Spatial and Spectral Analysis of Refined Gravity Data for Modelling the Crust–Mantle Interface and Mantle-Lithosphere Structure

Abstract

We analyse spatial and spectral characteristics of various refined gravity data used for modelling and gravimetric interpretation of the crust-mantle interface and the mantle-lithosphere structure. Depending on the purpose of the study, refined gravity data have either a strong or weak correlation with the Moho depths (Moho geometry). The compilation of the refined gravity data is purely based on available information on the crustal density structure obtained from seismic surveys without adopting any isostatic hypothesis. We demonstrate that the crust-stripped relative-to-mantle gravity data have a weak correlation with the CRUST2.0 Moho depths of about 0.02. Since gravitational signals due to the crustal density structure and the Moho geometry are subtracted from gravity field, these refined gravity data comprise mainly the information on the mantle lithosphere and sub-lithospheric mantle. On the other hand, the consolidated crust-stripped gravity data, obtained from the gravity field after applying the crust density contrast stripping corrections, comprise mainly the gravitational signal of the Moho geometry, although they also contain the gravitational signal due to anomalous mass density structures within the mantle. In the absence of global models of the mantle structure, the best possible option of computing refined gravity data, suitable for the recovery/refinement of the Moho interface, is to subtract the complete crust-corrected gravity data from the consolidated crust-stripped gravity data. These refined gravity data, that is, the homogenous crust gravity data, have a strong absolute correlation of about 0.99 with the CRUST2.0 Moho depths due to removing a gravitational signal of inhomogeneous density structures within the crust and mantle. Results of the spectral signal decomposition and the R. Tenzer (&) Á V. Gladkikh subsequent correlation analysis reveal that the correlation of the homogenous crust gravity data with the Moho depths is larger than 0.9 over the investigated harmonic spectrum up to harmonic degree 90. The crust-stripped relative-to-mantle gravity data correlate substantially with the Moho depths above harmonic degree 50 where the correlation exceeds 0.5.

Comparative analysis of Vening-Meinesz Moritz isostatic models using the constant and variable crust-mantle density contrast – a case study of Zealandia

“…Kaban et al (1999) demonstrated that the isostatic compensation does not take place only within the Earth crust but essentially also within the lithospheric mantle. This finding was later also confirmed by Kaban et al (2004) and Tenzer et al (2009Tenzer et al ( , 2012. These phenomena thus somehow limit a realistic estimation of the Moho parameters based on using only gravity data.…”

Isostatic Crustal Thickness Under The Tibetan Plateau And Himalayas From Satellite Gravity Gradiometry Data

“…The evaluation of δg cs from the gravity disturbance δg is based on applying the topographic and stripping gravity corrections due to major known anomalous crustal density structures. These refined gravity data should have (theoretically) a maximum correlation with the Moho geometry (Tenzer et al 2012b). However, these gravity data still comprise the long-wavelength gravity signal of unmodelled heterogeneities within the lithospheric mantle and the asthenosphere (including the core-mantle boundary zone) as well as uncertainties within the crustal model.…”

“…The consolidated crust-stripped gravity T gradient is obtained from the corresponding gravity gradient component Trr after applying the topographic and crust density contrasts stripping gravity gradient corrections. The computation is realized according to the following scheme (Tenzer et al 2012b) (B.1) where and V are, respectively, the gravitational gradients generated by the topography and density contrasts of the ocean (bathymetry), ice, sediments and remaining anomalous density structures within the consolidated (crystalline) crust.…”

3D gravity interpretation of the pre-Tertiary basement in the intramontane depressions of the Western Carpathians: a case study from the Turiec Basin

“…Stripping is often applied in geophysical studies, on global or regional scale, to unmask the signal of unknown sources, when the signal of known sources/structures can be computed (e.g. Vajda et al 2008;Tenzer et al 2009Tenzer et al , 2012a. Stripping is particularly useful in geophysical and geological investigations of the basement and the deep-seated structure beneath sedimentary basins (e.g.…”