Banca de DEFESA: LUZIA LINIANE DO NASCIMENTO SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LUZIA LINIANE DO NASCIMENTO SILVA
DATA : 02/03/2017
HORA: 14:00
LOCAL: Sala 1 PPGG
TÍTULO:

Geomorphology and Sedimentology of the reefs of outer continental shelf, North of RN 

PALAVRAS-CHAVES:

outer shelf, reefs, sedimentology, geomorphology, sonography.

PÁGINAS: 89
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

The northern outer continental shelf of the Rio Grande do Norte is a zone of physiographic, sedimentological transition and of physical and biological oceanographic processes marked by the eustatic variations of the Quaternary. The sedimentary evolution of these transition areas can be revealed through geomorphological and sedimentological data, for which the sonography method and the bottom sediment technique have been applied in geological and habitat mapping. In this study the side scan sonar was used to map an area of 413 km², parallel to the breaking of the platform, between Macau (to the north), and Ponta do Mel (to the east). As a result, 12 backscatter patterns (P1 to P12) were associated with 11 sedimentary facies (bioclastic and siliciclastic faceis), patches reefs that extend for more than 30 km parallel to the coast, and the paleovale of the Açu river that crosses all the region of the platform under study.The bioclastic sand facies with granules are predominant, related to the backscattering pattern P11, and is the main faceis responsible for the high percentage of organic matter and carbonate contents.The characterized sedimentary facies show a relationship between their distribution and the reefs mapped, indicating a migration of sediments to the west of the studied area, where the finest sediments are concentrated within the valley and among the reefs. Around the incised valley occurs the highest levels of carbonate and organic matter, this may be due to the geomorphological barrier formed by it that favors the circulation and the permanence of the nutrients in this region. However, this region does not concentrate the largest amounts of reefs, this may indicate excess nutrients capable of disfavoring its growth due to the competition for space generated with the sponges. The reefs were classified in patches reefs and elongated in the NW-SE direction, aligned for several kilometers. They are located between 30.68 - 33.91 m depth, with average values of 5 m for height, 135 m for length and 26 m for diameter. Reef alignment may be evidence of substrates that represent features subject to the effect of waves and tides, such as ancient coastal lines. The distribution of the sedimentary facies suggests that the sedimentation of the outer platform is constituted under a hydrodynamic regime of variable energy. Additionally, it was observed that the reef field serves as a trap for the sediments, this makes sedimentation distinct inside and outside the reef field. Thus, the sedimentation of regions above 30 m of depht are essentially bioclastic, and represent the most reef-rich portion of the shelf.

MEMBROS DA BANCA:
Presidente - 2042405 - MOAB PRAXEDES GOMES
Externo à Instituição - TEREZA CRISTINA MEDEIROS DE ARAÚJO - UFPE
Externo à Instituição - WERNER FARKATT TABOSA - UNI-RN