Banca de DEFESA: DIOGO LUIZ DE OLIVEIRA COELHO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : DIOGO LUIZ DE OLIVEIRA COELHO
DATE: 17/12/2019
TIME: 14:00
LOCAL: Auditório do CCET
TITLE:

Passive-source seismology in the Parnaíba Basin: Implications for cratonic subsidence

KEY WORDS:

Receiver Function; Crustal Structure; Mantle Transition Zone; Cratonic Subsidence; Parnaíba Basin

PAGES: 152
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

In this thesis we present different methodological approaches that characterize the crustal structure and the Mantle Transition Zone in order to elucidate the main geodynamic processes that operate in and under the Parnaíba Basin. Point estimates of crustal thickness and Vp/Vs ratio, together with S-wave velocity profiles, obtained from receiver function analysis at various seismographic stations within the basin show a thick crust near the current depocenter caused by a high-velocity seismic layer located at the crust/mantle boundary. The basin’s crustal structure matches that of Precambrian terrains worlwide and suggests minimal crustal stretching in the east-west direction. Imaging of the Mantle Transition Zone (MTZ) through migration of receptor functions, on the other hand, rules out deep convective processes under the basin as responsible for its cratonic subsidence, as the constrained MTZ thickness remains uniform under the basin. Another finding that rules out vertical asthenospheric flow driving basin subsidence is the shallowing of the 660 km discontinuity under the Cambrian rifts near the Transbrasiliano Lineament. This upwarp is indicative of a thermal anomaly at the base of the Transition Zone, but not at the top where no change is observed. The addition of new crustal and mantle constraints for the Parnaíba Basin represents our main contribution to the present debate on its origin and cratonic evolution, and we expect that they will contribute in the future to unveiling the processes that determined the evolution of this basin over geological time.

BANKING MEMBERS:
Interno - 1451214 - ADERSON FARIAS DO NASCIMENTO
Presidente - 1863578 - JORDI JULIA CASAS
Externo à Instituição - MARCELO SOUSA DE ASSUMPÇÃO - USP
Externo à Instituição - SÉRGIO LUIZ FONTES - ON/MCT
Interno - 349684 - WALTER EUGENIO DE MEDEIROS