Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-06-02T21:22:09Z No. of bitstreams: 1 LuziaLinianeDoNascimentoSilva_DISSERT.pdf: 11385354 bytes, checksum: 2d90e69f54674eb5848d7ade3b31a1f4 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-06-06T23:17:12Z (GMT) No. of bitstreams: 1 LuziaLinianeDoNascimentoSilva_DISSERT.pdf: 11385354 bytes, checksum: 2d90e69f54674eb5848d7ade3b31a1f4 (MD5) / Made available in DSpace on 2017-06-06T23:17:12Z (GMT). No. of bitstreams: 1 LuziaLinianeDoNascimentoSilva_DISSERT.pdf: 11385354 bytes, checksum: 2d90e69f54674eb5848d7ade3b31a1f4 (MD5) Previous issue date: 2017-02-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A plataforma continental externa, setentrional do Rio Grande do Norte ? uma zona de transi??o fisiogr?fica, sedimentol?gica e de processos oceanogr?ficos marcada pelas varia??es eust?ticas do Quatern?rio. Neste estudo, n?s investigamos os ambientes recifais para entender a evolu??o geodin?mica da plataforma externa. Para tanto, o sonar de varredura lateral foi utilizado para mapear uma ?rea de 500 km?, entre os munic?pios de Macau e S?o Bento do Norte, paralelamente ? quebra da plataforma, al?m de 74 amostras sedimentares e da integra??o dos dados com fotografias subaqu?ticas e batimetria j? existentes para ?rea, a fim de validar as interpreta??es sonogr?ficas. Os principais objetivos deste trabalho s?o compreender como a geomorfologia antecedente da plataforma pode afetar o desenvolvimento dos recifes, e como os recifes se estabeleceram durante as varia??es holoc?ncias do n?vel do mar. Como resultados, foram identificados 7 padr?es de retroespalhamento (P1 a P7) associados a 11 f?ceis sedimentares (f?ceis biocl?sticas e silicicl?sticas), recifes distribu?dos em mont?culos, por vezes, orientados na dire??o NW-SE, e o paleovale do rio A?u. A f?cies areia biocl?stica com gr?nulos ? predominante, estando relacionada ao padr?o de retroespalhamento P6. Esta f?ceis ? respons?vel pela elevada porcentagem dos teores de mat?ria org?nica e carbonato da ?rea. Os recifes mapeados est?o situados em ?guas de 35 m de profundidade, e apresentam extens?o de dezenas a quil?metros de metros. ? poss?vel ver o alinhamento desses recifes em algumas regi?es, o que pode ser ind?cio de substratos antecedentes de antigas linhas de costa. Al?m disso, a fisiografia da plataforma em batentes e terra?os, a pouca sedimenta??o e as r?pidas varia??es do n?vel do mar no Holoceno controlaram a evolu??o dos recifes. / The outer continental shelf, northern Rio Grande do Norte is a zone of physiographic transition, sedimentological and oceanographic processes marked by eustatic variations of the Quaternary. In this study, we investigated the reef environments to understand the geodynamic evolution of the outer shelf. Therefore, the side scan sonar was used to map an area of 500 km?, between the municipalities of Macau and S?o Bento do Norte, in parallel with the shelf break, in addition to 74 sedimentary samples and and the integration of the data with underwater photographs and bathymetry already existent to the area, in order to validate the sonographic interpretations.The main aims of this study are to understand how the antecedent geomorphology of the shelf can affect the development of the reefs, and how the reefs settled during the sea level Holocene variations. As a result, 7 backscatter patterns (P1 to P7) were associated with 11 sedimentary faceis (bioclastic and siliciclastic faceis), reefs distributed in mounds, sometimes oriented in the NW-SE direction, and the paleovalley of the A?u river. The bioclastic sand facies with granules is predominant, being related to the backscatter pattern P6. This sedimentary faceis is responsible for the high percentage of the organic matter and carbonate contents of the area. The reefs mapped are located in waters of 35 m depth, and themselves extend from tens to kilometers of meters. It is possible to see the alignment of these reefs, mainly in the western region, which may be indicative of antecedent substrates of old coastlines. In addition, the physiography of the shelf on steps and terraces, low sedimentation and rapid variations in sea level in the Holocene controlled the evolution of reefs.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-25T19:35:28Z No. of bitstreams: 1 ClaudeteRodriguesDeSouza_DISSERT.pdf: 7248197 bytes, checksum: 517f3832b2c0793432a194051a3ea304 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-28T22:35:34Z (GMT) No. of bitstreams: 1 ClaudeteRodriguesDeSouza_DISSERT.pdf: 7248197 bytes, checksum: 517f3832b2c0793432a194051a3ea304 (MD5) / Made available in DSpace on 2016-07-28T22:35:34Z (GMT). No. of bitstreams: 1 ClaudeteRodriguesDeSouza_DISSERT.pdf: 7248197 bytes, checksum: 517f3832b2c0793432a194051a3ea304 (MD5) Previous issue date: 2014-04-03 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Este estudo foi desenvolvido em uma ?rea localizada na plataforma externa da Bacia Potiguar, margem equatorial brasileira. A amostragem de sedimentos foi realizada em tr?s campanhas, em torno de um po?o explorat?rio, para comparar as