Banca de QUALIFICAÇÃO: KHALIL BOW-LTAIF GARCIA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : KHALIL BOW-LTAIF GARCIA
DATE: 16/03/2020
TIME: 09:00
LOCAL: Sala 2 - PPGG
TITLE:

Geomorphology of the Rocas Atoll Shelf 

KEY WORDS:

Geomophology; Rocas Atoll; Reefs, Terraces.

PAGES: 25
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

Tropical atolls are shallow oceanic regions of carbonate sedimentation, surrounded by reefs, with a shallow internal lagoon and generally grow on seamounts, harboring great biodiversity. The Rocas Atoll is located in the western portion of the South Atlantic Ocean, aligned with the seamounts of the Fernando de Noronha fracture zone. This work presents the shelf physiography at depths between 5 and 120m, the distribution of morphological features (reefs, terraces), and the coverage of carbonate sediments. In October 2018, a bathymetric survey was carried out on the Rocas Atoll shelf using a single-beam system (ODON Hydrotrack). Bathymetric data were filtered using the HYPACK 2014 software and modeled on the ArcGIS software, generating a digital terrain model, besides bathymetric maps and profiles. The data revealed a flattened shelf with a depth average of 20 m and an irregular shelf break with depths between 50 m and 70 m. Two main features have been identified: reefs and terraces. The reefs have been mapped in isolated or grouped forms, ranging from 1 to 5 m in height; the terraces are associated with the edge of the platform with a remarkable expression at depths of 25 and 40 m. The reefs and terraces of the Rocas Atoll were compared with reefs and terraces of the external north platform of Rio Grande do Norte, observing a conciliation between the depths of occurrence, distribution and dimensions of the features. These morphological marks from Rocas Atoll and RN shelf suggest that the sea level and ocean circulation influenced the carbonate system development and preservation, and allowed consistent relations between these two regions.

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