Geofísica

O Cráton Amazônico é considerado uma das maiores áreas cratônicas do mundo, com cerca de quatro milhões de quilômetros quadrados e representa um componente essencial nas reconstruções paleogeográficas. A determinação de polos paleomagnéticos de referência é de extrema importância para a definição da paleogeografia de supercontinentes e para o entendimento dos processos de amalgamação e fragmentação do ciclo continental.

In this work, the thermochemical convection in the terrestrial mantle and the relative displacement between the asthenosphere and lithosphere were simulated to study the mantle flow around cratonic keels. These processes are probably related to the preferential orientation of seismic anisotropy in the upper mantle.

Gravimetric and seismological data will be used to derive 3D models of density and S-wave velocity for the Pantanal, Paran´a and Chaco-Paran´a basin regions, through the joint inversion of these two types of geophysical data. Initially, for the gravimetric case, we will combine satellite data (GOCE) with freshly collected terrestrial data in the Paraguay region to increase the resolution of the gravimetric model.

In this work we evaluate different strategies for the model update inside a FWI algorithm. It is know that the S wave velocity parameter is the one with greater sensitivity in a data covered by surface waves. The studied strategies, however, attempt to recover the P wave velocity and the density models in different ways. We compared the pure optimization through a conjugate gradient algorithm with the direct calculation assuming a constant Poisson ratio and by Gardner equation. The results show good performance of the both methodologies in simple 1D models.