ANALISE DA ESTRUTURA CRUSTAL NA FAIXA RIBEIRA (ENTRE AS PROVINCIAS DO CRATON SAO FRANCISCO E DA BACIA DO PARANA) UTILIZANDO METODOS SISMOLOGICOS

Abstract

The geological context of the study area includes the Southeast of Brazil Continental Rift, covered by polycyclic terrains from the south of the Ribeira Belt. Twenty-four broadband temporary seismographic stations were installed along three profiles, two perpendicular to the coast and one parallel, the interstation distance is approxima- tely 20 km. The main goal is determine the crustal structure and highlight the velocity discontinuities in order to better understand the regional geological fra- mework. An effort has been made to ensure data quality of the temporary stations records. Tests with the P wave arrival time and noise level help to localize some errors in database. The receiver function method has been applied to observe the in- ner crustal discontinuities below each station and, posteriorly, to compute the Moho depth. The results of the Receiver Functions indicate that the Moho depth decrea- ses from the inner part of the continent towards the coastal area, from 40 km to 33 km depth. Rayleigh wave group velocities are measured by the cross-correlation of ambient noise recorded at the temporary stations. The group velocities were used to determine the shallow crustal structures. The maps of Rayleigh wave group velocity are consistent with the shallow crustal structures described in the literature. The study highlights the advantages of using several methods to characterize the crustal geological framework.