Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / It was carried out an identification of dry events and elaborated a dynamic and thermodynamic characterization of these ones, ocurring during summer over Southeast region of Brazil. Dry events were identified for a series of 35 years of daily interpolated precipitation data set. As the Southeast region has a wide territory, it presents different precipitation regimes, both spacially and temporally, and for this reason, it was divided into three subregions with homogeneous precipitation regimes through cluster analysis. This division has sectorized the Southeast region approximately in a meridional form, with the southernmost portion denominated R1, central portion R2 and the northernmost R3. It was evaluated two different temporal scales of dry events: synoptic (duration between 5 and 9 days) and intraseasonal (duration equal or greater than 10 days) for the R1, R2 and R3 regions separately. R3 presented the highest total number of dry events in both categories (synoptic and intraseasonal), followed by R2 and R1 respectively. It was computed composites, with reanalysis data for different meteorological variables, associated with synoptic and intraseasonal dry events for each of the three homogeneous precipitation regions. Concerning mean dynamic patterns associated with dry events, there were two main ones that drew the most attention. For synoptic dry events in R1, there was a predominance of a blocking ridge at various levels of the atmosphere over the entire southern portion of South America, diverting the transient systems towards the more central portions of the Atlantic Ocean. While for the rest of the dry (synoptic and intraseasonal) classes of events and for the different homogeneous regions of precipitation (R1, R2 and R3), dry events appeared to be more associated with a blocking high centered on the South and Southeast regions of Brazil. Some other characteristics found were: in all classes of dry events, it was noticed in the average outgoing longwave radiation (OLR) fields, a precipitation dipole indicative between the concerned region and the Plata Basin (Uruguay, northern Argentina, southern Paraguay and southern Brazil). For intraseasonal dry events over R1 and R2, positive rainfall anomalies were also detected over a wide area of Amazon, whereas in the R1 synoptic dry events was noticed the presence of rainfall over Northeast region of Brazil. The increase in precipitation over the Plata basin was generally associated with the intensification of the South America low-level jet east of the Andes, caused by the intrusion of a low-level anticyclonic anomaly between the coasts of the South and Southeast regions of Brazil, providing anomalous easterly winds over the Southeast and anomalous westerly winds over the Plata basin. For all dry events, except for the synoptic events in R1, at high levels of the troposphere, an anticyclonic anomaly was observed on the South of Brazil, in the same way providing anomalous easterly winds on the Southeast, whereas over Plata mouth (border between Uruguay and Argentina), anomalous westerly winds were observed, on a region that climatologically occurs the Upper Tropospheric Jet Streams, which was intensified by the anomalous westerly winds, contributing to the convection that are typically observed in the equatorial Upper Tropospheric Jet entrance. The increase in the convective activity over the Plata basin and its absence over the Southeast region of Brazil, led to an anomalous displacement to the south of the meteorological systems that are characteristical in high levels of the troposphere during the South American summer, such as the Bolivian High and the high level cyclonic vortex of the Northeast of Brazil. The composites associated with the intraseasonal dry events occurring during the 2013/14 and 2014/15 summer, when there was a large repercussion of the rainfall scarcity on the Southeast region, were similar to those described above, but the anomalies in practically all the dynamic and thermodynamic fields were more prominent. / Foi realizada a identificação de eventos secos e elaborada uma caracterização dinâmica e termodinâmica média destes durante a estação de verão sobre a região Sudeste do Brasil. Foram identificados eventos secos para uma série de 35 anos de dados de precipitação diária interpolada em pontos de grade. Como a região Sudeste possui um território muito amplo, apresenta diferentes regimes de precipitação, tanto espacial quanto temporalmente, e por esta razão, foi dividida em três sub-regiões com regimes homogêneos de precipitação por meio da análise de cluster. Essa divisão setorizou a região Sudeste aproximadamente de forma meridional, com a porção mais ao sul sendo denominada R1, mais central R2 e a mais setentrional R3. Foram avaliados eventos secos com duas diferentes escalas temporais: sinótica (duração entre 5 e 9 dias) e intrasazonal (duração igual ou superior a 10 dias) para as regiões R1, R2 e R3 separadamente. A região R3 foi a que apresentou o maior número total de eventos secos em ambas categorias (sinótico e intrasazonal), seguida por R2 e R1 respectivamente. Foram computados campos médios com dados de reanálise, de diversas variáveis meteorológicas, associados aos eventos secos sinóticos e intrasazonais para cada uma das três regiões homogêneas de precipitação. Quanto aos padrões dinâmicos médios associados aos eventos secos, houve dois principais a chamarem mais a atenção. Para eventos secos sinóticos em R1, exisitiu a predominância de uma crista de bloqueio em vários níveis da atmosfera sobre toda a porção sul da América do Sul, desviando os sistemas transientes em direção as porções mais centrais do Oceano Atlântico. Enquanto que para o restante das classes de eventos secos (sinóticos e intrasazonais) e para as diferentes regiões homogêneas de precipitação (R1, R2 e R3), os eventos pareceram estar mais associados a uma alta de bloqueio centrada sobre a região litorânea das regiões Sul e Sudeste do Brasil. Algumas outras características encontradas foram: em todas as classes de eventos secos, notou-se nos campos médios de radiação de onda longa emitida (ROLE) um indicativo de dipolo de precipitação entre a região em questão e a bacia do Prata (Uruguai, norte da Argentina, sul do Paraguai e sul do Brasil). Para eventos secos intrasazonais em R1 e R2 também detectou-se superávits de precipitação sobre uma ampla área da Amazônia, enquanto que para eventos secos sinóticos em R1 houve a presença de chuvas sobre o Nordeste do Brasil. O aumento da precipitação sobre a bacia do Prata em geral esteve associado a intensificação do Jato de Baixos Níveis da América do Sul (JBNAS) junto a cordilheira dos Andes, causada pela intrusão de uma anomalia anticiclônica em baixos níveis entre as costas das regiões Sul e Sudeste do Brasil, propiciando ventos anômalos de leste sobre o Sudeste e ventos anômalos de oeste sobre a bacia do Prata. Para todos os eventos secos, com exceção dos eventos sinóticos em R1, notou-se em altos níveis da troposfera uma anomalia anticiclônica sobre o Sul do Brasil, propiciando ventos anômalos de leste sobre a região Sudeste, enquanto que sobre a foz do Prata (divisa entre Uruguai e Argentina) observou-se ventos anômalos de oeste, sobre uma região que climatologicamente ocorrem os Jatos de Altos Níveis (JAN), os quais foram intensificados pelos ventos anômalos de oeste sobre esta latitude, contribuindo para os movimentos verticais que tipicamente são observados na entrada equatorial do JAN. O aumento da atividade convectiva sobre a bacia do Prata e a ausência dela sobre a região Sudeste do Brasil propiciou um deslocamento anômalo para sul dos sistemas meteorológicos que são característicos em altos níveis da troposfera durante o verão da América do Sul, como a Alta da Bolívia (AB) e o VCAN do Nordeste. O caráter dos campos médios associados aos eventos secos intrasazonais ocorridos durante os verões de 2013/14 e 2014/15, anos em que houve uma grande repercussão da escassez das chuvas sobre o Sudeste, se mostraram similares as descritas acima, porém as anomalias em praticamente todos os campos dinâmicos e termodinâmicos se mostraram mais proeminentes.

