Banca de DEFESA: LUZIA LINIANE DO NASCIMENTO SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUZIA LINIANE DO NASCIMENTO SILVA
DATE: 07/05/2021
TIME: 14:00
LOCAL: Videoconferencia - https://meet.google.com/gzq-ekza-wds
TITLE:

Holocene records of mixed carbonate-siliciclastic sedimentation of the RN outer shelf

KEY WORDS:

siliciclastics sediments, carbonates; statistics; geochemistry; geomorphological features.

PAGES: 138
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The continental shelf of northeastern Brazil is characterized by a semi-arid climate, warm temperatures, clear waters, low sedimentary input, and mixed sedimentation, carbonatesiliciclastic. In this study, statistical analyzes, mean grain size, sorting, skewness, and kurtosis were applied to 123 superficial sedimentary samples from the outer shelf of Rio Grande do Norte to verify the controlling factors of the sediment distribution. In addition,
geochemical analysis using X-ray diffraction (XRD) methods in 18 samples, X-ray fluorescence (XFR) in 20 samples, scanning electron microscopy, and dispersive energy spectroscopy (SEM / EDS) in 10 samples. Another technique used was digital image processing applied to Landsat 8 / OLI satellite images in order to assess the spatial distribution of the submerged features on the continental shelf between Amazonas and Bahia. The main results demonstrated that the statistical parameters skewness and kurtosis were the ones that most evidenced the distinction between siliciclastic and carbonate sediments from the outer shelf, the chemical compositions differ between siliciclastic facies, composed by Si, Al, Fe, K, Zr, and Ti and the bioclastic facies, consisting of the elements Ca, Sr and Mg. As for digital mapping, reefs occur in waters from 10 to 35 m deep, paleochannels showed a maximum length of 25 km at depths of up to 80 m and underwater dunes have average lengths ranging from 300 to 8 km at depths of 10 to 100 m. Therefore, the integration of these data, showed that the bioclastic sediments come from in situ production and the siliciclastics are relict and derived from continental rocks. The occurrence of reefs, paleovalleys, and dunes indicates similar and favorable conditions for the establishment of these features during the Holocene along the Brazilian continental shelf

BANKING MEMBERS:
Externo à Instituição - ANTÔNIO VICENTE FERREIRA JUNIOR
Presidente - 2042405 - MOAB PRAXEDES GOMES
Externa à Instituição - NARELLE MAIA DE ALMEIDA - IFRN
Externo à Instituição - NATAN SILVA PEREIRA - UNEB
Externa à Instituição - TEREZA CRISTINA MEDEIROS DE ARAÚJO - UFPE