Made available in DSpace on 2015-03-13T17:08:40Z (GMT). No. of bitstreams: 1 VeronicaDA.pdf: 5709097 bytes, checksum: 4074580aee5ec2b7d354ddab1d446e43 (MD5) Previous issue date: 2006-05-19 / This work presents geophysical and geological results obtained in a dunefield located in the east coast of Rio Grande do Norte State, with the aim to recognize the aeolian body depositional geometries to a future geologic modeling of the aeolian petroliferous reservoirs. The research, which was done in blowouts region situated at Nisia Floresta Municipally, included the characterization of external geometries with GPS and internal geometry analysis by GPR. Data was integrated in GoCAD software, where it was possible the three-dimensional characterization and interpretation of the studied deposits. The interpretation of GPR profiling allowed identifying: First-order bounding surfaces that separated the aeolian deposits of the Barreiras Formation rocks; Second-order bounding surfaces, which limit dune generations and Third-order bounding surfaces, a reactivation surface. This classification was based and adapted by the Brookfield (1977) and Kocurek (1996) propose. Four radarfacies was recognized: Radarfacies 1, progradational reflectors correlated to foresets of the dunes, Radarfacies 2, plain parallels reflectors related to sand sheets, Radarfacies 3, plain parallels reflectors associated to reworking of the blowout dune crest and Radarfacies 4, mounded reflectors associated to vegetated mound of sand or objects buried in subsurface. The GPR and GPS methods was also employed to the monitoring of dunefields susceptible to human activities in Buzios Beach, where the constructions along the blowout region and the tourism are changing the natural evolution of the deposits. This fact possibly to cause negative impacts to the coastal zone. Data obtained in Dunas Park, a unit environmental conservation, was compared with information of the Buzios Beach. There is a major tendency of erosion in Buzios, specifically in blowout corridor and blowout dune / Este trabalho apresenta os resultados geol?gicos e geof?sicos obtidos em um campo de dunas situados no litoral oriental do Rio Grande do Norte e teve como objetivo definir as geometrias deposicionais dos corpos e?licos para posterior aplica??o na modelagem geol?gica de campos produtores de ?leo e g?s de origem e?lica. A pesquisa foi realizada em uma regi?o de blowouts, situada no munic?pio de N?sia Floresta - RN, onde foi poss?vel definir a superf?cie externa com o uso do GPS geod?sico e a estrutura??o interna utilizando o GPR (Ground Penetrating Radar). Estes dados foram integrados no software de modelagem geol?gica Gocad, permitindo a visualiza??o tridimensional e interpreta??o dos dep?sitos estudados. O levantamento de perfis geof?sicos permitiu a investiga??o da geometria interna dos dep?sitos, nos quais foi poss?vel reconhecer superf?cies limitantes de 1? ordem (superf?cie deposicional que separa os dep?sitos e?licos de rochas da Forma??o Barreiras), 2? ordem (superf?cie que separa diferentes pulsos de sedimenta??o e?lica) e 3? ordem (superf?cies de reativa??o). A classifica??o destas superf?cies acima descritas foi baseada e modificada das propostas de Brookfield (1977) e Kocurek (1996). Foram ainda definidas quatro radarf?cies, com base na forma e termina??o dos refletores: Radarf?cies 1, representada por refletores progradantes, os quais se relacionam aos foresets das acumula??es e?licas; Radarf?cies 2, que ? constitu?da por refletores suscept?veis ? a??o antr?pica na praia de B?zios, onde constru??es ao longo da regi?o de blowouts e a pr?tica intensiva de turismo est?o modificando o desenvolvimento natural destas acumula??es e?licas, podendo gerar impactos ambientais negativos para a zona costeira. Dados obtidos numa ?rea situada no Parque das Dunas (unidade de conserva??o ambiental) foram utilizados para compara??o com as informa??es adquiridas em B?zios. H? uma tend?ncia maior de eros?o na ?rea de B?zios, notadamente no corredor do blowout e na duna de blowout

L’évolution des systèmes sédimentaires jurassiques (Pliensbachien-Bajocien) dans le secteur de Zaouiat-Ahançal (Haut Atlas, Maroc) est localement influencée par des mouvements diapiriques associés à la ride du Jbel Azourki. Cette structure tectonique complexe suit un tracé en baïonnette d’orientation globale OSO-ENE sur près de 60 kilomètres, ponctué par six affleurements de matériel diapirique triasique. L’objectif de cette thèse est de caractériser l’impact du diapirisme sur la géométrie des dépôts et sur la distribution des faciès au sein de trois systèmes de dépôt successifs : (1) un système carbonaté de plate-forme peu profonde (Formations d’Aganane, de Jbel Choucht et d’Assemsouk) (2) des systèmes de rampe mixte silicoclastique et carbonatée (Formations de Tamadout, d’Amezraï, de