Made available in DSpace on 2015-02-24T19:48:36Z (GMT). No. of bitstreams: 1 MariaGL_Pag1_a_ pag155.pdf: 5724058 bytes, checksum: a4a3f020e03eb5871536940d36dc3b18 (MD5) Previous issue date: 2008-07-25 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Until some years ago, weathering geochronology was primarily based on the K-Ar and 40Ar/39Ar dating of supergene minerals. Recent advances in the analysis of supergene goethite by the (U-Th)/He method expanded the number of suitable minerals for such purpose, as well as the time of application for weathering geochronology. This study represents the first systematic approach in Brazil, combining both the 40Ar/39Ar e (U-Th)/He methodologies to improve the knowledge on the weathering and the age of nonfossiliferous sediments. Supported by geologic and geomorphologic correlations, we identified different types of weathering profiles occurring in the interior and coastal areas of northeastern Brazil. These profiles were correlated to main regional geomorphological domains: the Borborema Plateau , the Sertaneja Depression , and the Coastal Cuestas and Plains, and respective planation surfaces, which study is fundamental to understand the landscape evolution of the northern portion of the eastern Borborema Province. The depth and stratigraphic organization of the weathering profiles in each of the geomorphological domains permitted to establish that: (i) the profiles on the highlands that cap the Borborema Surface are deeper (up to 100 m) and can be considered as typical lateritic profiles; (ii) on the lowlands that form the Sertaneja Surface , the weathering profiles are shallow and poorly developed (2-5 m deep); (iii) the profiles along the coastal area are moderately developed (up to 25 m deep), and are characterized by thick saprolites and mottle zones. Aiming to establish the timing of the evolution of northeastern Brazil, we studied 29 weathering profiles representing distinct topographic levels of the Borborema Province, from the highlands to the coast, through the analysis of 248 grains of supergene manganese oxides using laser step-heating 40Ar/39Ar geochronology. Additionally, we applied the (U-Th)/He method in 20 weathering profiles, by dating 171 grains of supergene iron oxides and hydroxides. Geochronological results for 248 grains of manganese oxides analyzed by the 40Ar/39Ar method indicate that the weathering profiles in the study area record the history of weathering from the Oligocene to the Pleistocene, with ages in the order of 31.4 ? 1.0 Ma to 0.8 ? 0.4 Ma. Dating of 171 grains of goethite by the (U-Th)/He method yielded ages ranging from 43.2 ? 4.3 Ma to 0.8 ? 0.1 Ma, suggesting the weathering processes last from the Eocene to the Pleistocene. The precipitation of supergene goethite in this interval confirms the age of the weathering processes identified from the manganese oxides record. 105 goethite grains from 8 different occurrences of the Barreiras Formation were dated by the (U-Th)/He method. Five grains collected from the cement in the Barreiras Formation sandstones, in the Lagoa Salgada and Rio do Fogo coastal cuestas, yielded ages of 17.6 ? 1.8 Ma, 17.3 ? 1.7 Ma, 16.3 ? 1.6 Ma, 16.2 ? 1.6 Ma and 13.6 ? 1.4 Ma. Results of 69 goethite grains from authigenic pisoliths collected in 7 different localities also yielded concordant ages, varying from 17.8 ? 1.8 to 7.5 ? 0.8 Ma. Results obtained from 31 detrital grains are concordant in 3 distinct localities (Lagoa Salgada, Praia da Gar?as e Ponta Grossa); they vary in the range of 43.2 ? 4.3 to 21.6 ? 2.2 Ma, and indicate that the maximum age for the Barreiras Formation deposition is around 22 Ma. 40Ar/39Ar results for 15 manganese oxides grains associated with the Barreiras Formation weathering profiles, in 3 different localities, vary from 13.1 ? 0.9 to 7.7 ? 0.4 Ma, in the same range of ages obtained by the (U-Th)/He method. The systematic application of the 40Ar/39Ar and (U-Th)/He methods, respectively for manganese oxides and goethites, show that the Barreiras Formation sediments were already deposited since ca. 17 Ma, and that the weathering processes were active until ca. 7 Ma ago. The ages obtained from manganese oxides collected in the Cenozoic basalts (Macau Formation) also reveal a weathering history between 19 and 7 Ma, pointing to hot and humid conditions during most of the Miocene. 40Ar/39Ar ages yielded by manganese oxides associated with the Serra do Martins Formation vary from 14.1 ? 0.4 to 10.5 ? 0.3 Ma. On the other hand, (U-Th)/He ages from iron oxides/hydroxides collected in the Serra do Martins Formation mesas vary from 20.0 ? 2.0 to 5.5 ? 0.6 Ma, indicating that those sediments are older than 20 Ma. 40Ar/39Ar and (U-Th)/He results produced in this study are in agreement with paleoclimatic interpretations based on stable isotopes and clay index values measured in the Atlantic Ocean sediments, validating the use of weathering geochronology to investigate paleoclimatic variations. The direct dating of the Barreiras Formation permitted, for the first time, confident inferences on the age of the brittle deformation recorded by this sedimentary unit in the Rio Grande do Norte and Cear? states. The first event, syn-deposition, occurred during the early Miocene; an younger event, related to the post-depositional deformation of the Barreiras Formation, is associated with tectonic activity from the very early Miocene to the Holocene. In agreement with data from other areas, results obtained in this study reveal that the depth and complexity of the weathering profiles reflect the time of exposition of such areas to the weathering agents close to the surface. However, there is no clear relationship between ages vs. altitude. The depth and the stratigraphic organization of weathering profiles in northeastern Brazil, contrary to the southeastern Brazil pattern, do not vary toward the coast. In our study area, field observations reveal the presence of ancient, thick and complex lateritic profiles preserved in the sedimentary mesas on the Borborema Plateau, as younger, narrow and incipient ones occur in the dissected areas. Geochronological results obtained for these profiles yielded older ages on the high altitudes, and younger ages in the lowlands, suggesting the scarp retreatment is the most reliable model to explain the regional landscape evolution. However, in the coastal lowlands, the relatively older ages obtained indicate that more complexes processes were involved in the modeling of the local relief / At? recentemente, a geocronologia do intemperismo foi primeiramente baseada em data??es por K-Ar e 40Ar/39Ar de minerais superg?nicos. Recentes avan?os em an?lises por (U-Th)/He de goetitas superg?nicas expandiram o n?mero de minerais utilizados e o intervalo de tempo de aplica??o da geocronologia do intemperismo. Este trabalho representa o primeiro estudo sistem?tico, no Brasil, da combina??o das metodologias de data??o 40Ar/39Ar e (U-Th)/He, aplicadas para o conhecimento da hist?ria do intemperismo e das idades de forma??es sedimentares afossil?feras. Para entender o contexto evolutivo do relevo da por??o setentrional do Nordeste do Brasil foram identificados, com base nos estudos geol?gicos e geomorfol?gicos regionais, diferentes tipos de perfis de intemperismo que ocorrem no interior e na faixa litor?nea. Estes perfis foram correlacionados a tr?s dom?nios geomorfol?gicos distintos: o Planalto da Borborema, a Depress?o Sertaneja e as Plan?cies e Tabuleiros Costeiros, associados a superf?cies de aplainamento caracter?sticas de cada dom?nio. Baseando-se na estratigrafia e profundidade dos perfis de intemperismo desenvolvidos em cada um dos tr?s dom?nios geomorfol?gicos principais, foi poss?vel observar que: (i) os perfis que ocorrem em cotas elevadas no interior do continente, capeando a chamada Superf?cie Borborema, s?o mais profundos (podendo chegar a 100 m), sendo caracterizados como perfis later?ticos; (ii) nas ?reas de eleva??es mais baixas que constituem a Superf?cie Sertaneja ocorrem perfis mais rasos e incipientes (2-5 m de profundidade); (iii) os perfis de intemperismo que ocorrem na regi?o litor?nea s?o moderadamente desenvolvidos (podendo chegar at? 25 m de profundidade), sendo caracterizados principalmente por espessos sapr?litos e zonas mosqueadas. Visando colocar limites geocronol?gicos na evolu??o geomorfol?gica do Nordeste, 29 perfis representando desde a por??o elevada da Prov?ncia Borborema at? o litoral, foram estudados atrav?s da an?lise de 248 gr?os de ?xidos de mangan?s superg?nicos pela geocronologia de 40Ar/39Ar por aquecimento gradual a laser. Al?m disso, 20 perfis de intemperismo foram estudados atrav?s da geocronologia de (U-Th)/He, e 171 gr?os de ?xidos/hidr?xidos de ferro superg?nicos foram datados por este m?todo. Os resultados geocronol?gicos obtidos para os 248 gr?os de ?xidos de mangan?s datados pelo m?todo 40Ar/39Ar indicam que os perfis de intemperismo da ?rea estudada registram um hist?ria de intemperismo que vai desde o Oligoceno at? o Pleistoceno, apresentando idades patamar e patamar for?ado que variam de 31,4 ? 1,0 Ma a 0,8 ? 0,4 Ma. A data??o dos 171 gr?os de goetitas pelo m?todo (U-Th)/He mostraram idades variando de 43,2 ? 4,3 Ma a 0,8 ? 0,1 Ma, registrando uma hist?ria de intemperismo desde o Eoceno at? o Pleistoceno. Os registros da precipita??o de goetitas confirmam as idades dos processos de intemperismo identificados pelos registros de ?xidos de mangan?s. Data??es (U-Th)/He foram realizadas em 105 gr?os de goetitas provenientes de 8 localidades distintas da Forma??o Barreiras. Cinco gr?os provenientes do cimento dos arenitos da Forma??o Barreiras, nas localidades de Lagoa Salgada e Rio do Fogo, apresentaram idades de 17,6 ? 1,8 Ma, 17,3 ? 1,7 Ma, 16,3 ? 1,6 Ma, 16,2 ? 1,6 Ma e 13,6 ? 1,4 Ma. Os resultados obtidos para os 69 gr?os de goetitas associadas a pis?litos autig?nicos, provenientes de 7 localidades distintas, mostraram-se concordantes, apresentando valores que variam de 17,8 ? 1,8 a 7,5 ? 0,8 Ma. Os resultados obtidos para 31 gr?os de goetitas provenientes de pis?litos detr?tricos s?o compat?veis para as 3 diferentes localidades amostradas (Lagoa Salgada, Praia da Gar?as e Ponta Grossa), apresentando idades que variam de 43,2 ? 4,3 a 21,6 ? 2,2 Ma. Tais resultados indicam que a idade m?xima de deposi??o dos sedimentos da Forma??o Barreiras ? de aproximadamente 22 Ma. Os resultados 40Ar/39Ar obtidos para 15 gr?os de ?xidos de mangan?s associados ao intemperismo da Forma??o Barreiras, provenientes de 3 localidades distintas, variaram de 13,1 ? 0,9 a 7,7 ? 