Gravity‐Derived Moho Depth of Egypt: Insights from Lithospheric-Scale Gravity Inversion and Comparison with Global Crustal Models

Gravity‐Derived Moho Depth of Egypt: Insights from Lithospheric-Scale Gravity Inversion and Comparison with Global Crustal Models

Mohammad Shehata^1,2, Hakim Saibi¹

¹Geosciences Department, College of Science, United Arab Emirates University, 15551, Al-Ain, United Arab Emirates

²Department of Geology, Faculty of Science, Port Said University, Port Said 42522, Egypt

 

Reliable constraints on Moho depth are fundamental for understanding lithospheric structure and tectonic evolution, yet estimates across Egypt and northeastern Africa remain uneven in coverage and resolution. Seismic constraints are restricted to discrete locations, while global crustal models mainly capture long-wavelength features and may not resolve crustal thickness contrasts across different tectonic domains. Here we present a country-scale Moho depth model for Egypt derived from GOCE satellite gravity, providing continuous regional coverage for evaluating tectonically controlled crustal thickness variations.

Bouguer gravity anomalies were computed from GOCE satellite gravity data, complemented where appropriate by terrestrial observations, and corrected for topography, bathymetry, and sedimentary cover. Moho geometry was estimated using frequency-domain Parker–Oldenburg iterative inversion incorporating laterally variable crust–mantle density contrasts derived from the CRUST1.0 model, allowing spatial variations in crustal composition and thickness to be explicitly accounted for (Shehata and Mizunaga, 2022). The resulting Moho model reveals systematic crustal thickness variations that closely correspond to Egypt’s tectonic architecture, with shallow Moho depths (~18–22 km) beneath extensional domains associated with Red Sea rifting, intermediate depths (~28–34 km) in transitional zones such as the Nile Delta and Sinai, and thick crust (>40–43 km) across the Western Desert and southern Egypt. Sharp lateral Moho gradients delineate boundaries between these regimes, indicating localized strain accommodation during rift development. Comparison with CRUST1.0 (Laske et al., 2013), GEMMA (Reguzzoni et al., 2013), and the seismic-based Moho compilation of Tugume et al., 2013) shows overall agreement at long wavelengths, while localized deviations occur in rifted and transitional regions due to differences in data resolution and methodological sensitivity. These results demonstrate that tectonic regime exerts a first-order control on Moho depth beneath Egypt and highlight the value of GOCE-based gravity inversion for improving lithospheric characterization in regions of limited seismic coverage.

References

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Reguzzoni, M., Sampietro, D., Sansò, F., 2013. Global Moho from the combination of the CRUST2. 0 model and GOCE data. Geophys. J. Int. 195, 222–237.

Shehata, M.A., Mizunaga, H., 2022. Moho depth and tectonic implications of the western United States: insights from gravity data interpretation. Geosci. Lett. 9, 23.

Tugume, F., Nyblade, A.A., Julia, J., Van der Meijde, M., 2013. Crustal shear wave velocity structure and thickness for Archean and Proterozoic terranes in Africa and Arabia from modeling receiver functions, surface wave dispersion, and satellite gravity data. Tectonophysics 609, 250–266.