Tafraout et d’Aguerd-n-Tazoult), (3) et un système carbonaté oolitique (Formation de Bin-El-Ouidane). Une cartographie détaillée des unités stratigraphiques et des unités de faciès, ainsi qu’une série de quatorze coupes géologiques de la ride diapirique du Jbel Azourki ont ainsi été réalisées. L’étude des interactions entre sédimentation et diapirisme révèle un enregistrement continu de la déformation diapirique sur l’ensemble de la série sédimentaire, et a permis d’établir une chronologie de l’activité diapirique dans le secteur de Zaouiat-Ahançal. L’unité des calcaires inférieurs (1) enregistre une déformation polyphasée marquée par le développement localisé, au sein de la plate-forme, de bassins d’extension kilométrique caractérisés par une sédimentation hémipélagique et gravitaire (rim basins). Ces bassins circonscrits aux diapirs sont limités par des bordures de plate-forme bioconstruites à Lithiotis, de type aggradant ou érosif. À partir du Pliensbachien terminal, les déformations syndiapiriques se manifestent dans les unités mixtes (2), d’une part à l’échelle plurikilométrique avec l’accumulation de plusieurs milliers de mètres de dépôts, contrôlée par la variation latérale du taux de subsidence entre et au sein des compartiments nord et sud de la ride, et d’autre part à l’échelle hectométrique de la bordure du diapir avec des géométries caractéristiques et des variations de faciès (micro plates-formes à oolites et coraux). La ride diapirique perce en surface pendant le dépôt des unités mixtes, puis est recouverte par l’unité transgressive peu déformée des calcaires supérieurs (3) à l’Aalénien terminal. Les paramètres de contrôle de la géométrie des dépôts et de la distribution des faciès autour de la ride diapirique du Jbel Azourki correspondent aux variations locales de subsidence liées aux mouvements de la couche de sel en profondeur, au taux de sédimentation et à leur rapport relatif. Ils s’inscrivent dans un contexte tectonique régional, et climatique global, qui définit l’accommodation générale et le type de remplissage sédimentaire du bassin atlasique. Le type de sédimentation, carbonatée ou mixte, joue un rôle prépondérant dans ces manifestations tectono-sédimentaires. / The evolution of the Jurassic sedimentary systems (Pliensbachian-Bajocian) in Zaouiat-Ahançal area (High Atlas, Morocco) is locally controlled by diapiric movements related to the Jbel Azourki ridge. This nearly-60-kilometer-long complex tectonic structure follows an overall WSW-ENE “bayonet-shape” outline, punctuated by six Triassic diapiric outcrops. The aim of this thesis is to characterize the role of diapirism on depositional geometries and facies distribution in three successive sedimentary systems: (1) a shallow-carbonate platform system, (2) mixed siliciclastic- and carbonate-ramp systems and (3) an oolitic-carbonate system. Therefore, a detailed geological map with the stratigraphic and facies units has been realized, as well as a set of fourteen geological sections across the Jbel Azourki diapiric ridge. The analysis of the interactions between sedimentation and diapirism has revealed a continuous recording of diapiric deformation by the entire sedimentary succession, allowing the establishment of a chronology of diapiric activity in the Zaouiat-Ahançal area. The lower-carbonate unit (1) records a polyphase deformation with the development of localized kilometer-scale basins within the platform, characterized by hemipelagic and gravity-flow deposits (rim basins). These basins are confined around the diapirs and bounded by Lithiotis-bioconstructed platform margins, which can be aggradational or erosional. From the late Pliensbachian, the mixed units (2) were affected firstly by syn-diapiric deformations at a pluri-kilometer scale, with the accumulation of several thousand-meter-thick deposits, controlled by lateral variations of the subsidence rate in and between the northern and southern flanks of the ridge, and secondly by syn-diapiric deformations at a hectometer- “diapir-edge” scale, with characteristic geometries and facies variations (oolite- and coral-rich micro platforms). The diapiric ridge reached the surface during the deposition of the mixed units and was finally capped by slightly deformed transgressive upper-carbonate unit (3) in the late Aalenian. The controlling factors on depositional geometries and facies distribution around the Jbel Azourki diapiric ridge are the local variations of the subsidence rate related to salt-movement, the sedimentation rate, and their relative ratio. They are part of the regional tectonic and global climate settings which defined the overall accommodation rate and the sedimentary filling of the atlasic basin. The type of sedimentation, carbonate- or mixed-dominated, played a major role in these tectonic-sedimentary responses.