0,4 Ma, mostrando-se similares ?s idades das goetitas autig?nicas tamb?m coletadas nesta forma??o, por?m datadas pelo m?todo (U-Th)/He. A aplica??o sistem?tica dos m?todos 40Ar/39Ar em ?xidos de mangan?s e (U-Th)/He em goetitas mostra que os sedimentos da Forma??o Barreiras j? estavam depositados h? aproximadamente 17 Ma e que os processos de intemperismo perduraram at? pelo menos 7 Ma atr?s, indicando um per?odo de prov?vel clima quente e ?mido para a regi?o. As idades obtidas para os ?xidos de mangan?s associados aos basaltos cenoz?icos da Forma??o Macau, na localidade hom?nima, tamb?m revelam uma hist?ria de intemperismo entre aproximadamente 19 e 7 Ma, confirmando condi??es clim?ticas quentes e ?midas durante a maior parte do Mioceno. As idades 40Ar/39Ar obtidas para os ?xidos de mangan?s relacionados ? Forma??o Serra do Martins variam de 14,1 ? 0,4 a 10,5 ? 0,3 Ma. J? as idades (U-Th)/He obtidas nas amostras de ?xidos/hidr?xidos de ferro provenientes dos plat?s da Forma??o Serra do Martins variam de 20,0 ? 2,00 a 5,5 ? 0,6 Ma, sugerindo uma idade m?nima de 20 Ma para a deposi??o dos sedimentos desta forma??o. Os resultados 40Ar/39Ar e (U-Th)/He das amostras analisadas neste trabalho mostram correspond?ncia com as interpreta??es paleoclim?ticas baseadas em is?topos est?veis e ?ndices de argilas presentes nos sedimentos do Oceano Atl?ntico, confirmando a adequabilidade do uso da geocronologia do intemperismo na investiga??o paleoclim?tica de uma regi?o. Neste trabalho, a data??o da Forma??o Barreiras forneceu informa??es mais precisas sobre a idade das estruturas fr?geis que se encontram associadas ? deposi??o desta forma??o, nos estados do Rio Grande do Norte e do Cear?. O primeiro evento sin-deposicional correlacion?vel ? deposi??o da Forma??o Barreiras apresenta uma idade do Mioceno Inferior; outro evento tamb?m presente no Barreiras, por?m relacionado a um est?gio de deforma??o p?s-sedimentar apresenta uma prov?vel idade que varia do final do Mioceno Inferior ao Holoceno. Similarmente aos dados da literatura, os resultados obtidos neste trabalho revelam que a profundidade e a complexidade dos perfis de intemperismo refletem a dura??o da exposi??o destes perfis ?s condi??es intemp?ricas. Todavia, n?o foi identificada rela??o de idade vs. cota topogr?fica nos perfis estudados. A profundidade e a estratigrafia de perfis de intemperismo no Nordeste do Brasil, diferentemente do que se observa na regi?o Sudeste, n?o variam sistematicamente do interior em dire??o ? costa. Na ?rea de trabalho, observa??es de campo revelam a presen?a de perfis de intemperismo later?tico antigos, espessos e complexos, preservados nos plat?s de alta cota topogr?fica, e perfis de intemperismo recentes, rasos e incipientes nas regi?es dissecadas em volta desses plat?s. Estes resultados sugerem que o modelo de retra??o de escarpas ? o mais adequado para a explicar a evolu??o do relevo da regi?o estudada. Entretanto, nas por??es mais rebaixadas do relevo, localizadas no dom?nio das Plan?cies e Tabuleiros Costeiros, foram obtidas idades relativamente antigas, indicando que processos mais complexos atuaram no modelamento do relevo daquela ?rea

Made available in DSpace on 2015-02-24T19:48:38Z (GMT). No. of bitstreams: 1 FranciscoCCN.pdf: 4877926 bytes, checksum: c6e667c4e51b79efcbd70bc23e10536a (MD5) Previous issue date: 2008-07-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This thesis encompasses the integration of geological, geophysical, and seismological data in the east part of the Potiguar basin, northeastern Brazil. The northeastern region is located in South American passive margin, which exhibits important areas that present neotectonic activity. The definition of the chronology of events, geometry of structures generated by these events, and definition of which structures have been reactivated is a necessary task in the region. The aims of this thesis are the following: (1) to identify the geometry and kinematics of neotectonic faults in the east part of the Potiguar basin; (2) to date the tectonic events related to these structures and related them to paleoseismicity in the region; (3) to present evolutional models that could explain evolution of Neogene structures; (4) and to investigate the origin of the reactivation process, mainly the type of related structure associated with faulting. The main type of data used comprised structural field data, well and resistivity data, remote sensing imagery, chronology of sediments, morphotectonic analysis, x-ray analysis, seismological and aeromagnetic data. Paleostress analysis indicates that at least two tectonic stress fields occurred in the study area: NSoriented compression and EW-oriented extension from the late Campanian to the early Miocene and EW-oriented compression and NS-oriented extension from the early Miocene to the Holocene. These stress fields reactivated NE-SW- and NW-SE-trending faults. Both set of faults exhibit right-lateral strike-slip kinematics, associated with a minor normal component. It was possible to determine the en echelon geometry of the Samambaia fault, which is ~63 km long, 13 km deep, presents NE-SW trend and strong dip to NW. Sedimentfilled faults in granite rocks yielded Optically Stimulated Luminescence (OSL) and Single-Aliquot Regeneration (SAR) ages at 8.000 - 9.000, 11.000 - 15.000, 16.000 - 24.000, 37.000 - 45.500, 53.609 - 67.959 e 83.000 - 84.000 yr BP. The analysis of the ductile fabric in the Jo?o C?mara area indicate that the regional foliation is NE-SW-oriented (032o - 042o), which coincides with the orientation of the epicenters and Si-rich veins. The collective evidence points to reactivation of preexisting structures. Paleoseismological data suggest paleoseismic activity much higher than the one indicated by the short historical and instrumental record / Esta tese compreende a integra??o de dados geol?gicos, geof?sicos e sismol?gicos na por??o leste da Bacia Potiguar. A regi?o nordeste est? localizada na margem passiva sulamericana, exibindo importantes ?reas com registro de atividades neotect?nicas. As defini??es da cronologia dos eventos, da geometria das estruturas geradas por estes eventos e de quais estruturas foram reativadas, s?o necess?rias nesta ?rea. Os objetivos principais desta tese s?o listados a seguir: (1) identificar a geometria e cinem?tica de falhas neotect?nicas na faixa leste da Bacia Potiguar; (2) obter a idade dos eventos tect?nicos relacionados a estas estruturas e associ?-las a paleossismos na regi?o; (3) apresentar modelos evolutivos para explicar a evolu??o de estruturas ne?genas; e (4) investigar a origem dos processos de reativa??o, principalmente o tipo de fei??o geol?gica relacionada a esta reativa??o. Os principais tipos de dados usados compreendem dados de campo, po?os e dados de resistividade, imagens de sensores remotos, cronologia de sedimentos, an?lises morfotect?nica e an?lises por Difratometria de Raio X, dados sismol?gicos e aeromagn?ticos. A an?lise de paleotens?es indica que os dois ?ltimos campos de tens?es que ocorreram na ?rea de estudo form: compress?o orientada segundo a dire??o N-S e extens?o E-W, a partir do final do Campaniano ao in?cio do Mioceno, e uma compress?o orientada na dire??o E-W e extens?o N-S, a partir do Mioceno ao Holoceno. Este campo de tens?es reativou falhas de dire??o NE-SW e NW-SE. Estas falhas exibem cinem?tica transcorrente dextral, associada com uma componente normal. Neste trabalho foi poss?vel determinar a geometria en echelon da Falha Samambaia, que ? de ~63 km de extens?o, 13 km de profundidade, orientada para NE-SW, e forte mergulho para NW. As falhas preenchidas por sedimento nas rochas gran?ticas foram datadas por Luminesc?ncia Opticamente Estimulada (LOE) e Single-Aliquot Regeneration (SAR), revelando idades de: 8.000 - 9.000, 11.000 - 15.000, 16.000 - 24.000, 37.000 - 45.500, 53.609 - 67.959 e 83.000 - 84.000 anos. A an?lise do fabric d?ctil na ?rea de Jo?o C?mara indica que a folia??o regional est? orientada para NE-SW (032o - 042o Az), que coincide com a orienta??o dos epicentros e veios ricos em S?lica. O conjunto de evid?ncias aponta para a reativa??o de estruturas pr?-existentes. Os dados paleossismol?gicos sugerem atividades paleoss?smicas maiores que aquelas indicadas durante o curto per?odo de registros hist?rico e instrumental

Made available in DSpace on 2015-02-24T19:48:38Z (GMT). No. of bitstreams: 1 LilianeRC_Capa_ate_Cap3.pdf: 3239359 bytes, checksum: 5d036616594887894c2008efe8619990 (MD5) Previous issue date: 2008-09-26 / This thesis deals with the tectonic-stratigraphic evolution of the Transitional Sequence in the Sergipe Sub-basin (the southern segment of the Sergipe-Alagoas Basin, Northeast Brazil), deposited in the time interval of the upper Alagoas/Aptian stage. Sequence boundaries and higher order internal sequences were identified, as well as the structures that affect or control its deposition. This integrated approach aimed to characterize the geodynamic setting and processes active during deposition of the Transitional Sequence, and its relations with the evolutionary tectonic stages recognized in the East Brazilian Margin basins. This subject addresses more general questions discussed in the literature, regarding the evolution from the Rift to the Drift stages, the expression and significance of the breakup unconformity, the relationships between sedimentation and tectonics at extensional settings, as well as the control on subsidence processes during this time interval. The tectonic-stratigraphic analysis of the Transitional Sequence was based on seismic sections and well logs, distributed along the Sergipe Sub-basin (SBSE). Geoseismic sections and seismic facies analysis, stratigraphic profiles and sections, were compiled through the main structural blocks of this sub-basin. These products support the depositional and tectonic-stratigraphic evolutionary models built for this sequence. The structural analysis highlighted similarities in deformation styles and kinematics during deposition of the Rift and Transitional sequences, pointing to continuing lithospheric extensional processes along a NW trend (X strain axis) until the end of deposition of the latter sequence was finished by the end of late Aptian. The late stage of extension/rifting was marked by (i) continuous (or as pulses) fault activity along the basin, controling subsidence and creation of depositional space, thereby characterizing upper crustal thinning and (ii) sagstyle deposition of the Transitional Sequence at a larger scale, reflecting the ductile stretching and thinnning of lower and sub crustal layers combined with an increasing importance of the thermal subsidence regime. Besides the late increments of rift tectonics, the Transitional Sequence is also affected by reactivation of the border faults of SBSE, during and after deposition of the Riachuelo Formation (lower section of the Transgressive Marine Sequence, of Albian age). It is possible that this reactivation reflects (through stress propagation along the newlycreated continental margin) the rifting processes still active further north, between the Alagoas Sub-basin and the Pernambuco-Para?ba Basin. The evaporitic beds of the Transitional Sequence