Banca de DEFESA: REBECA SEABRA DE LIMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : REBECA SEABRA DE LIMA
DATA : 14/08/2017
HORA: 08:00
LOCAL: Auditório do LGGP II
TÍTULO:

GPR-DIGITAL IMAGING AND MODELING IN MICROBIALITES FROM FAZENDA ARRECIFE, CHAPADA DIAMANTINA (BA), NE BRAZIL

PALAVRAS-CHAVES:

Digital imaging, GPR, Microbialites

PÁGINAS: 70
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

This dissertation involves the digital imaging and modeling of a neoproterozoic microbialite colony from the outcrop of Fazenda Arrecife (BA), using the Ground Penetraring Radar (GPR) method and the application of "attributes". Concomitantly, a survey of repairs and an acquisition of radioactive profiles was applied, allowing the characterization of the sedimentary facies. Petrographic studies and chemical analysis (SEM/EDS and XRF) were used to identify a composition of the stylolithics levels that generate reflections in the GPR sections. The
"Instantantaneous Amplitude" attribute highlighted a microbialite community (low amplitude) which displays different signature pattern. The "Energy" attribute showed a similar result comparing to the "Instantaneous Amplitude", nevertheless, providing a greater visualization of the internal lamination of the columnar microbialite. The "Similarity" attribute emphasized the community boundary. The "Hilbert Trace/Energy" combination showed significant enhancement of the microbial growth boundaries than the "Energy" attribute. The attribute
"Hilbert Trace/Similarity" highlighted the internal structure of the microbial community. The described facies were described the microbialitic facies (MCme, MCm and MCma) and the tempestite facies (Cahm). The petrographic study shows minerals such as limonite and/or siderite, which corroborates with the chemical analysis results. The chemical analysis shows high Fe values to the stylolithic level, which causes the reflections observed in the GPR
sections, due to the electromagnetic contrast between the microbialite (ℇ = 6, 55) and the stylolithic levels (ℇ = 14,2). The 3D solid result properly represents a microbial community. The attribute application to GPR section applied in this dissertation allowed highlight the microbialite features non-observed in the original data. This application can be used in other geologic context.

MEMBROS DA BANCA:
Interno - 1315614 - DAVID LOPES DE CASTRO
Presidente - 1161652 - FRANCISCO PINHEIRO LIMA FILHO
Externo à Instituição - VIRGÍNIO HENRIQUE NEUMANN - UFPE