Banca de QUALIFICAÇÃO: KHALIL BOW LTAIF GARCIA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : KHALIL BOW LTAIF GARCIA
DATE: 18/10/2023
TIME: 14:00
LOCAL: Videoconferência / Canal Youtube PPGG
TITLE:

GEOMORPHOLOGY OF RIO GRANDE DO NORTE OUTER AND QUATERNARY SEA LEVEL FLUCTUATIONS

KEY WORDS:

Sea Level Fluctuations, Açu Reef, Quaternary

PAGES: 50
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

Modern outer shelves are transitional environments between the continental
shelf and ocean basins. Sea level fluctuations directly affect this region, shaping it
and creating geomorphological records. The study area is located on the northern
outer shelf of Rio Grande do Norte adjacent to Macau City. Numerous evidences of
paleo sea level are found on the shelf such as: the Açu Incised Valley, submerged
dunes, beachrocks, terraces and reefs. The goal of this work is to map a field of reefs
called Açu Reef that populated both west and east banks of the Açu Incised Valley,
covering an area of 100 km². The present work aims to understand the role of the

shelf's physiography, the antecedent lithology, the role of the Incised Valley in the
distribution and formation of the Açu Reefs and the correlations between the reefs
and the last deglacial event in the Holocene. Through multibeam bathymetry data, it
was possible to map an area of 33 km² with the occurrence of reefs between 25-50 m
isobaths. The patch reefs are on average 4 m high and are positioned in two well-
marked terraces: T1 at 30 m and T2 at 40 m. Both located behind to barrier reef
lineaments that provide the formation of a lagoon for their development. Correlating
its distribution and sea level curves at low latitudes, it is observed that the best
conditions for reef formation occurred between 11-9 kyr BP. This Period represents
the final phase of the Meltwater Pulse 1B which is characterized by a slowdown in
sea level rise. A large difference in formation is noted between the reefs on the west
bank and east bank of the Açu River, possibly due to tidal, current, wind and even
structural influences. Thus, three sectors can be identified, a dune field to the west of
the incised valley, an estuary at the old river mouth and a barrier island system to the
east of the valley, which brings complexity to this area

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