contributed to the development of post-rift structures related to halokinesis and the continental margin collapse, affecting strata of the overlying marine sequences during the Middle Albian to the Maastrichtian, or even the Paleogene time interval. The stratigraphic analysis evidenced 5 depositional sequences of higher order, whose vertical succession indicates an upward increase of the base level, marked by deposition of continental siliciclastic systems overlain by lagunar-evaporitic and restricted marine systems, indicating that the Transitional Sequence was deposited during relative increase of the eustatic sea level. At a 2nd order cycle, the Transitional Sequence may represent the initial deposition of a Transgressive Systems Tract, whose passage to a Marine Transgressive Sequence would also be marked by the drowning of the depositional systems. At a 3rd order cycle, the sequence boundary corresponds to a local unconformity that laterally grades to a widespread correlative conformity. This boundary surface corresponds to a breakup unconformity , being equivalent to the Pre-Albian Unconformity at the SBSE and contrasting with the outstanding Pre-upper Alagoas Unconformity at the base of the Transitional Sequence; the latter is alternatively referred, in the literature, as the breakup unconformity. This Thesis supports the Pre-Albian Unconformity as marker of a major change in the (Rift-Drift) depositional and tectonic setting at SBSE, with equivalent but also diachronous boundary surfaces in other basins of the Atlantic margin. The Pre-upper Alagoas Unconformity developed due to astenosphere uplift (heating under high lithospheric extension rates) and post-dates the last major fault pulse and subsequent extensive block erosion. Later on, the number and net slip of active faults significantly decrease. At deep to ultra deep water basin segments, seaward-dipping reflectors (SDRs) are unconformably overlain by the seismic horizons correlated to the Transitional Sequence. The SDRs volcanic rocks overly (at least in part) continental crust and are tentatively ascribed to melting by adiabatic decompression of the rising astenospheric mantle. Even though being a major feature of SBSE (and possibly of other basins), the Pre-upper Alagoas Unconformity do not correspond to the end of lithospheric extension processes and beginning of seafloor spreading, as shown by the crustal-scale extensional structures that post-date the Transitional Sequence. Based on this whole context, deposition of the Transitional Sequence is better placed at a late interval of the Rift Stage, with the advance of an epicontinental sea over a crustal segment still undergoing extension. Along this segment, sedimentation was controled by a combination of thermal and mechanical subsidence. In continuation, the creation of oceanic lithosphere led to a decline in the mechanical subsidence component, extension was transferred to the mesoceanic ridge and the newly-formed continental margin (and the corresponding Marine Sequence) began to be controlled exclusively by the thermal subsidence component. Classical concepts, multidisciplinary data and new architectural and evolutionary crustal models can be reconciled and better understood under these lines / Esta tese aborda a evolu??o tectono-estratigr?fica da Seq??ncia Transicional na Subbacia de Sergipe (por??o sul da Bacia Sergipe-Alagoas, Nordeste do Brasil), depositada no intervalo que abrange o Alagoas superior. Foram identificadas as suas superf?cies lim?trofes e seq??ncias internas, de maior ordem, bem como as estruturas que a afetaram ou controlaram a sua deposi??o. Essa abordagem integrada teve como objetivo caracterizar o contexto geodin?mico e os processos atuantes durante a deposi??o desta seq??ncia e sua rela??o com os est?gios tect?nicos reconhecidos na evolu??o das bacias da Margem Leste Brasileira. O tema da tese remete a uma problem?tica amplamente discutida na literatura, envolvendo a passagem entre os est?gios Rifte e Drifte, a express?o e o significado da discord?ncia de breakup, a rela??o entre a sedimenta??o e o tectonismo em ambientes distensionais, bem como os controles dos processos de subsid?ncia neste intervalo de tempo. A an?lise tectono-estratigr?fica da Seq??ncia Transicional foi realizada com base em se??es s?smicas e perfis de po?os, distribu?dos ao longo da Sub-bacia de Sergipe (SBSE). Foram executadas se??es geoss?smicas e an?lise de sismof?cies, perfis e se??es estratigr?ficas, que recobrem os principais compartimentos estruturais desta sub-bacia. A partir desses produtos, foram elaborados modelos deposicionais e da evolu??o tectonoestratigr?fica da Seq??ncia Transicional. A an?lise estrutural demonstra semelhan?as no estilo e cinem?tica da deforma??o atuante durante a deposi??o das seq??ncias Rifte e Transicional, que apontam para uma continua??o dos processos de distens?o litosf?rica ao longo da dire??o NW (eixo de strain X), at? o final do Neo-Aptiano, quando se encerrou a deposi??o desta ?ltima. Os est?gios tardios da distens?o/rifteamento estariam marcados pela (i) cont?nua (embora em pulsos) atividade de falhas ao longo da bacia, controlando a cria??o do espa?o de acomoda??o nas suas imedia??es e caracterizando o afinamento da crosta superior, e (ii) deposi??o em estilo sag, quando a Seq??ncia Transicional ? visualizada numa escala mais ampla, refletindo o componente de estiramento e afinamento d?ctil de n?veis infra e subcrustais, combinado ? crescente import?ncia do regime de subsid?ncia t?rmica. Al?m da tect?nica rifte nos seus incrementos tardios, a Seq??ncia Transicional tamb?m se encontra afetada pela reativa??o das falhas de borda na SBSE, durante e ap?s a deposi??o da Forma??o Riachuelo (por??o inferior da Seq??ncia Marinha Transgressiva, de idade albiana). ? poss?vel que essa reativa??o constitua o reflexo (transmiss?o de tens?es ao longo da margem continental em forma??o) dos processos de rifteamento ainda ativos mais a norte, entre a Sub-bacia de Alagoas e a Bacia Pernambuco-Para?ba. As camadas evapor?ticas da Seq??ncia Transicional contribu?ram para o desenvolvimento de estruturas p?s-rifte, relacionadas ? halocinese e ao colapso da margem, as quais perturbam os estratos das seq??ncias marinhas sobrepostas num intervalo que se estende do Mesoalbiano ao Maastrichtiano, ou mesmo at? o Pale?geno. A an?lise estratigr?fica demonstrou a ocorr?ncia de 5 seq??ncias deposicionais de maior ordem, cuja sucess?o vertical indica um aumento progressivo do n?vel de base, marcado pela deposi??o dos sistemas silicicl?sticos continentais, que passam para sistemas lagunares-evapor?ticos e marinhos restritos, indicando que a Seq??ncia Transicional foi depositada num flanco de subida relativa do n?vel eust?tico. Num ciclo de 2? ordem, essa seq??ncia pode representar a deposi??o inicial de um Trato de Sistemas Transgressivo, cuja passagem para a Seq??ncia Marinha Transgressiva tamb?m estaria marcada por um afogamento dos sistemas deposicionais. Num ciclo de 3? ordem, a passagem entre estas seq??ncias ? balizada por uma discord?ncia restrita que lateralmente passa a uma concord?ncia correlativa, mais abrangente. Esta passagem corresponde ? discord?ncia de breakup , equivalente ? Discord?ncia Pr?-Albiano na SBSE, e contrasta com a maior express?o da Discord?ncia Pr?-Alagoas superior, esta ?ltima na base da Seq??ncia Transicional e alternativamente referida, na literatura, como a discord?ncia de breakup. Nesta Tese, ? adotado o conceito de que a Discord?ncia Pr?-Albiano seria o marco da mudan?a de contexto deposicional e do ambiente tect?nico (Rifte-Drifte) na SBSE, com superf?cies equivalentes mas tamb?m di?cronas, em outras bacias da Margem Atl?ntica. A Discord?ncia Pr?-Alagoas superior teria se formado em resposta ? subida da astenosfera (aquecimento sob altas taxas de distens?o litosf?rica) e p?s-data o ?ltimo pulso importante de falhamentos (a ela sotopostos) e eros?o de blocos. Acima dela, o n?mero de falhas ativas e o seu rejeito decresceram significativamente. Em ?guas profundas a ultraprofundas, os seaward-dipping reflectors (SDRs) s?o capeados em discord?ncia pelos horizontes s?smicos correlatos ? Seq??ncia Transicional. Essas rochas vulc?nicas foram (pelo menos parcialmente) alojadas sobre crosta continental, sendo tentativamente atribu?das ? fus?o do manto astenosf?rico em processo de subida e descompress?o adiab?tica. Embora seja uma fei??o muito importante na SBSE (e possivelmente, em outras bacias), a Discord?ncia Pr?-Alagoas superior n?o delimita o final do processo de distens?o litosf?rica e o in?cio de cria??o de assoalho oce?nico, haja vista as evid?ncias de estruturas distensionais de escala (pelo menos) crustal, que afetam a Seq??ncia Transicional. Considerando todo esse contexto, a deposi??o da Seq??ncia Transicional ? melhor posicionada no intervalo tardio do Est?gio Rifte, com a entrada de um mar epicontinental sobre o segmento de crosta ainda em processo de distens?o. Ao longo deste segmento, a sedimenta??o estaria ent?o controlada pela combina??o de subsid?ncia t?rmica e mec?nica. Em seq??ncia, o in?cio de cria??o de litosfera oce?nica conduziu ao decl?nio do componente de subsid?ncia mec?nica, a distens?o foi transferida para a cadeia mesoce?nica e a margem continental em forma??o (e a correspondente Seq??ncia Marinha) passou a ser controlada exclusivamente pelo componente de subsid?ncia t?rmica. Conceitos cl?ssicos, dados multidisciplinares e novos modelos arquiteturais e de evolu??o da crosta podem ser reconciliados e melhor compreendidos sob as linhas discutidas

