Joint inversion of magnetotelluric and seismological observations in the western Borborema Province (NE Brazil): Implications for basin inversion
Araripe Basin; basin inversion; seismological datasets; magnetoteluric datasets; joint inversion
The main goal of geophysical measurements is to obtain reliable information of subsurface rocks and physical properties of fluids. To achieve this goal, different methods try to determine, as accurately as possible, the geometry of fluid-infiltrated strata and rock bodies that are part of the subsurface structure, while other methods focus on obtaining other physical properties. Seismological or magnetotelluric (MT) measurements provide incomplete information when used independently. While seismological methods are used typically to obtain structural information of the subsurface and velocity distribution, MT techniques are a powerful tool to distinguish between rocks containing hydrocarbons and those containing saline water. Combined together, these techniques have the potential to improve considerably the image of the subsurface. This work made use of two joint inversion techniques between geophysical datasets, in order to developed constraints on Earth structure that improved our understanding of the physical processes behind the uplift of the Araripe Basin. Resistivity and S-velocity models were developed that revealed the presence of high-velocities (4.1 - 4.3 km/s) in the lower crust beneath the Araripe Basin interpreted as mafic underplate, as well as the presence of high conductivity (~40 Wm) at mantle levels (~110 km) that coincides with a seismic low velocity zone (4.2 km/s) under the Araripe Basin interpreted as enriched asthenospheric material inherited from Mesozoic rifting processes. Both models provide clear evidence for thinning of the lithosphere beneath the Araripe Basin, consistent with a shallow asthenosphere reported for the region