
Vol 7 (4) ◽  
pp. 3587-3643
Author(s):  
J. Briais ◽  
F. Guillocheau ◽  
E. Lasseur ◽  
C. Robin ◽  
J. J. Châteauneuf ◽  
...  
Keyword(s):  
North Atlantic ◽  
Geodynamic Setting ◽  
Paris Basin ◽  
Eurasian Plate ◽  
Massif Central ◽  
Sequence Stratigraphic ◽  
Long Wavelength ◽  
The North ◽  
Pattern Sequence ◽  
The North Atlantic

Abstract. The uppermost Cretaceous to early Palaeogene is a period of major deformations of the western part of the Eurasian plate with prominent basin inversions starting from the Coniacian onwards. These deformations occur in a complex geodynamic setting within both the context of the Africa–Eurasia convergence and the North Atlantic opening. While Mesozoic graben inversions have been extensively studied, particularly in Eastern Europe and the North Sea, more gentle deformations that affect thicker crust areas (intracratonic basins and emerged lands) are not as well documented. The objective of this study is to constrain the exact timing, type and magnitude of the early Palaeogene deformations affecting the intracratonic Paris basin and to integrate them at the Western European scale. Relatively gentle deformations are attempted through a high-resolution reconstitution of its stratigraphic record based on outcrops and well-dated wells, and a high number of well-logs that are correlated using the "stacking pattern" sequence stratigraphic technique. Two orders of sequences are identified (third- and fourth-order) and correlated throughout the basin. Basin geometric and palaeogeographic reconstitutions are based on sediment thickness and facies analysis. Two-dimensional accommodation space measurements were taken in order to quantify the magnitude of the deformations. Three phases of deformation were recognized. 1. An intra-Maastrichtian–pre-Thanetian (59 Ma) deformation, with major uplift and erosion of the Cretaceous strata with two sub-periods of deformation: Maastrichtian–pre-middle-Danian and Upper Danian–pre-Thanetian long wavelength deformations. This period of major deformation is coeval with Upper Cretaceous–pre-Danian compressive deformations linked to the Africa–Eurasia convergence in southern France and with volcanic activity from the North Atlantic to Massif Central and the Rhenish Shield during the Palaeocene; 2. an early Ypresian (55.1–54.3 Ma) medium wavelength deformation (× 10 km), here reported to be a stress rearrangement related to the onset of the North Atlantic opening; 3. an uppermost Ypresian (49.8 Ma) long wavelength deformation (× 100 km), contemporaneous with flexural compressive deformations in the Aquitaine Basin (Pyrenean deformation), and related to the Iberia–Eurasia convergence.

scholarly journals Gravity anomalies, regional elevation, and the deep structure of the North Atlantic

1978 ◽  
Vol 83 (B10) ◽  
pp. 4907-4924 ◽  
Author(s):  
James R. Cochran ◽  
Manik Talwani
Keyword(s):  
North Atlantic ◽  
Deep Structure ◽  
Gravity Anomalies ◽  
The North ◽  
The North Atlantic

Crustal modeling of the North Atlantic from spectrally correlated free-air and terrain gravity

2005 ◽  
Vol 40 (1) ◽  
pp. 23-50 ◽  
Author(s):  
Timothy E. Leftwich ◽  
Ralph R.B. von Frese ◽  
Laramie V. Potts ◽  
Hyung Rae Kim ◽  
Daniel R. Roman ◽  
...  
Keyword(s):  
North Atlantic ◽  
The North ◽  
Free Air ◽  
The North Atlantic

Anomalous Topography, Bathymetry, Crust and Mantle in the North Atlantic Region

2020 ◽  
Author(s):  
Hans Thybo ◽  
Irina Artemieva
Keyword(s):  
Heat Flow ◽  
North Atlantic ◽  
Gravity Anomalies ◽  
Square Root ◽  
Age Dependence ◽  
North Atlantic Region ◽  
Atlantic Region ◽  
Spreading Ridges ◽  
Free Air ◽  
Free Air Gravity