Made available in DSpace on 2015-02-24T19:48:39Z (GMT). No. of bitstreams: 1 AlexFA_ate_Cap4.pdf: 3915510 bytes, checksum: 709e53f554fdeeeefb4020512e95ef8b (MD5) Previous issue date: 2004-07-26 / The Xar?u Oil Field, located in the center-southern portion of the Munda? Sub-Basin (eastern portion of the Cear? Basin), is characterized by a main Iramework of NW-trending and NE-dipping faults. The faults in the Xar?u Oil Field, among which the Xar?u Fautt stands out, are arranged according to an extensional-listriclan, rooted on a detachment surface corresponding to the Munda? Fault, the border fautt of Munda? Sub-Basin. During the tectonic-structural evolution of the Xar?u Oil Field and the Munda? Sub-Basin, the Munda? Fault played a crucial role on the control of the geometry of both compartments. The main carbonatic unit in the Xar?u Oil Field, named the Trair? Member(Paracuru Formation of Late Aptian to Early Albian age), contains the largest oil volume in the field, concentrated in structurally-controlled accumulations. The Trair? Member is composed by a variety of carbonatic rocks (massive, bedded or laminated calcilutites, ostracodites, calcarenites and carbonatic rudites, all of them presenting variable degrees of dolomitization). The carbonatic rocks are interbedded into thick packages of black shales and marls, besides local beds of siliciclastic conglomerates, sandstones, siltnes and argillites. From the spatial association and the genetic relationships between the carbonatic and siliciclastic units, it is possible to group them in three lithofacies associations (Marginal Plain, Ramp and Lacustrine Interior) that, together, were developed in a lacustrine system associated to a marginal sabkha. Structural studies based on drill coresthat sample the Trair? Member in the Xar?u Oil Field allowed to characterize two generations of meso- to microscale structures: the D1 group presents a typical hydroplastic character, being characterized by intra/interstratal to oblique-bedding shear zones. The hydroplastic character related to these structures allowed to infer their development at an early-lithilication stage of the Trair? Member, leading to infer an Early Cretaceous age to them. The second group of structures identified in the drill cores, nominated D2 and ascribed to a Neogene age, presents a strictly brttle character, being typilied by normal faults and slickenfibers of re-crystallized clayminerals, ali olthem displaying variable orientations. Although the present faults in the Xar?u Oil Field (and, consequently, in the Munda? Sub-Basin) were classically relerred as struetures of essentially normal displacement, the kinematics analysis of the meso-to microscaie D1 struetures in the drill cores led to deline oblique displacements (normal with a clockwise strike-slip component) to these faults, indicating a main tectonic transport to ENE. These oblique movements would be responsible for the installation of a transtensive context in the Munda? Sub-Basin, as part of the transcurrent to translormant opening of the Atlantic Equatorial Margin. The balancing of four struetural cross-sections ofthe Xar?u Oil Field indicates that the Munda? Fault was responsible for more than 50% of the total stretching (? factor) registered during the Early Aptian. At the initial stages of the "rifting", during Early Aptianuntil the Holocene, the Munda? Sub-Basin (and consequently the Xar?u Oil Fleld) accumulated a total stretching between 1.21 and 1.23; in other words, the crust in this segment of the Atlantic Equatorial Margin was subjeeted to an elongation of about 20%. From estimates of oblique displacements related to the faults, it ws possible to construct diagrams that allow the determination of stretching factors related to these displacements. Using these diagrams and assuming the sense 01 dominant teetonictransport towards ENE, it was possible to calculate the real stretching lactors related to the oblique movement 0 of the faults in the Munda? Sub-Basin. which reached actual values between 1.28 and 1.42. ln addnion to the tectonic-structural studies in the Xar?u Oil Field, the interpretation of remote sensing products, coupled wnh characterization of terrain analogues in seleeted areas along the northern Cear? State (continental margins of the Cear? and Potiguar basins), provided addnional data and constraints about the teetonic-structural evolution of the oil lield. The work at the analogue sites was particularly effective in the recognition and mapping, in semidetail scale, several generations of struetures originated under a brittle regime. Ali the obtained information (from the Xar?u Oil Field, the remote sensor data and the terrain analogues) were jointly interpreted, culminating with the proposnion of an evolutionary model lor this segment of the Atlantic Equatorial Margin; this model that can be applied to the whole Margin, as well. This segmentof the Atlantic Equatorial Margin was delormedin an early E-W (when considered lhe present-day position of the South American Plate) transcurrent to transform regime with dextral kinematics, started Irom, at least, the Early Aptian, which left its record in several outcrops along the continental margin of the Cear? State and specilically in the Xar?u off Field. The continuous operation of the regime, through the Albian and later periods, led to the definitive separation between the South American and African plates, with the formation of oceanic lithosphere between the two continental blocks, due to the emplacement off spreading centers. This process involved the subsequent transition of the transcurrent to a translorm dextral regime, creating lhe Equatorial Atlantic Oceano With the separation between the South American and African plates already completed and the increasing separation between lhe continental masses, other tecton ic mechanisms began to act during the Cenozoic (even though the Cretaceous tectonic regime lasted until the Neogene), like an E-W compressive stress l?eld (related to the spreading olthe oceanic floor along lhe M id-Atlantic Ridge and to the compression of the Andean Chain) effective Irom the Late Cretaceous, and a state of general extension olthe horizontal surface (due to the thermal uplift ofthe central portion of Borborema Province), effective during the Neogene. The overlap of these mechanisms during the Cenozoic led to the imprint of a complex tectonic framework, which apparently influenced the migration and entrapment 01 hydrocarbon in the Cear? Basin

Made available in DSpace on 2015-02-24T19:48:40Z (GMT). No. of bitstreams: 1 1-44.pdf: 5231918 bytes, checksum: eda1e7c0b224ead6ae01660a9c2ee531 (MD5) Previous issue date: 2009-10-16 / The northern coast of Rio Grande do Norte State is characterized by strong changes in coastal morphology, caused by various geological and climatic factors. In this region are installed the main socio-economic activities of the State, highlighting the oil industry, which exerts much of its activities in the coastal area studied. Erosion is a constant problem in this region because it affects the entire local populace to the destruction of houses and trade, rendering tourism, affecting the livelihood activities and industrial activities. The greatest risk is related to environmental damage that can be caused by the oil spill in this region. To understand what determines the changes in coastal morphology this Doctoral Thesis is proposed to identify the factors at local, regional and even global corroborate coastal dynamics to this coast in question. For this study, used several different products and tools for interpreting the conditions of the erosive effect that dominates the whole northern coast of the State, in an attempt to quantify and describe the causes and effects that affect the entire coastal zone monitored. The development of activities is built into the projects Rede 05 PETROMAR (CTPETRO-FINEP/PETROBRAS/CNPq), PETRORISCO, HIDROSEMA, PETROMAR e Rede 05/04 POTMAR (FNDCT/CTPETROFINEP/ CNPq), in the activities of multidisciplinary and inter-features in issues involving environmental monitoring and oil activity / O litoral setentrional do Estado do Rio Grande do Norte ? caracterizado por fortes mudan?as na sua morfologia costeira, ocasionadas por diversos fatores geol?gicos e clim?ticos. Nesta regi?o est?o instaladas as principais atividades socioecon?micas do Estado, destacando a Ind?stria Petrol?fera, que exerce boa parte de suas atividades na zona costeira estudada. A eros?o ? o constante problema nesta regi?o, pois afeta toda popula??o local com a destrui??o de moradias e com?rcio, inviabilizando o turismo, comprometendo as atividades de subsist?ncia e as atividades industriais. O risco maior est? relacionado ao dano ambiental que pode ser causado pelo derramamento de ?leo nesta regi?o. Para entender o que condiciona estas modifica??es na morfologia costeira esta Tese de Doutorado se prop?s em identificar os fatores de escala local, regional e at? global que corroboram com a din?mica costeira para este litoral em quest?o. Para tal estudo foram utilizados diversos produtos e diversas ferramentas para interpreta??o das condicionantes do efeito erosivo que predomina como um todo o litoral setentrional do Estado, na tentativa de quantificar e qualificar as causas e efeitos que afetam toda zona costeira monitorada. O desenvolvimento das atividades est? inserido em projetos Rede 05 PETROMAR (CTPETROFINEP/PETROBRAS/CNPq), PETRORISCO, HIDROSEMA, PETROMAR e Rede 05/04 POTMAR (FNDCT/CTPETRO-FINEP/CNPq), no ?mbito das atividades de caracter?sticas multidisciplinares e interinstitucional em temas que envolvem o monitoramento ambiental e a atividade petrol?fera

Made available in DSpace on 2015-02-24T19:48:41Z (GMT). No. of bitstreams: 1 DeboraCS.pdf: 6420496 bytes, checksum: ebd9df40c6eb9bda305af703bea3048f (MD5) Previous issue date: 2003-02-14 / This thesis deals with the sedimentological/stratigraphic and structural evolution of the sedimentary rocks that occur in the NW continental border of the Potiguar Basin. These rocks are well exposed along coastal cliffs between the localities of Lagoa do Mato and Icapu?, Cear? State (NE Brazil). The sedimentological/stratigraphic study involved, at the outcrop scale, detailed facies descriptions, profile mapping of the vertical succession of different beds, and columnar sections displaying inferred lateral relationships. The approach was complemented by granulometric and petrographic analyses, including the characterization of heavy mineral assemblages. The data set allowed to recognize two kinds of lithological units, a carbonate one of very restricted occurrence at the base of the cliffs, and three younger, distinct siliciclastic units, that predominate along the cliffs, in vertical and lateral extent. The carbonate rocks were correlated to the late Cretaceous Janda?ra Formation, which is covered by the siliciclastic Barreiras Formation. The Barreiras Formation occurs in two distinct structural settings, the usual one with nondeformed, subhorizontal strata, or as tilted beds, affected by strong deformation. Two lithofacies were recognized, vertically arranged or in fault contacts. The lower facies is characterized by silty-argillaceous sandstones with low-angle cross bedding; the upper facies comprises medium to coarse grained sandstones, with conglomeratic layers. The Tibau Formation (medium to coarse-grained sandstones with argillite intercalations) occurs at the NW side of the studied area, laterally interlayered with the Barreiras Formation. Eolic sediments correlated to the Potengi Formation overly the former units, either displaying an angular unconformity, or simply an erosional contact (stratigraphic unconformity). Outstanding structural features, identified in the Barreiras Formation, led to characterize a neocenozoic stress field, which generated faults and folds and/or reactivated older structures in the subjacent late cretaceous (to paleogene, in the offshore basin) section. The structures recognized in the Barreiras Formation comprise two distinct assemblages, namely a main extensional deformation between the localities of Ponta Grossa and Redonda, and a contractional style (succeeded by oblique extensional