3-D density model for the lithosphere of Europe: construction method and preliminary results

Yegorova, Tamara; Kozlenko, V. G.; Павленкова, Н. И.

doi:10.1111/j.1365-246x.1995.tb06445.x

Cited by 15 publications

(20 citation statements)

References 33 publications

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“…Regions of relatively light upper mantle have been distinguished beneath the eastern and northwestern parts of the East European Platform. A heavier upper mantle has been outlined below the Alps, the Calabrian Arc, the Caucasus and the South Caspian Depression (Yegorova et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional gravity modelling of the European Mediterranean lithosphere

Yegorova¹,

Kozlenko²,

Павленкова

1997

Geophysical Journal International

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Residual gravity anomalies characterizing the density heterogeneities in the upper mantle of the Alpine belt of Western Europe are determined. Residual anomalies were calculated on a 1" x 1" grid by subtracting the gravity effect of the density model for the Earth's crust from the observed gravity field. Our 3-D density model consists of two regional layers of varying thicknesses with a lateral variation in average density: the sedimentary cover and the crystalline crust. Offshore, the model is supplemented by a sea-water layer. This 3-D density model is based on a generalized velocity model represented by structure maps of the main seismic horizons (the 'seismic' basement and the Moho boundary) and a map of the average P-wave velocity in the consolidated crust. The density distribution within the model layers was obtained using the correlation functions between P-wave velocity and density. For sediments, sediment consolidation with depth was taken into account. The gravity effect of the model, approximated by parallelepipeds 1" x 1" in planar size, was calculated by a program designed for solving 3-D gravity problems. The program takes into account the spherical configuration of the Earth. This method also permits the estimation of the isostatic state of the crust. A mantle origin of residual gravity anomalies is confirmed by their close correlation with upper-mantle velocity heterogeneities, established by both seismic-tomography and thermal-regime data. The residual gravity field is inverted into the distribution of anomalous density within the uppermost mantle layer (between the Moho and a bottom level at 200 km depth). The most important anomalies are the high-density domains caused by the thick lithosphere of the Adriatic plate and by the lithosphere 'roots' beneath the Alps and the Calabrian Arc. Negative density anomalies over the Pannonian Basin and the Western Mediterranean basins reach -0.04 to -0.05 x lo3 kg m-3 due to thermal expansion of the asthenosphere.

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Section: Introductionmentioning

confidence: 99%

Three-dimensional gravity modelling of the European Mediterranean lithosphere

Yegorova¹,

Kozlenko²,

Павленкова

1997

Geophysical Journal International

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“…It was proved that density anomalies in the crust are compensated by the upper mantle in all geotectonic units studied except in the Alpine Belt. With the observed correlation between gravity effect of the crust and traveltimes of P ‐waves to the Moho boundary (Yegorova et al 1995), the distribution of residual gravity anomalies of mantle origin (without direct gravity effect calculations) has been obtained. Comparing the latter with both the data on velocity heterogeneities in the upper mantle and the distribution of terrestrial heat flow, we concluded a density decrease of the upper mantle below most of Western Europe and the existence of high density domains in the lithosphere below the Caucasus—South‐Caspian region and the Alps (Yegorova et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Lithosphere structure of Europe and Northern Atlantic from regional three-dimensional gravity modelling

