Banca de QUALIFICAÇÃO: RICARDO DE SOUZA RODRIGUES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : RICARDO DE SOUZA RODRIGUES
DATE: 27/11/2020
TIME: 08:30
LOCAL: Videoconferencia - https://cutt.ly/6fcqwHK
TITLE:

Tectonic evolution of transform margin: Contribution of structural mapping (onshore)
and physical modeling of the Brazilian Equatorial Margin.

KEY WORDS:

Brittle deformation; physical modeling; Brazilian Equatorial Margin.

PAGES: 84
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

During the post-Phanerozoic time, the Borborema Province underwent several deformational events that resulted in the fragmentation of the Western Gondwana Supercontinent and the installation of the Brazilian Equatorial Margin. Located in the easternmost segment of this margin, the Potiguar and Ceará basins, do not show outcropping lithologies from the pre-rupture interval, and the records of these deformations lie in their crystalline basement. Thus, we performed a multiscale structural analysis, using different approaches, in select sites of basin’s basement of these basins to get a better understanding of the evolution of this margin. We describe different systems of fracture that affected the crystalline substrate. They were related to four distinct deformational events along the time: (i) Late-Brazilian, (ii) Juro-cretaceous, (iii) Aptian and (iv) Oligocene-Miocene. Dry fractures and/or silica(chalcedony) filled ones, oriented E-W to WNW-ENE besides the brittle reactivation of the Brazilian-age shear zones characterize the late-Brazilian deformation under an E-W to WNW-ENE compression field. The NW-SE extension during the Juro-Cretaceous is represented by NE-SW joints and basic dikes oriented E-W to NE-SW related to Rio Ceará Mirim volcanism. Extensional shearing and hybrid fractures, (dry or filled with chalcedony, iron oxide or calcite) characterize the E-W dextral transtension during the Aptian. The records of the N-S to NNW-SSE compression during the Oligocene-Miocene, are represented by a swarm of N-S joints and dextral NNW-SSE transtensional fractures (dry or filled with iron oxide). The substrate rheology and orientation of previous heterogeneities, in relation to the stress field are factors that influenced the type of structure generated. Physical models of transform margin were performed using different granular materials to represent the substrate. Models with natural quartz sand and aluminum oxide, and those combining quartz sand and silicone, produced wider damage zones and transtensional sites. For their turn, models with glass microbead, plaster and clay produced narrower damage zones once deformation was localized generating shallow depocenters and a few compressional structures. Along oblique segments, like the NW-SE trending ones of the Brazilian Equatorial Margin, en echelon grabens and pull-apart basins can develop. Although the installation of the equatorial margin occurred orthogonally to the previous anisotropies, in the Ceará basin, the Trans-Brazilian Lineament contributed to the tectonic compartmentalization of its sub-basins. So transtension/extension has dominated in the east side of the lineament and trantension/compression on its west side.

BANKING MEMBERS:
Presidente - 1217847 - FERNANDO CESAR ALVES DA SILVA
Interno - 350640 - FRANCISCO HILARIO REGO BEZERRA
Interna - 1149363 - VALERIA CENTURION CORDOBA
Externo ao Programa - 2490483 - ALEX FRANCISCO ANTUNES