structures) at Vila Nova. In the first case, the structural assemblage is dominated by N-S (N?20?Az) steep to gently-dipping extensional faults, displaying a domino-style or listric geometry with associated roll-over structures. This deformation pattern is explained by an E-W/WNW extension, contemporaneous with deposition of the upper facies of the Barreiras Formation, during the time interval Miocene to Pleistocene. Strong rotation of blocks and faults generated low-angle distensional faults and, locally, subvertical bedding, allowing to estimate very high strain states, with extension estimates varying between 40% up to 200%. Numerous detachment zones, parallel to bedding, help to acommodate this intense deformation. The detachment surfaces and a large number of faults display mesoscopic features analoguous to the ones of ductile shear zones, with development of S-C fabrics, shear bands, sigmoidal clasts and others, pointing to a hydroplastic deformation regime in these cases. Local occurrences of the Janda?ra limestone are controled by extensional faults that exhume the pre-Barreiras section, including an earlier event with N-S extension. Finally, WNWtrending extensional shear zones and faults are compatible with the Holocene stress field along the present continental margin. In the Vila Nova region, close to Icapu?, gentle normal folds with fold hinges shallowly pluging to SSW affect the lower facies of the Barreiras Formation, displaying an incipient dissolution cleavage associated with an extension lineation at high rake (a S>L fabric). Deposition of the upper facies siliciclastics is controlled by pull-apart graben structures, bordered by N-NE-trending sinistral-normal shear zones and faults, characterizing an structural inversion. Microstructures are compatible with tectonic deformation of the sedimentary pile, burried at shallow depths. The observed features point to high pore fluid pressures during deformation of the sediments, producing hydroplastic structures through mechanisms of granular flow. Such structures are overprinted by microfractures and microfaults (an essentially brittle regime), tracking the change to microfracturing and frictional shear mechanisms accompanying progressive dewatering and sediment lithification. Correlation of the structures observed at the surface with those present at depth was tested through geophysical data (Ground Penetrating Radar, seismics and a magnetic map). EW and NE-trending lineaments are observed in the magnetic map. The seismic sections display several examples of positive flower structures which affect the base of the cretaceous sediments; at higher stratigraphic levels, normal components/slips are compatible with the negative structural inversion characterized at the surface. Such correlations assisted in proposing a structural model compatible with the regional tectonic framework. The strong neogenepleistocene deformation is necessarily propagated in the subsurface, affecting the late cretaceous section (A?u and Janda?ra formations), wich host the hydrocarbon reservoirs in this portion of the Potiguar Basin. The proposed structural model is related to the dextral transcurrent/transform deformation along the Equatorial Margin, associated with transpressive terminations of E-W fault zones, or at their intersections with NE-trending lineaments, such as the Ponta Grossa-Fazenda Bel?m one (the LPGFB, itself controlled by a Brasiliano-age strike-slip shear zone). In a first step (and possibly during the late Cretaceous to Paleogene), this lineament was activated under a sinistral transpressional regime (antithetic to the main dextral deformation in the E-W zones), giving way to the folds in the lower facies of the Barreiras Formation, as well as the positive flower structures mapped through the seismic sections, at depth. This stage was succeeded (or was penecontemporaneous) by the extensional structures related to a (also sinistral) transtensional movement stage, associated to volcanism (Macau, Messejana) and thermal doming processes during the Neogene-Pleistocene time interval. This structural model has direct implications to hydrocarbon exploration and exploitation activities at this sector of the Potiguar Basin and its offshore continuation. The structure of the reservoirs at depth (A?u Formation sandstones of the post-rift section) may be controlled (or at least, strongly influenced) by the deformation geometry and kinematics characterized at the surface. In addition, the deformation event recognized in the Barreiras Formation has an age close to the one postulated for the oil maturation and migration in the basin, between the Oligocene to the Miocene. In this way, the described structural cenario represents a valid model to understand the conditions of hydrocarbon transport and acummulation through space openings, trap formation and destruction. This model is potentially applicable to the NW region of the Potiguar Basin and other sectors with a similar structural setting, along the brazilian Equatorial Atlantic Margin / Esta tese contempla a caracteriza??o sedimentol?gica/litoestratigr?fica e estrutural das rochas sedimentares na por??o continental NW da Bacia Potiguar, e que afloram em fal?sias no setor litor?neo compreendido entre as localidades de Lagoa do Mato e Icapu?, Cear? (NE do Brasil). Os estudos sedimentol?gicos /estratigr?ficos das unidades mapeadas, em escala de afloramento, envolveram descri??es faciol?gicas, levantamento de perfis com empilhamento vertical das diferentes camadas, e a constru??o de se??es colunares caracterizando as rela??es laterais observadas. Ainda foram realizados estudos granulom?tricos e petrogr?ficos, bem como a identifica??o das assembl?ias de minerais pesados. O conjunto desses dados permitiu identificar dois grupos de litologias, representados por uma unidade carbon?tica, que ocorre de forma restrita na base das fal?sias, e tr?s unidades silicicl?sticas, que predominam lateral e verticalmente, nas fal?sias. As rochas carbon?ticas, correlacionadas ? Forma??o Janda?ra, do Cret?ceo superior, s?o capeadas pelas rochas silicicl?sticas da Forma??o Barreiras. A Forma??o Barreiras ocorre em dois contextos estruturais distintos, sob a forma de estratos horizontalizados e n?o deformados, a situa??o mais usual, ou com camadas basculadas e afetadas por forte deforma??o. Foram individualizadas duas litof?cies, dispostas verticalmente em contatos normais, ou por falhas. A denominada f?cies inferior ? composta por arenitos s?ltico-argilosos com estratifica??o cruzada de baixo ?ngulo; a f?cies superior ? caracterizada por arenitos m?dios a grossos, maci?os, com intercala??es conglomer?ticas. No extremo NW da ?rea ocorre uma segunda unidade, a Forma??o Tibau (arenitos m?dios a grossos com intercala??es de argilitos), que est? lateralmente interdigitada com a Forma??o Barreiras. Finalmente, no topo das unidades anteriores ocorrem sedimentos e?licos correlacionados ? Forma??o Potengi. A discord?ncia na base desta ?ltima unidade (a Forma??o Potengi) torna-se n?tida quando os estratos sotopostos est?o basculados e falhados (discord?ncia angular). Para os demais casos, o contato ? erosional (discord?ncia estratigr?fica). Na ?rea estudada, chamam aten??o as fei??es estruturais identificadas na Forma??o Barreiras, que permitem caracterizar o campo de tens?es neocenoz?ico, que gerou falhas e dobras e/ou reativou estruturas mais antigas na se??o neocret?cica (a pale?gena, no setor offshore da bacia) subjacente. As fei??es estruturais identificadas nas rochas da Forma??o Barreiras permitem distinguir duas situa??es distintas, caracterizadas por uma deforma??o principal distensional, entre as localidades de Ponta Grossa e Redonda, e um estilo contracional (sucedido por estruturas distensionais obl?quas), em Vila Nova. No primeiro caso, as fei??es observadas envolvem falhas distensionais de dire??o N-S (N?20?Az), com mergulhos de alto a baixo ?ngulo. Em geral possuem arranjo em domin? ou geometria l?strica com estruturas roll-over associadas. Este padr?o deformacional pode ser explicado por uma distens?o E-W/WNW, contempor?nea ? deposi??o da f?cies superior da Forma??o Barreiras, no intervalo Mioceno-Pleistoceno. A pronunciada rota??o de blocos e falhas delimitantes, gerando falhas distensionais de baixo ?ngulo e, localmente, verticaliza??o do acamamento, traduz a forte magnitude deste evento, com estimativas que variam de 40% at? 200% de distens?o. S?o freq?entes as zonas de descolamento paralelas ao acamamento, que permitem acomodar a intensa deforma??o observada. As superf?cies de descolamento e boa parte das falhas exibem fei??es mesosc?picas an?logas ?s de zonas de cisalhamento d?ctil, com desenvolvimento de superf?cies S-C, shear bands, clastos sigmoidais e outras, caracterizando no caso um regime de deforma??o hidropl?stico. As ocorr?ncias localizadas do Calc?rio Janda?ra s?o condicionadas por falhas distensionais que exumam a se??o pr?-Barreiras, incluindo um evento precoce com distens?o N-S. Finalmente, s?o observadas zonas de cisalhamento e falhas distensionais com dire??o WNW, tardias, explicadas por um evento compat?vel com o campo de tens?es holoc?nico, neste setor da margem continental. Na regi?o de Vila Nova, pr?ximo a Icapu?, observam-se dobras suaves afetando a f?cies inferior da Forma??o Barreiras, com eixos mergulhando para SSW, planos incipientes de clivagem de dissolu??o e uma linea??o de estiramento de alto rake, compondo um fabric S>L. A deposi??o dos silicicl?sticos da f?cies superior ? controlada por estruturas de graben pullapart, delimitados por falhas e zonas de cisalhamento sinistrais-normais, com dire??o N-NE, caracterizando uma invers?o estrutural. Os aspectos microestuturais s?o compat?veis com deforma??o tect?nica em um contexto de soterramento raso do pacote sedimentar. As fei??es identificadas sugerem altas press?es de fluidos nos poros dos sedimentos, gerando microestruturas de car?ter hidropl?stico, indicativos da atua??o do mecanismo de fluxo granular. Tais estruturas s?o superpostas por microfraturas e microfalhas (car?ter mais fr?gil), o que denota a passagem para mecanismos de microfraturamento e deslizamento friccional, com a progressiva desidrata??o e litifica??o dos sedimentos. A correla??o das estruturas observadas em superf?cie com aquelas presentes em subsuperf?cie foi realizada a partir de dados geof?sicos (Ground Penetrating Radar, s?smica e mapa magn?tico). Devem ser destacados os lineamentos E-W e NE, observados no mapa magn?tico e, nas se??es s?smicas, os v?rios exemplos de estruturas em flor positiva, que afetam a base da se??o neocret?cea; em n?veis superiores, tamb?m s?o discern?veis rejeitos/componentes normais, o que seria compat?vel com a invers?o negativa caracterizada em superf?cie. Tais correla??es auxiliaram na proposi??o de um modelo estrutural compat?vel com o arcabou?o tect?nico regional. A deforma??o