<p>The whole North Atlantic region has highly anomalous topography and bathymetry. Observations show evidence for substantial topographic change with rapid onshore uplift close to the Atlantic coast and simultaneous subsidence of basins on the continental shelves, most likely throughout the Mesozoic.</p><p>We present a review of geophysical data and interpretation of the whole region with emphasis on data relevant for assessing topographic change. We review the available data on topography, bathymetry, density, seismic velocity, and heat flow and present interpretations of the structure and composition of the crust and lithospheric mantle.</p><p>We find that most of the northern North Atlantic Ocean has anomalously shallow bathymetry although it follows the “normal” square-root-of-age dependence, which however is elevated by up-to 2 km. The heat flow variation follows the square-root-of-age dependence, although heat flow is anomalously low on the spreading ridges around and on Iceland. In apparent contrast, exceptionally low seismic velocities are observed along the spreading ridges around and below Iceland. Near-zero free-air gravity anomalies indicate that the oceanic areas are mainly in isostatic equilibrium, whereas anomalously low Bouguer anomalies indicate low density in the uppermost mantle. Anomalously thick oceanic crust is observed along the Greenland-Iceland-Faro Ridge and extending into the Davis Strait. We propose that the anomalous bathymetry is caused by compositional variation in the lithosphere, which indicates that the lithosphere in the ocean may include remnants of continental lithosphere.</p><p>The onshore circum-Atlantic areas show rapid uplift close to the coast with rates up-to 3 cm/yr. This is surprisingly associated with strong positive free-air gravity anomalies which predicts isostatic subsidence. However, negative free-air gravity anomalies in onshore Canada and Bothnian Bay explain recent uplift in the shields as isostatic rebound after glaciation. Archaean lithosphere is everywhere thick in both Greenland and Fennoscandia, Proterozoic areas have thinner lithosphere and Palaeozoic-Mesozoic areas have very thin lithosphere. It is enigmatic that the presumed Archaean-Proterozoic Barents Sea region is submerged and includes deep sedimentary basins.</p>

scholarly journals Response of a low-subsiding intracratonic basin to long wavelength deformations: the Palaeocene–early Eocene period in the Paris Basin

Solid Earth ◽  
2016 ◽  
Vol 7 (1) ◽  
pp. 205-228 ◽  
Author(s):  
J. Briais ◽  
F. Guillocheau ◽  
E. Lasseur ◽  
C. Robin ◽  
J. J. Châteauneuf ◽  
...  
Keyword(s):  
North Atlantic ◽  
Geodynamic Setting ◽  
Paris Basin ◽  
Eurasian Plate ◽  
Massif Central ◽  
Sequence Stratigraphic ◽  
Long Wavelength ◽  
The North ◽  
Pattern Sequence ◽  
The North Atlantic

Abstract. The uppermost Cretaceous to early Palaeogene is a period of major deformations of the western part of the Eurasian plate with prominent basin inversions starting from the Coniacian onwards. These deformations occur in a complex geodynamic setting within both the context of the Africa–Eurasia convergence and the North Atlantic opening. While Mesozoic graben inversions have been extensively studied, particularly in Eastern Europe and the North Sea, more gentle deformations that affect thicker crust areas (intracratonic basins and emerged lands) are not as well documented. The objective of this study is to constrain the exact timing, type, and magnitude of the early Palaeogene deformations affecting the intracratonic Paris Basin and to integrate them at the western European scale. Low-amplitude deformations are attempted through a high-resolution reconstitution of its stratigraphic record based on well-dated outcrops and well-dated wells, and a high number of well-logs that are correlated using the “stacking pattern” sequence stratigraphic technique. Two orders of sequences are identified (third and fourth order) and correlated throughout the basin. Basin geometric and palaeogeographic reconstitutions are based on sediment thickness and facies analysis. Two-dimensional accommodation space measurements were taken in order to quantify the magnitude of the deformations. Three phases of deformation were recognized. 1. An intra-Maastrichtian–pre-Thanetian (59 Ma) deformation, with major uplift and erosion of the Cretaceous strata with two sub-periods of deformation: Maastrichtian–pre-middle-Danian and Upper Danian–pre-Thanetian long-wavelength deformations. This period of major deformation is coeval with Upper Cretaceous/pre-Danian compressive deformations linked to the Africa–Eurasia convergence in southern France and with volcanic activity from the North Atlantic to Massif Central and the Rhenish Shield during the Palaeocene. 2. An early Ypresian (55.1–54.3 Ma) medium-wavelength deformation ( ×  10 km), here reported to be a stress rearrangement related to the onset of the North Atlantic opening. 3. An uppermost Ypresian (49.8 Ma) long-wavelength deformation ( ×  100 km), contemporaneous with flexural compressive deformations in the Aquitaine Basin (Pyrenean deformation), and related to the Iberia–Eurasia convergence.

The Currents of the North Atlantic

1892 ◽  
Vol 34 (872supp) ◽  
pp. 13940-13941
Author(s):  
Richard Beynon
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic
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