Yegorova

2002

Geophysical Journal International

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Summary Large‐scale 3D gravity modelling using data averaged on a 1° grid has been performed for the whole European continent and part of the Northern Atlantic. The model consists of two regional layers of variable thickness—the sediments and the crystalline crust, bounded by reliable seismic horizons—the ‘seismic’ basement and the Moho surface. Inner heterogeneity of the model layers was taken into account in the form of lateral variation of average density depending on the type of geotectonic unit. Density parametrization of the layers was made using correlation functions between velocity and density. For sediments, sediment consolidation with depth was taken into account. Offshore a sea water layer was included in the model. As a result of the modelling, gravity effects of the whole model and its layers were calculated. Along with the gravity modelling an estimation of isostatic equilibrium state has been carried out for the whole model as well as for its separate units. Residual gravity anomalies, obtained by subtracting the gravity effect of the crust from the observed field, reach some hundred mGal (10−5 m s−2) in amplitude; they are mainly caused by density heterogeneities in the upper mantle. A mantle origin of the residual anomalies is substantiated by their correlation with the upper‐mantle heterogeneities revealed by both seismological and geothermal studies. Regarding the character of the mantle gravity anomalies, type of isostatic compensation, crustal structure, age and supposed type of endogenic regime, a classification of main geotectonic units of the continent was made. As a result of the modelling a clear division of the continent into two large blocks—Precambrian East‐European platform (EEP) and Variscan Western Europe—has been confirmed by their specific mantle gravity anomalies (0 ÷ 50 × 10−5 m s−2 and −100 ÷−150 × 10−5 m s−2 correspondingly). This division coincides with the Tornquist–Teisseyre Zone (TTZ), marked by a gradient zone of mantle anomalies. In the central part of the EEP (over the Russian plate) an extensive positive mantle anomaly, probably indicating a core of ancient consolidation of the EEP, has been distinguished. To the west and to the east of this anomaly positive mantle anomalies occur, which coincide with a deep suture zone (TTZ) and an orogenic belt (the Urals). Positive mantle anomalies of the Alps, the Adriatic plate and the Calabrian Arc, correlating well with both high‐velocity domains in the upper mantle and reduced temperatures at the subcrustal layer, are caused by thickened lithosphere below these structures. Negative mantle anomalies, revealed in the Western Mediterranean Basin and in the Pannonian Basin, are the result of thermal expansion of the asthenosphere shallowing to near‐Moho depths below these basins.

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“…However, the effect caused by these crustal factors creates small local anomalies. We therefore presume that large residual anomalies are caused mainly by mantle heterogeneities (YEGOROVA et al, 1995).…”

Section: Modelling Resultsmentioning

confidence: 98%

“…The map uses Bouguer anomalies on land and free-air anomalies offshore, averaged over a 1°×1°grid. Portion of the map of Europe and North Atlantic (YEGOROVA et al, 1995). Contour interval 10 × 10 −5 m s −2 .…”

Section: Structure Of the Model And Initial Datamentioning

confidence: 99%

“…1) because they are compensated isostatically by crustal inhomogeneities. To estimate subcrustal density heterogeneities, residual anomalies obtained by subtracting the gravity influence of the earth's crust from the observed gravity field, were used (ARTEMJEV et al, 1994;YEGOROVA et al, 1995). The correct method for estimating subcrustal density heterogeneities is large-scale gravity modelling based on the 3-D mass distribution of a simplified crustal model.…”

Section: Introductionmentioning

confidence: 99%

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Large-scale 3-D Gravity Analysis of the Inhomogeneities in the European-Mediterranean Upper Mantle

Yegorova

Kozlenko

1998

Pure and Applied Geophysics

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Methods and the results of estimating the anomalies characterising the density inhomogeneities in the European-Mediterranean upper mantle are described. These anomalies were obtained by subtracting the gravity effect of a crustal density model derived from seismic velocities from the observed gravity field averaging over an area of 1°×1°. The 3-D density model of the study region comprises two regional layers of varying thickness with lateral variation of average density: the sedimentary cover and the crystalline crust. The average densities for model layers were evaluated by using a velocity/density conversion function and taking into account sediment consolidation with depth. Clear correlation between residual gravity anomalies and both velocity heterogeneities and thermal regime data of the upper mantle has been revealed. An agreement of positive anomalies over the Alps, the Adriatic plate and the Calabrian Arc with high velocity domains in the upper mantle and reduced temperatures at the subcrustal layer are caused by lithospheric ''roots'' and thickened lithosphere below these structures. Gravity residual lows, revealed over the Western Mediterranean Basin and Pannonian Basin, are in correspondence with both low velocities and high temperatures in the upper mantle. These anomalies are the result of the presence of asthenosphere in shallow near-Moho depths below these basins.

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3-D density model for the lithosphere of Europe: construction method and preliminary results

Cited by 15 publications

References 33 publications

Three-dimensional gravity modelling of the European Mediterranean lithosphere

Three-dimensional gravity modelling of the European Mediterranean lithosphere

Lithosphere structure of Europe and Northern Atlantic from regional three-dimensional gravity modelling

Large-scale 3-D Gravity Analysis of the Inhomogeneities in the European-Mediterranean Upper Mantle

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