Aspectos morfo-tect?nicos nos plat?s de Portalegre, Martins e Santana/RN
| Autor: | Barros, Silvana Diene Sousa |
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| Jazyk: | portugalština |
| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Repositório Institucional da UFRNUniversidade Federal do Rio Grande do NorteUFRN. |
| Druh dokumentu: | masterThesis |
| Popis: | Made available in DSpace on 2015-03-13T17:08:16Z (GMT). No. of bitstreams: 1 SilvanaDSB_ate o cap3.pdf: 2368599 bytes, checksum: 4c29280234b51f854200d0bf377f8c62 (MD5) Previous issue date: 1998-08-24 Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior A morpho-structural analysis was performed in the uplifted siliciclastic deposits of the Serra do Martins Formation along the Portalegre, Martins and Santana plateaux, in the southeastern and central regions of Rio Grande do Norte State. Due to the lack of biostratigraphic records, this formation has a disputable age.The adopted approach was based on the analysis of the drainage patterns and in the recognition of topographic surfaces and regional structures, subjected to neotectonic deformation and rejuvenation the present stress field. These events are recorded in the lineament arrays and as anomalous features of the landscape, such as the uplifted plateaux.The morpho-sculptural evolution of the studied blocks is expressed as erosive and accumulative processes. The former ones include erosional scarpments, cuestas and amphitheaters as the most characteristic features, while debris slopes represent acumulative examples. Such elements attest to the recent disequilibrium of the plateaux, and the absence of well developed alluvium terraces suggest an accelerated uplift process. The directions of the linear features observed in remote sensing products evidence the control of the basement structural trends, inherited from the pre-Cenozoic evolution. The NNE-SSW direction controls the main erosional features of the plateaux, while the N-S direction is a major drainage control, being also recognized in the Potiguar Basin. An E-W trend occurs as a less developed direction, reflecting either a system of mesozoic basic dykes or precambrian brittle structures. As regards to the drainage arrays, an arborescent, varying to a roughly N-S rectangular pattern, was identified in the Portalegre-Martins block. The Santana plateau displays rectilinear (northern border) and dendritic arborescent (southern border) patterns. In the sedimentary cover, the drainage pattern varies from rectangular to angular, reflecting inheritance from the crystaline basement. The most significative directions, N, NE and NW, mark the erosional fronts of the plateaux. Drainage anomalies, characterized by elbows or paralell confluencies, reinforce the arguments mentioned above. The data sets evidence the relationships between endogenous (lithology, structures) and exogenous features as the main controls of terrain dissecation, associated to vertical (epirogenesis) movements and horizontal tectonics. A final discussion addresses the relationships of the Serra do Martins Formation with the sedimentary record of Potiguar Basin, trying to establish chronostratigraphic links with the main evolutionary steps of this part of the Borborema Province, and possible mechanisms involved in the uplift of the plateaux and other stratigraphic units in the region A an?lise morfo-tect?nica aqui apresentada teve por objetivo estudar os dep?sitos silicicl?sticos soerguidos da Forma??o Serra do Martins, no contexto dos plat?s de Portalegre, Martins e Santana, situados nas por??es sudoeste e central do Estado do Rio Grande do Norte. A referida forma??o tem idade discut?vel, por n?o apresentar registros crono e/ou bioestratigr?ficos que a posicionem temporalmente. A sistem?tica de investiga??o adotada fundamentou-se na an?lise da rede de drenagem, no reconhecimento de superf?cies topogr?ficas e das estruturas regionais, submetidas a eventos e reativa??es neotect?nicas. Estes aspectos t?m reflexo direto no arranjo dos lineamentos e em fei??es an?malas identificadas na paisagem, p. ex., os plat?s soerguidos. A evolu??o morfo-escultural dos blocos estudados est? expressa atrav?s de processos erosivos e acumulativos. Dentre as fei??es dissecativas as escarpas de eros?o, cuestas e anfiteatros s?o as mais caracter?sticas, enquanto que os debris slopes constituem um exemplo acumulativo marcante. Estes elementos marcam o desequil?brio recente dos plat?s, onde a aus?ncia de expressivos terra?os aluvionares reflete um processo de r?pido soerguimento. As dire??es das fei??es lineares observadas nos produtos de sensoriamento remoto evidenciam o controle dos trends estruturais do embasamento, herdados da evolu??o pr?-Cenoz?ica. A orienta??o NNE-SSW controla fei??es erosionais dos plat?s, e o trend N-S condiciona o arranjo da drenagem, sendo tamb?m reconhecido na Bacia Potiguar. O trend E-W ocorre de forma menos intensa, refletindo o sistema de diques b?sicos mesoz?icos ou estruturas fr?geis precambrianas. No tocante ao arranjo da drenagem, o padr?o arborescente com varia??es para retangular com dire??o geral para norte foi identificado no bloco Portalegre-Martins. O plat? de Santana ordena-se em padr?es retil?neo (borda norte) e dendr?tico arborescente (sul). Na cobertura sedimentar o arranjo varia de retangular a angular, refletindo o arcabou?o herdado do embasamento cristalino. As dire??es mais significativas s?o N, NE e NW, marcando os trends erosivos. As anomalias de drenagem caracterizadas por deflex?es em cotovelo ou conflu?ncias em arranjo paralelo refor?am os argumentos acima expostos. Os estudos evidenciam a rela??o dos fatores end?genos (litologia, fei??es estruturais) em combina??o aos ex?genos, como condicionantes do maior ou menor grau de disseca??o do relevo, associados aos movimentos verticais (epirog?nese) e ? tect?nica horizontal. S?o discutidas as v?rias possibilidades de correla??o da Forma??o Serra do Martins com os sedimentos encontrados na Bacia Potiguar emersa, objetivando estabelecer poss?veis conex?es crono-estratigr?ficas com os v?rios epis?dios evolutivos desta por??o da Prov?ncia Borborema, e os prov?veis mecanismos envolvidos no soerguimento destes plat?s e de outras unidades estratigr?ficas regionais |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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