propriedades dos sedimentos do fundo marinho, incluindo granulometria, composi??o, conte?do de carbonato e mat?ria org?nica, anterior a perfura??o do po?o, com amostras coletadas 3 e 12 meses ap?s a perfura??o. O planejamento amostral utilizou 16 esta??es localizadas em 4 radiais distantes 50 m, 100 m, 250 m e 500 m do po?o. Os sedimentos foram analisados nas camadas 0-2 cm e 0-10 cm. Os resultados mostraram que a cobertura sedimentar em torno do po?o era pobre a muito pobremente selecionada, com granulometria predominante na fra??o areia grossa com granulo e cascalho, seguida por cascalho e lama. O conte?do de carbonato de c?lcio foi maior que 96%, associado a sedimentos biocl?ticos, e o conte?do de mat?ria org?nica foi menor que 12%. Apenas pequenas varia??es sedimentol?gicas ocorreram na ?rea afetada pelas opera??es de perfura??o. A principal diferen?a foi observada em amostras da segunda campanha, em termos de uma mudan?a na distribui??o granulom?trica associada a um aumento no conte?do de sedimentos silicicl?sticos. Este impacto ocorreu nos sedimentos mais superficias (0-2 cm), no raio mais pr?ximo ao po?o (50 m), e poderia sugerir o efeito da perfura??o. Entretanto, os sedimentos coletados na campanha 3, um ano ap?s a perfura??o, voltaram a apresentar as mesmas caracter?sticas da primeira campanha. Estes resultados indicam que n?o houve varia??es sedimentol?gicas significantes devido a atividade de perfura??o, e que a din?mica oce?nica na ?rea de estudo foi forte o suficiente para recuperar as caracter?sticas originais do ambiente. ABSTRACT This study was developed in an area located on the outer shelf in the Potiguar Basin, Brazilian equatorial margin; this tropical shelf represents a modern, highly dynamic mixed carbonate-siliciclastic system. Field sampling was carried out during 3 cruises surrounding a shallow-water exploratory well to compare sediment properties of the seafloor, including grain-size, texture, mineral composition, carbonate content, and organic matter, prior to drilling with samples obtained 3 and 12 months after drilling. The sample grid used had 16 stations located along 4 radials from 50 m the well up to a distance of 500 m. Sediments were analyzed in the first 0-2 cm, and 0-10 cm layers. The results show that sedimentary cover around the well is poor to very poorly sorted, with the particle size predominantly in the medium to coarse sand fraction, followed by gravel and mud. The content of calcium carbonate is greater than 96%, associated to bioclastic sediments, and the content of organic matter is less than 12%. Only minor sedimentological variations occured ?in the area affected by drilling operations. The most noticeable effects were observed during the second cruise, in terms of a change in grain size distribution associated to an increase in siliciclastic content, This impact occurred in the most surficial sediment (0-2 cm), in the radial closest to the well (50 m), and could suggest the effects of drilling. However, in the third cruise, one year after drilling, the sediments return to show the same characteristics as in the first cruise. These results show no significant sedimentological variations due to drilling activity, and indicate that ocean dynamics in this area was high enough to recover the environment original characteristics. / This study was developed in an area located on the outer shelf in the Potiguar Basin, Brazilian equatorial margin; this tropical shelf represents a modern, highly dynamic mixed carbonate-siliciclastic system. Field sampling was carried out during 3 cruises surrounding a shallow-water exploratory well to compare sediment properties of the seafloor, including grainsize, texture, mineral composition, carbonate content, and organic matter. Cruise 1 (C1) was carried prior to drilling, while Cruise 2(C2) and 3 (C3) respectivelly 3 and 12 months after drilling. The sample grid used had 16 stations located along 4 radials from 50 m the well up to a distance of 500 m. Sediments were analyzed in the first 0-2 cm, and 0-10 cm layers. The results show that sedimentary cover around the well is poor to very poorly sorted, with the particle size predominantly in the medium to coarse sand fraction, followed by gravel and mud. The content of calcium carbonate is greater than 96%, associated to bioclastic sediments, and the content of organic matter is less than 12%. Only minor sedimentological variations occured in the area affected by drilling operations. Mainly observed during the second cruise, in terms of a change in grain size distribution associated to an increase in siliciclastic content, This impact occurred in the most surficial sediment (0-2 cm), in the radial closest to the well (50 m), and could suggest the effects of drilling. However, in the third cruise, one year after drilling, the sediments return to show the same characteristics as in the first cruise. These results show no significant sedimentological variations due to drilling activity, and indicate that ocean dynamics in this area was high enough to recover the environment original characteristics.