Joint inversion of surface wave and gravity data reveals subbasin architecture of the Congo Basin

Abstract

We investigated the architecture of the greater Congo Basin, one of the largest and least-well-studied sedimentary basins on any continent. Seismograms from a large number of M > 4.5 earthquakes within and surrounding the African plate were used to make event-to-station Rayleigh wave group velocity measurements between periods of 5 and 100 s. Group velocities for discrete periods across the basin, obtained by inverting the event-station measurements, were jointly modeled with gravity data to obtain a three-dimensional S-wave and density model of the basin. The model corroborates the existence of two previously suggested subbasins, one to the north and one to the south, each ~8 km deep and separated by an east-west structural high. Our results favor a salt tectonics origin for the structural high but cannot rule out uplifted basement rock. The northern subbasin is offset to the west from the southern subbasin, consistent with previous studies suggesting sinistral motion along basement faults during periods of transpressional tectonics in late Neoproterozoic–early Paleozoic times.

Africa's Crustal Architecture Inferred From Probabilistic and Perturbational Inversion of Ambient Noise: ADAMA

“…The outline of the Congo basin is taken from Raveloson et al. (2015, 2021). For a view of the starting model used for the update and standard deviation of the final shear‐velocity model see Figures S5a and S6 in Supporting Information .…”

“…We anticipate that such efforts , 2015). We contrast this with Moho models based on joint inversion with other geophysical methods to obtain thermo-compositional models of the African lithosphere (Afonso et al, 2022;Globig et al, 2016;Haas et al, 2021;Raveloson et al, 2021).…”

“…In what follows, we review the current state of seismic models of the African crust (Begg et al., 2009; Crosby et al., 2010; Finger et al., 2022; Raveloson et al., 2015). We contrast this with Moho models based on joint inversion with other geophysical methods to obtain thermo‐compositional models of the African lithosphere (Afonso et al., 2022; Globig et al., 2016; Haas et al., 2021; Raveloson et al., 2021).…”

“…Other regional models (Borrego et al, 2018;Chambers et al, 2019;Eshetu et al, 2021;Fadel et al, 2020;S. Kim et al, 2012;Malory et al, 2022;Wang et al, 2019;White-Gaynor et al, 2021) do a similar job at providing improved depth and spatial resolution, Raveloson et al (2015Raveloson et al ( , 2021. For a view of the starting model used for the update and standard deviation of the final shear-velocity model see Figures S5a and S6 in Supporting Information S1.…”

Africa’s Crustal Architecture Inferred from Probabilistic and Perturbational Inversion of Ambient Noise: ADAMA

“…For seismic methods, like receiver functions, that improve sensitivity right underneath the seismic station then depth resolution of crust and mantle discontinuities will only be possible when stations are co-located with regions with high resolution from surface wave studies. In what follows, we review the current state of seismic models of the crust (Begg et al, 2009;Crosby et al, 2010;Raveloson et al, 2015;Finger et al, 2022), we contrast this with Moho models based on joint inversion with other geophysical methods of obtain thermo-compositional models of the African lithosphere (Globig et al, 2016;Raveloson et al, 2021;Haas et al, 2021;Afonso et al, 2022).…”