GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.3 GNGTS 2023 velocity anomalies at the surface, and we relied on those to model a faster intrusive body within the crust. Estimation of the density distribution in the mantle was obtained using Perple_X software, assuming a standard mantle chemical composition expressed by the work of Tunini et al. (2015). Density of water was set at 1020 kg/m3, and sediment and crustal densities were modeled through an updated version of the Brocher’s equation. The resulting density model was improved using a Least Squares optimization method regularized by the method of pseudo-observations (Sansò, 1996), using as observations the gravity disturbances, synthesized at sea level from the XGM2019e model (Zingerle et al. 2020) and reduced for the effect of topography and the effect of the water. We present the final density model and discuss it in terms of intra-crustal densification and relation to surface magmatic outcrops, finding that correlations can be identified. These demonstrate the presence of deep-seated crustal density variations which relate to geological provinces identified from surface investigations. A further point to discuss is the rheological properties obtainable from the joint velocity and density model and the relation to the inhomogeneous distribution of seismicity. Bibliografia Barton P. J.; 1986: The relationship between seismic velocity and density in the continental crust—a useful constraint?. Geophysical Journal International, 87(1), 195-208. Connolly J. A. D.; 2005: Computation of phase equilibria by linear programming: A tool for geodynamic modeling and its application to subduction zone decarbonation , Earth Planet. Sc. Lett., 236, 524–541, https://doi.org/10.1016/j.epsl.2005.04.033 , 2005. Fairhead J. D.; 2016: Advances in gravity and magnetic processing and interpretation . EAGE Publications. Kaviani A., Paul A., Moradi A., Mai P. M., Pilia S., Boschi L., Rümpker G., Lu Y., Tang Z. and Sandvol E.; 2020: Crustal and uppermost mantle shear wave velocity structure beneath the Middle East from surface wave tomography. Geophysical Journal International, 221(2), 1349-1365. Moritz H.; 1978: Least‐squares collocation. Reviews of geophysics, 16(3), 421-430. Nwozor K. K., Onuorah L. O., Onyekuru S. O. and Egbuachor C. J.; 2017: Calibration of Gardner coefficient for density–velocity relationships of tertiary sediments in Niger Delta Basin . Journal of Petroleum Exploration and Production Technology, 7(3), 627-635. Sampietro D., Capponi M., Mansi A. H., Gatti A., Marchetti P. and Sansò F.; 2017: Space-Wise approach for airborne gravity data modelling . Journal of geodesy, 91(5), 535-545. Sansò F.; 1996: Elementi di teoria della probabilità . Cittàstudi.