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Previous issue date: 2011-02-08 / The study of Brazilian sedimentary basins concentrates on their rift phase, whereas
the Post-rift phase has been considered a tectonic quiescent period. The post-rift
sequence of the Potiguar Basin, in the far northeastern Brazil, was once considered
little deformed, however several studies have shown how that it was affected by
major fault systems. The purpose of this thesis is to characterize the post-rift
tectonic. The specific objectives are: to characterize the Neogene and Quaternary
sedimentary units that outcrop of the Potiguar Basin; to show how the NW-SEtrending
Afonso Bezerra Faults System deformed outcrop rocks in the Basin; to
describe soft-sediment deformation in gravels of the Quaternary Alluvial Deposits
from A?u River. Facies analyses, grain-size studies, luminescence dating, remote
sensing, structural mapping, shallow geophysics (georadar), paleostress and
petrography were carried out. The structural mapping and the georadar sections
indicated that the Carnaubais and Afonso Bezerra fault systems formed fractures,
silicified and non-silicified faults or deformation bands, affecting mainly the A?u,
Janda?ra and Barreiras formations. The petrographic data indicate that the strong
silicification resulted in a sealant character of the faults. Paleostress analysis
indicates that two stress fields affected the Basin: the first presented N-S-trending
compression, occurred from the Neocretaceous to the Miocene; the second stress
field presents E-W-trending compression, acts from the Miocene to the present. It
was verified once the Afonso Bezerra System Faults was reactivated in periods
post-Campanian and affects all post-rift lithostratigraphic units of Potiguar Basin,
including Quaternary sedimentary covers. The study about soft-sediment
deformation structures indicates that they are similar in morphology and size to
modern examples of seismically-induced deformation strutures in coarse sediments.
TL and OSL ages indicate that sediment deposition and associated soft-sediment
deformation occurred at least six times from ~352 Ka to ~9 Ka. Finally these studies
demonstrate how recent is tectonics in the Basin Potiguar / Os estudos sobre as bacias sedimentares brasileiras se concentram em sua fase
rifte, enquanto a fase p?s-rifte tem sido considerada um per?odo de pouca
atividade. A sequ?ncia p?s-rifte da Bacia Potiguar, no extremo nordeste brasileiro,
j? foi considerada pouco deformada, contudo, in?meros trabalhos v?m
demonstrando como ela ? afetada por importantes sistemas de falhas. A finalidade
geral desta tese ? caracterizar a tect?nica p?s-rifte na Bacia Potiguar. Os objetivos
espec?ficos s?o: caracterizar as unidades sedimentares cenozoicas aflorantes e a
tect?nica associada; evidenciar como o Sistema de Falhas de Afonso Bezerra
deformou rochas aflorantes da Bacia; descrever deforma??o em sedimentos
inconsolidados nos conglomerados dos Dep?sitos Aluviais quatern?rios do Rio
A?u. An?lises de f?cies, estudos granulom?tricos, data??o por luminesc?ncia,
sensoriamento remoto, mapeamento estrutural, geof?sica rasa (georadar), an?lises
de paleotens?es e petrografia foram realizados. O mapeamento estrutural e as
sec??es de georadar indicaram que os sistemas de falhas Carnaubais e Afonso
Bezerra formaram juntas, falhas silicificadas e n?o-silicificadas e bandas de
deforma??o, afetando principalmente as forma??es A?u, Janda?ra e Barreiras. Os
dados petrogr?ficos indicam que a forte silicifica??o deu ?s falhas um car?ter
selante. O estudo de paleotens?es indica dois campos de tens?es afetando a
Bacia: o primeiro, com compress?o N-S, atuou do Neocret?ceo ao Mioceno; o
segundo, com compress?o E-W, atua do Mioceno ao presente. Constatou-se que o
Sistema de Falhas de Afonso Bezerra foi reativado em per?odos p?s-campanianos
e afeta todas as unidades litoestratigr?ficas p?s-rifte da Bacia Potiguar, inclusive as
coberturas quatern?rias. O estudo sobre deforma??o em sedimentos
inconsolidados indica que esta ? similar na morfologia e no tamanho aos exemplos
modernos de estruturas de deforma??o sismicamente induzida em sedimentos
grossos. Idades por TL e LOE indicam que a deposi??o dos sedimentos e a
deforma??o associada ocorreram pelo menos em seis eventos entre
aproximadamente 352 Ka e 9 Ka. Enfim estes estudos demonstram qu?o recente ?
a tect?nica na Bacia Potiguar
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/18359 |
| Date | 08 February 2011 |
| Creators | Lima, Elissandra Nascimento de Moura |
| Contributors | CPF:37923579415, http://lattes.cnpq.br/6050302316049061, Rossetti, Dilce de F?tima, CPF:51934183920, http://lattes.cnpq.br/0307721738107549, Morales, Norberto, CPF:01720633886, http://lattes.cnpq.br/5136594572347865, Xavier Neto, Pedro, CPF:16361121372, Bezerra, Francisco Hilario Rego |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Geodin?mica e Geof?sica, UFRN, BR, Geodin?mica; Geof?sica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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