ne?gena-pleistoc?nica, de grande magnitude, est? necessariamente propagada em subsuperf?cie afetando, neste caso, a se??o neocret?cea (forma??es A?u e Janda?ra), hospedeira dos reservat?rios de hidrocarbonetos neste setor da Bacia Potiguar. O modelo estrutural proposto foi relacionado ? deforma??o transcorrente/transformante dextral da Margem Equatorial, associada com termina??es em transpress?o de zonas E-W, ou na interse??o destas com zonas NE, a exemplo do Lineamento Ponta Grossa-Fazenda Bel?m (o LPGFB, controlado por uma zona de cisalhamento transcorrente, de idade brasiliana). Numa primeira etapa (e possivelmente no Cret?ceo superior e Pale?geno), este lineamento funcionou em regime transpressional sinistral (antit?tico ? deforma??o dextral nas zonas E-W), e pode ter gerado as dobras na f?cies inferior da Forma??o Barreiras, bem como as estruturas em flor positiva em subsuperf?cie. Este est?gio foi sucedido (ou foi penecontempor?neo) pelas estruturas distensionais que sugerem uma etapa de movimenta??o transtracional (tamb?m sinistral) associada a processos de vulcanismo (Macau, Messejana) e domeamento t?rmico, no intervalo Ne?geno-Pleistoceno. Este modelo estrutural tem implica??es diretas nas atividades de explora??o e de explota??o de hidrocarbonetos neste setor da Bacia Potiguar e em sua extens?o offshore. A estrutura??o dos reservat?rios em subsuperf?cie (arenitos da Forma??o A?u, da sequ?ncia p?srifte) pode estar condicionada (ou pelo menos, fortemente influenciada) pela geometria e cinem?tica da deforma??o, caracterizada em superf?cie. Em adi??o, o evento deformacional registrado na Forma??o Barreiras tem idade pr?xima ? da janela de matura??o e migra??o de ?leo na bacia, estimada entre o Oligoceno e o Mioceno. Desta forma, o cen?rio estrutural descrito representa um modelo v?lido para entender as condi??es de transporte e aprisionamento de hidrocarbonetos, promovendo abertura de espa?os, forma??o e destrui??o de trapas. Este modelo ? potencialmente aplic?vel ? regi?o NW da Bacia Potiguar e a setores com contexto estrutural semelhante, ao longo da Margem Equatorial Atl?ntica brasileira

Made available in DSpace on 2015-03-13T17:08:09Z (GMT). No. of bitstreams: 1 AntonioSAC.pdf: 751035 bytes, checksum: 1294e0bc4f14d547a8e585ebc00bb3a8 (MD5) Previous issue date: 2006-11-27 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The region of the Senador Pompeu Shear Zone (SPSZ), in the North Tectonic Domain of the Borborema Province (BP), has its recent history associated with to South Atlantic Ocean formation event at the Jurassic. A lot of geologics models have discussed about crustal axis elevation in local scale and large scale (Borborema Province), relative to importants regionals tectonics directions of it. The identification and the relationship among this surfaces, stepped in many topographyc levels by tectonics mecanisms, is dificult because of the erosion process on it. Over there, sedimentary deposits is complex and it has not biostratigraphyc record in continental deposits. The analysis metodology on apatita fission-track, in the region of the SPSZ, purpose the more knowledge about morphotectonics mecanisms of the area and the impruvement of its morphotectonics models. For this, it was moleled the age and thermal history of the 11 apatites samples collected on both sides of this shear zone, taking relationships among other results of the thermochronology studies in the BP. Based on the thermal studies in this search, the region of the BP developed on two distint cooling events, separated for one period of relative stabilited. The first episode occur between 130 and 90 M.y., has been began when the samples cross the 120?C isoterm for last time and fineshed at 70?C. The second moment of the cooling process was began about 30 M.y., when the temperature was 90?C, from this to the equlibrium with present surface temperature at 30?C. Some evidences indicated a relacionship between thermal episodes and uplift events of the regional relief. The fundaments of the interpretation was based mainly on comparatives studies among results of the thermochronology analysis and geologics studies about BP. N?brega et al.(2005), e.g., on studies about the Portalegre Shear Zone, got similar results on SPSZ, with some details relative to local tectonic activity. Morais Neto et al. (2000) interpreted two importants cooling events in the BP based on their regional studies, that can be associated to regional uplift events. When Assine (1992) studied the stratigraphyc sequences of the Araripe Basin, in the south of Cear? state, conclude that the abrupt return to continentals condictions from the last sedimentar sequency (albiano-cenomaniane) indicate a regional uplift of the NE region of the Brazil at the 100 M.y., in the Albiano Intermediate/Superior. This ages are compatible to termal model of the SPSZ. This two periods of the thermal history of the BP are completely registered in the apatites samples just one age groups of the fission-track, that it is the most ancient age groups. This one suggest it has happened in response to heating before 75 M.y and it has erased the last report of the first moment relief evolution of the BP. The NNE-SSW and E-W structure reativation can have created ideal condictions for heating and local elevations of the geothermal gradients. The equilibrium between the apatites temperatures of this groups and the regionais temperatures took place about 50 M.y., when the samples of the two ages groups had a simillar evolution to present surfaces temperatures / A regi?o da Zona de Cisalhamento Senador Pompeu (ZCSP), no Dom?nio Tect?nico Setentrional da Prov?ncia Borborema (PB), t?m sua hist?ria mais recente relacionada principalmente ao evento de forma??o do Oceano Atl?ntico Sul no fim do Jur?ssico. Diversos modelos geol?gicos t?m discutido a exist?ncia de eixos de arqueamento crustal, tanto em escala local como na escala do n?cleo nordestino, relacionados ?s principais dire??es tect?nicas regionais. A identifica??o e a correla??o entre estas superf?cies, tectonicamente reorganizadas em diversos n?veis topogr?ficos, ? dificultada em raz?o do adiantado processo de desmonte a que foram submetidas. Al?m disto, a distribui??o dos registros sedimentares ? complexa e h? uma car?ncia de registros bio-estratigr?ficos em dep?sitos continentais. A metodologia de an?lise por tra?os de fiss?o em apatita, na regi?o da ZCSP, buscou um melhor entendimento dos mecanismos e o aperfei?oamento dos modelos de evolu??o morfo-tect?nica elaborados para a ?rea em foco. Com este fim, foram modeladas a idade e a hist?ria t?rmica de 11 amostras de apatita, coletadas em ambos os lados desta zona de cisalhamento, estabelecendo-se a correla??o com os resultados obtidos por outros estudos termocronol?gicos realizados na PB. De acordo com o modelo termal obtido nesta pesquisa, a regi?o da PB se desenvolveu em dois epis?dios distintos de resfriamento, intercalados por um per?odo de relativa estabilidade. O primeiro epis?dio ocorreu entre 130 e 90 Ma, tendo sido iniciado quando as amostras cruzaram pela ?ltima vez a isoterma de 120?C e encerrado em 70?C. O segundo momento do processo de resfriamento foi iniciado aproximadamente em 30 Ma, quando a temperatura era de 90?C, tendo se estendido at? o equil?brio com as temperaturas atuais da superf?cie em 30?C. Algumas evid?ncias indicaram uma rela??o entre os epis?dios termais e eventos de soerguimento do relevo regional. Os fundamentos desta interpreta??o foram tra?ados principalmente atrav?s de estudos comparativos entre resultados de an?lises termocronol?gicas e de estudos geol?gicos na PB. N?brega et al. (2005), e.g., em estudos realizados na Zona de Cisalhamento Portalegre, chegaram a resultados similares aos alcan?ados na ZCSP, com algumas particularidades relacionadas ? atividade tect?nica local. Morais Neto et al. (2000) tamb?m interpretou em seus estudos regionais a ocorr?ncia de dois importantes eventos de resfriamento na PB, que podem estar relacionados a eventos de soerguimento regional. Assine (1992), ao estudar as seq??ncias estratigr?ficas da Bacia Araripe no sul do Cear?, concluiu que o abrupto retorno ?s condi??es continentais reinantes durante a sedimenta??o da ?ltima seq??ncia (albiana-cenomaniana) evidencia um soerguimento da regi?o NE do Brasil h? aproximadamente 100 Ma, no Albiano M?dio/Superior. Estas idades s?o compat?veis com o modelo termal da ZCSP. Estes dois per?odos da hist?ria t?rmica da PB est?o integralmente registrados nas amostras de apatita de apenas um dos grupos de idades de tra?os de fiss?o, compreendendo as idades mais antigas. Este fato foi atribu?do a um aquecimento anterior a 75 Ma, que pode ter obliterado o registro nestas amostras do primeiro momento da evolu??o do relevo da PB. A reativa??o de estruturas NNE-SSW e E-W pode ter criado as condi??es ideais para este aquecimento e eleva??o dos gradientes geot?rmicos locais. O equil?brio entre as temperaturas das apatitas deste grupo com as condi??es geot?rmicas regionais ocorreu por volta de 50 Ma, situa??o em que as amostras dos dois grupos de idade seguiram uma evolu??o similar at? as temperaturas atuais de superf?cie

Made available in DSpace on 2015-03-13T17:08:11Z (GMT). No. of bitstreams: 1 EdgarRHF.pdf: 2264577 bytes, checksum: e51665295f290a9fc195ade872b55719 (MD5) Previous issue date: 2006-08-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This dissertation focuses on rock thermal conductivity and its correlations with petrographic, textural, and geochemical aspects, especially in granite rocks. It aims at demonstrating the relations of these variables in an attempt to enlighten the behavior of thermal effect on rocks. Results can be useful for several applications, such as understanding and conferring regional thermal flow results, predicting the behavior of thermal effect on rocks based upon macroscopic evaluation (texture and mineralogy), in the building construction field in order to provide more precise information on data refinement on thermal properties emphasizing a rocky material thermal conductivity, and especially in the dimension stone industry in order to open a discussion on the use of these variables as a new technological parameter directly related to thermal comfort. Thermal conductivity data were obtained by using Anter Corporation s QuicklineTM -30 a thermal property measuring equipment. Measurements were conducted at temperatures ranging between 25 to 38 OC in samples with 2cm in length and an area of at least 6cm of diameter. As to petrography data, results demonstrated good correlations with quartz and mafics. Linear correlation between mineralogy and thermal conductivity revealed a positive relation of a quartz percentage increase in relation to a thermal conductivity increase and its decrease with mafic minerals increase. As to feldspates (K-feldspate and plagioclase) they show dispersion. Quartz relation