Banca de DEFESA: ADRIANE GONCALVES DE ARAUJO NUNES RANGEL

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ADRIANE GONCALVES DE ARAUJO NUNES RANGEL
DATA : 10/06/2019
HORA: 09:00
LOCAL: Instituto de Geociências
TÍTULO:

ANTECEDENT TOPOGRAPHY CONTROLS PRESERVATION OF LATE QUATERNARY TRANSGRESSION RECORD AND CLINOFORM GEOMETRY: THE SÃO FRANCISCO DELTA (EAST-NORTHEASTERN BRAZIL)

PALAVRAS-CHAVES:

wave-dominated delta; sea-level changes; seismic stratigraphy

PÁGINAS: 55
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
SUBÁREA: Geologia
ESPECIALIDADE: Estratigrafia
RESUMO:

The present study used shallow high-resolution seismic surveys to characterize the architecture and stratigraphic evolution of the last depositional sequence of the São Francisco Delta (SFDS), deposited during the late Pleistocene/Holocene. The SFDS accumulated in a bathymetric depression of the continental shelf associated with the São Francisco canyon head. The existence of this depression resulted in additional accommodation space measuring several tens of meters, which allowed the accumulation of a continuous stratigraphic record of eustatic sea-level rise since the Last Glacial Maximum on one of the shallowest and narrowest continental shelves in the world. Six major seismostratigraphic units were individualized. The lower units (Su1, Su2 and Su3) accumulated around the head of the canyon, limited by the walls of the bathymetric depression. Su1 was possibly drowned by MWP1A. Units Su2 and Su3 accumulated over the ensuing period of reduced rates of eustatic sea-level rise between the end of MWP1A and the Younger Dryas (YD). The top of Su3 transitions laterally to a wave-cut terrace engraved in the walls of the bathymetric depression. This terrace is located between 55 and 60 m below present sea level, and probably marks shoreline position during the YD. Su3 was drowned by MWP1B, as indicated by sediment wedges (Su6) that buried the top of this unit in the lateral portions of the bathymetric depression. Su4 was deposited still within a coastal embayment, during a period of low sea-level rise rates after MWP1B. Su4 was apparently drowned by MWP1C around 8.4 ka BP, marking the formation of the maximum flooding surface. The deposit of Su5, which corresponds to the most recent unit of the delta, only took place after the stabilization of eustatic sea level that began in 8-7.5 ka BP. This study demonstrated how variations in eustatic sea-level rise rates combined with antecedent local morphology favored the creation of a continuous sedimentary record of Holocene transgression.

MEMBROS DA BANCA:
Externo à Instituição - HORTENCIA MARIA BARBOZA DE ASSIS
Presidente - 286023 - JOSE MARIA LANDIM DOMINGUEZ
Externo ao Programa - 1365427 - JUNIA KACENELENBOGEN GUIMARAES