Banca de DEFESA: GILBERTO DA SILVA LEITE NETO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GILBERTO DA SILVA LEITE NETO
DATE: 02/12/2019
TIME: 14:30
LOCAL: Auditório do departamento de geofísica
TITLE:

Numerical modeling of flexural stresses in Northeast Brazil

KEY WORDS:

Flexural Stresses; Numerical Stress Modeling; Stress Superposition; Stresses in Northeast Brazil; Reactivation of Pernambuco Shear Zone.

PAGES: 147
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

 In this dissertation, we model the contribution of the stresses generated by the topography and density heterogeneities in the stress field of NE Brazil, and the interplay between these and regional stresses. Our model consists of a horizontally-layered elastic slab (the lithosphere) that floats above an inviscid fluid (the asthenosphere), where the surface load is generated by the topography and bathymetry, and the internal loads are calculated from the Bouguer anomalies. The deviatoric flexural stresses are calculated in the Fourier domain. Our results showed local flexural stresses with magnitudes comparable to those of the tectonic plate-wide stresses, and mainly controlled by the long-wavelenghts Bouguer anomalies. Scenarios for the total stress field were calculated by superposing different values for an E-W-oriented regional compression. We predict the stress axes orientations and stress regimes for the equatorial margin and for the Pernambuco Shear Zone (PESZ) region, although we highlight the importance of spreading stresses, not considered in this work, in rotating the maximum horizontal compression (SHmax) predictions. The prediction of stress regime and stress axes orientation in PESZ using low to zero regional compression suggest that a decoupling of the shallow stresses from the plate-wide stresses might occur in this region. Other possible explanation found was that the spreading stresses might counterbalance the regional stresses. We conclude that the superposition of principally flexural and plate-wide stresses explains reasonably the observed stress regimes and SHmax orientations in great part of NE Brazil. Furthermore, flexural stresses are playing an important role in the reactivation of the PESZ, possibly controlling the stress field.

BANKING MEMBERS:
Interno - 1315614 - DAVID LOPES DE CASTRO
Externo à Instituição - HELENO CARLOS DE LIMA NETO - UnP
Presidente - 583.103.478-04 - JOAQUIM MENDES FERREIRA - UFRN