Banca de QUALIFICAÇÃO: ALINE CRISTINE TAVARES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ALINE CRISTINE TAVARES
DATA : 24/04/2019
HORA: 15:00
LOCAL: Sala 1 - PPGG
TÍTULO:

The Romanche fracture zone in the Equatorial margin of Brazil: implications for transform margin evolution

PALAVRAS-CHAVES:

Equatorial Atlantic; Northeastern Brazil; Transform Margin; Divergent Margin; Hyperextended Margin; Fracture Zone; Romanche

PÁGINAS: 41
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

This work addresses the crustal segmentation of the Brazilian Equatorial Margin controlled by Precambrian shear zones and Romanche Fracture Zone, using a combination of satellite and marine gravity anomalies and reflection seismic data. The interpreted data allowed the determination of the structure of the continent-ocean crust by a 2D gravity modeling constrained by seismic data. A simplified evolution model of the Brazilian Equatorial Margin is proposed, involving dextral strike-slip plate motion along the Romanche Fracture Zone in an oblique margin transform setting. South America and Africa were rifted as an oblique margin following angles of 26°-30° in relation to the E-W-striking transform fault from the Barremian (~129 Ma) to the late Aptian (~115 Ma). Shearing between these continental blocks ceased with the appearance of the first oceanic crust in the Albian (~110 Ma). Importantly, the geometry and orientations of early oceanic spreading centers followed continental breakup  and were oblique to the transform. The spreading centers north and south of the Romanche Fracture Zone rotated clockwise and became orthogonal to the transform at isochron 34 (Santonian; ~83.5 ± 8 Ma), an event in which the fracture zone reached its passive stage. As a result of this same event, the present-day Brazilian Equatorial margin is controlled by NW-SE- and E-W-trending structures. The former is related to the spreading centers formed during the first generation of oceanic crust on the margin, while the latter corresponds to the sites where the fracture zone intercepts the continental shelf. Our results indicate that the Romanche Fracture Zone forms well-defined ridges in the Equatorial Atlantic, where it rises up to ~ 2.5 km above surrounding basins. These ridges and a series of NW-SE oriented seamounts prevented the deposition of a significant volume of sediment sourced from the continent, acting as a topographic barrier. Neotectonic reactivation of the fracture zone along the continental- oceanic lithospheric boundary indicates that the Romanche Fracture Zone is a long-lived fault

MEMBROS DA BANCA:
Presidente - 1315614 - DAVID LOPES DE CASTRO
Interna - 2218779 - HELENICE VITAL
Interno - 219.901.818-05 - YOE ALAIN REYES PEREZ