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Previous issue date: 2016-08-05 / Essa disserta??o apresenta um estudo geof?sico de uma intrus?o b?sica
cenozoica, envolvendo etapas de aquisi??o, processamento e modelagens 2D e 3D de
dados magn?ticos e gravim?tricos terrestres. O alvo estudado ? um plug conhecido
como S?o Jo?o, intrusivo em rochas sedimentares da borda sul da Bacia Potiguar, regi?o
setentrional do Rio Grande do Norte. Com uma ?rea aproximada de 0,5 km?, este plug ?
um dos diversos corpos ?gneos constituintes do Magmatismo Macau (50-7 Ma). Os
arenitos e calc?rios pr?ximos ao corpo subvulc?nico sofreram modifica??es
mineral?gicas significativas por efeito termal. Utilizamos dados magn?ticos
aerolevantados do Projeto Bacia Potiguar e aquisi??es terrestres, que resultaram em
5698 leituras com o magnet?metro de campo total e 128 esta??es gravim?tricas com o
grav?metro CG5. O mapa das derivadas verticais do campo magn?tico an?malo dos
dados a?reos contextualizou regionalmente a geologia e geof?sica da Bacia Potiguar,
enquanto que os dados magn?ticos e gravim?tricos terrestres detalharam o plug S?o
Jo?o e foram utilizados para as modelagens. Foram realizadas medidas de
susceptibilidade magn?tica e densidade em amostras de rochas metam?rficas (buchitos),
?gneas (diab?sio) e sedimentares (arenito e calc?rio). Tais medidas auxiliaram na
constru??o de modelos 2D e 3D, revelando a arquitetura interna do plug S?o Jo?o, cujas
profundidades chegam a cerca de 400 m. O modelo gravim?trico apresenta uma
geometria no formato de lop?lito, com uma regi?o na parte nordeste do corpo
apresentando maiores contrastes de densidade. Tal regi?o ? tamb?m observada no
modelo magn?tico, com altos contrastes de susceptibilidade magn?tica. M?ximos
gravim?tricos pr?ximos ao plug indicam tr?s regi?es com contrastes de densidade
positivos, que podem ser corpos ?gneos sem express?o em superf?cie. / This dissertation presents a geophysical study of a Cenozoic basic intrusion,
involving steps of acquisition, processing, and 2D and 3D modeling of terrestrial
magnetic and gravity data. The target studied is a plug known as S?o Jo?o, located in
the southern border of the Potiguar Basin (NE Brazil). This plug has an area of
approximately 0.5 km? and was formed by magmatism Macau. Sandstones and
limestones near the hipoabissal body suffered metamorphization with significant
thermal changes. We use airborne magnetic data named Potiguar Basin Project and
terrestrial acquisition, which resulted in 5698 readings with the total field magnetometer
and 128 gravity stations with CG5 gravimeter. The map of vertical derivative of the
total magnetic intensity anomalies from the airborne data contextualized regionally the
geology and geophysics of the Potiguar Basin, while the terrestrial magnetic and
gravimetric data detailed the plug S?o Jo?o and were used for the modeling. Magnetic
susceptibility and density were measured in metamorphic (buchites) igneous (diabase)
and sedimentary (sandstone and limestone) rock samples. Such measures help to
constrain the 2D and 3D modeling, which reveal the internal architecture of the S?o
Jo?o plug, whose maximum depths reach 400 m. The gravity model of the plug shows a
lopolith shape, with a region in the northeastern part of the body having higher density
contrast. This region is also observed in the magnetic model with high contrast of
magnetic susceptibility. Gravity highs closer to S?o Jo?o plug indicate three regions
with high density contrasts, which probably are igneous bodies with no surface
expression.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21698 |
| Date | 05 August 2016 |
| Creators | Damaceno, Juliana Garrido |
| Contributors | 40623742420, Souza, Zorano S?rgio de, 15603180404, Ferreira, Francisco Jos? Fonseca, 03739538449, Castro, David Lopes de |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM GEODIN?MICA E GEOF?SICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| 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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