gets more evident when compared to sample sets with >20% and <20%. Sets with more than 20% quartz (sienogranites, monzogranites, granodiorites, etc.), exhibit to a great extent conductivity values which vary from 2,5 W/mK and the set with less than 20% (sienites, monzonites, gabbros, diorites, etc.) have an average thermal conductivity below 2,5 W/mK. As to textures it has been verified that rocks considered thick/porphyry demonstrated in general better correlations when compared to rocks considered thin/medium. In the case of quartz, thick rocks/porphyry showed greater correlation factors when compared to the thin/medium ones. As to feldspates (K-feldspate and plagioclase) again there was dispersion. As to mafics, both thick/porphyry and thin/medium showed negative correlations with correlation factor smaller than those obtained in relation to the quartz. As to rocks related to the Streckeisen s QAP diagram (1976), they tend to fall from alcali-feldspates granites to tonalites, and from sienites to gabbros, diorites, etc. Thermal conductivity data correlation with geochemistry confirmed to a great extent mineralogy results. It has been seen that correlation is linear if there is any. Such behavior could be seen especially with the SiO2. In this case similar correlation can be observed with the quartz, that is, thermal conductivity increases as SiO2 is incremented. Another aspect observed is that basic to intermediate rocks presented values always below 2,5 W/mK, a similar behavior to that observed in rocks with quartz <20%. Acid rocks presented values above 2,5 W/mK, a similar behavior to that observed in rocks with quartz >20% (granites). For all the other cases, correlation factors are always low and present opposite behavior to Fe2O3, CaO, MgO, and TiO2. As to Al2O3, K2O, and Na2O results are not conclusive and are statistically disperse. Thermal property knowledge especially thermal conductivity and its application in the building construction field appeared to be very satisfactory for it involves both technological and thermal comfort aspects, which favored in all cases fast, cheap, and precise results. The relation between thermal conductivity and linear thermal dilatation have also shown satisfactory results especially when it comes to the quartz role as a common, determining phase between the two variables. Thermal conductivity studies together with rocky material density can function as an additional tool for choosing materials when considering structural calculation aspects and thermal comfort, for in the dimension stone case there is a small density variation in relation to a thermal conductivity considerable variation / Esta disserta??o aborda o tema condutividade t?rmica de rochas e sua correla??o com aspectos petrogr?ficos, texturais e geoqu?micos principalmente em rochas gran?ticas. O intuito ? demonstrar as rela??es destas vari?veis tentando elucidar o comportamento do efeito t?rmico nas rochas. Os resultados poder?o ser ?teis em diversas aplica??es, por exemplo, no entendimento e aferi??o de resultados de fluxo t?rmicos regionais, na predi??o do comportamento t?rmico de rochas baseados na avalia??o macrosc?pica (textura e mineralogia), no segmento de constru??o civil com o objetivo de fornecer informa??es mais precisas no que diz respeito ao refinamento de dados sobre propriedades t?rmicas enfatizando a condutividade t?rmica de materiais rochosos e ainda especialmente na ind?stria de rochas ornamentais com o objetivo de se abrir uma discuss?o sobre a utiliza??o destas vari?veis como novo par?metro tecnol?gico diretamente relacionado ao conforto t?rmico. Os dados de condutividade t?rmica foram obtidos a partir de um equipamento medidor de propriedades t?rmicas da marca Anter Corporation, modelo QuicklineTM -30. As medidas foram realizadas a temperaturas variando entre 25 e 38 OC em amostras com 2cm de espessura e ?rea com pelo menos 6cm de di?metro. Quanto aos dados petrogr?ficos os resultados demonstraram haver boas correla??es com o quartzo e m?ficos. A correla??o linear entre a mineralogia e a condutividade t?rmica revelou uma rela??o positiva do aumento da condutividade t?rmica em fun??o do aumento da percentagem de quartzo e diminui??o com o aumento de minerais m?ficos. J? os feldspatos (K-feldspato e plagiocl?sio) mostram dispers?o. A rela??o do quartzo fica mais evidente quando s?o comparados os conjuntos de amostras com >20% e <20%. O conjunto com mais de 20% de quartzo (sienogranitos, monzogranitos, granodioritos, etc.), exibe em sua grande maioria, valores de condutividade que variam acima de 2,5 W/mK, j? o conjunto com menos de 20% (sienitos, monzonitos, gabros, dioritos, etc.) tem condutividade t?rmica m?dia abaixo de 2,5 W/mK. Quanto as texturas verificou-se que os litotipos considerados grossos/porfir?ticos demonstraram no conjunto geral melhores correla??es quando comparados com os litotipos considerados finos/m?dios. No caso do quartzo os litotipos grossos/porfir?ticos mostraram maior fator de correla??o, quando comparados com os finos/m?dios. Quanto aos feldspatos (K-feldspato e plagiocl?sio) houve novamente dispers?o. Para os m?ficos, tanto os tipos grossos/porfir?ticos quanto os finos/m?dios, mostraram correla??es negativas com fator de correla??o menor do que os obtidos em rela??o ao quartzo. Quanto aos litotipos, relacionados ao diagrama QAP de Streckeisen (1976), h? uma tend?ncia de queda no sentido dos alcali-feldspatos granitos para os tonalitos, e dos sienit?ides para os gabros, dioritos, etc. A correla??o dos dados de condutividade t?rmica com os de geoqu?mica confirmou em grande parte, os resultados de mineralogia. Observou-se que a correla??o, quando existe, ? linear. Este comportamento foi verificado principalmente com o SiO2. Neste caso nota-se uma correla??o similar a observada com o quartzo, ou seja, aumento da condutividade t?rmica com o incremento de SiO2. Um outro aspecto observado ? que rochas b?sicas a intermedi?rias apresentaram valores sempre inferiores a 2,5 W/mK, comportamento similar ao observado em rochas com quartzo <20%. J? as rochas ?cidas apresentaram valores acima de 2,5 W/mK, comportamento similar ao observado em rochas com quartzo >20% (gran?ticas). Nos demais casos os fatores de correla??o s?o sempre baixos apresentando comportamento inverso, sendo observado para Fe2O3, CaO, MgO, e TiO2. Quanto ao Al2O3, K2O e Na2O os resultados n?o s?o conclusivos havendo estatisticamente dispers?o. O conhecimento das propriedades t?rmicas em especial a condutividade t?rmica e sua aplica??o na constru??o civil mostrou-se bastante satisfat?ria, pois, envolve tanto aspectos tecnol?gicos quanto aspectos do conforto t?rmico favorecendo em todos os casos resultados r?pidos, baratos e precisos. A rela??o da condutividade t?rmica, com a dilata??o t?rmica linear tamb?m mostrou resultados satisfat?rios em especial quando fica demonstrado o papel do quartzo como fase comum e determinante entre as duas vari?veis. O estudo da condutividade t?rmica aliada a densidade dos materiais rochosos poder? servir como ferramenta adicional na escolha de materiais quando se levar em considera??o aspectos do c?lculo estrutural e do conforto t?rmico, pois no caso das rochas ornamentais h? uma pequena varia??o da densidade em detrimento da varia??o consider?vel da condutividade t?rmica

Made available in DSpace on 2015-03-13T17:08:13Z (GMT). No. of bitstreams: 1 SandroGFAG.pdf: 1252298 bytes, checksum: 72f92e485f189074de48f58893f848c0 (MD5) Previous issue date: 2007-03-30 / This dissertation presents a study on crustal seismic anisotropy in Cascavel - CE. The earthquake data employed here are from the Seismological Laboratory at Universidade Federal do Rio Grande do Norte (UFRN) and were colected from 29 September 1997 to 05 march 1998 using six three-component digital seismographic stations. In general, the cause of the observed seismic anisotropy in many regions of the world is interpreted in terms of fluid-filled stress aligned microcracks in the rockmass (EDA). In other words, the polarisation direction of the faster shear-wave splitting is parallel to SHmax. However, other researches on seismic anisotropy carried out in NE Brazil have shown a remarkable consistency of the faster shear-wave polarisation direction with the direction of the Precambrian fabric. The present work is another case study that is used to investigate this issue. In order to map the Precambrian fabric we used aeromagnetic data, since the study area is mostly covered with sediments (up to 50m thick) and in-situ field mapping would be very difficult to be carried out. According to the results from the present research, the observations of the faster shear-wave polarisation directions in two seismographic stations in Cascavel region are best explained in the framework of EDA. For the remaining two stations, the observed anisotropy may have two interpretions: (i) - 90_ flips of the direction of polarisation of the faster shear-wave, since that the event-to-station ray path would be through the fracture zone and hence would travel under a higher pore pressure and (ii) - the observed seismic anisotropy would agree with the direction on the ductile Precambrian fabric / Este trabalho apresenta um estudo sobre a anisotropia s?smica crustal na regi?o de Cascavel - CE. Para tal an?lise, foram utilizados os dados, cedidos pelo Laborat?rio Sismol?gico da UFRN, coletados durante o per?odo de 29 de setembro de 1997 a 05 de mar?o de 1998, atrav?s de uma rede sismogr?fica digital de tr?s componentes, composta por seis esta??es. Freq?entemente, a causa da anisotropia s?smica crustal em in?meras regi?es do mundo, ? interpretada como sendo efeito do alinhamento de poros e microfraturas saturados por fluidos, induzido pelo regime de esfor?o atual (EDA). Recentemente, pesquisas realizadas na regi?o Nordeste do Brasil apresentaram uma interpreta??o cujos resultados para as observa??es da anisotropia crustal, apontaram uma consist?ncia das dire??es de polariza??o da onda S mais r?pida (onda S1), com a petrotrama d?ctil pr?-cambriana. Para o mapeamento dos lineamentos pr?-cambrianos na regi?o, usamos os resultados obtidos da assinatura magn?tica da ?rea, j? que a mesma ? coberta por sedimentos (de at? 50m de espessura), tornando dif?cil o mapeamento desses alinhamentos em campo. Observa??es de dire??es de polariza??o da onda S mais r?pida obtidas por esta disserta??o, em quatro esta??es sismogr?ficas, para a regi?o de Cascavel - CE, mostram consist?ncia com o mecanismo da EDA para duas esta??es. Para as outras duas esta??es sismogr?ficas restantes, a anisotropia observada pode ter duas interpreta??es: (i) rota??o de 90_ na dire??o de polariza??o da onda S1, uma vez que os raios s?smicos percorreriam trajet?rias ao longo da zona de falha, e de a mesma estar sobre uma press?o de poro alta e (ii) - a anisotropia observada concordaria com a petrotrama d?ctil pr?-cambriana