2019-08-262019-08-262002-09-13COSTA, Antônio Roberto Almeida. Tectônica cenozóica e movimentação salífera na Bacia do Amazonas e suas relações com a geodinâmica nas placas da América do Sul, Caribe, Cocos e Nazca. Orientador: João Batista Sena Costa. 2002. 237 f. Dissertação (Mestrado em Geologia e Geoquímica) – Centro de Geociências, Universidade Federal do Pará, Belém, 2002. Disponível em: http://repositorio.ufpa.br/jspui/handle/2011/11530. Acesso em: .https://repositorio.ufpa.br/handle/2011/11530This research, based on seismic section interpretations, deals with the tectonic events and salt movement (halotectonic) that took place in the Amazonas Basin during the Cenozoic. The main structures have been compared with the tectonic signatures of the Solimões, Acre and Tacutu basins in order to understand the kinematic events that affected the sedimentary filling of those basins. The Amazonas, Solimões, Acre and Tacutu basins and some parts of the South American Plate underwent intraplate deformational events during the Cenozoic. From tectonic data of the Northern Andes and Caribbean area, including the northern South American Plate, and available kinematic models, it could be reached the integration of the stress field that originated the major tectonic elements that affected the sedimentary basins of the Amazon region, especially the western part of the Amazonas Basin. From Upper Miocene to Holocene the Northern Andes reached its current configuration. The Upper Miocene corresponds to the beginning of the uplift of the northeastern Andes and represents the most dynamic tectonic phase of the Miocene. The main landforms of the Andean chain developed during the Miocene and few changes have occurred since then. The complex structural pattern of the northern South America is related to the oblique compressive stress in the plate margin that imposed deformation on the convergent systems of the Cretaceous and Paleocene, when South America has been pushed against the Caribbean and Nazca plates. The intraplate stress field data of the northern South America are still few to support the best characterization of the regional pattern of this long and vast area, which is marked by a high diversity and complex tectonic setting. The intraplate stress field seems to be the result of the action of local and regional forces in the lithosphere. Local stress pattern could be due to the structural heterogeneities, the increase and reduction of crustal load and the thermal anomalies from astenosphere. The regional forces are more uniform and directly related to the plates driving forces, such as: the force due to the spreading of the ocean floor (ridge-push); negative fluctuation of the subducted plate and forces of viscous shearing in the lithosphere-astenosphere boundary. The Juruá tectonic event was the most important mesozoic deformation that affected the Paleozoic Solimões and Amazonas Basins. The transpressive structures generated during this event are those revealed as petroleum traps, mainly in the Solimões Basin. From seismic interpretation of the Amazonas basin, it was demonstrated important structural style variation from region to region. Some areas show weak deformation while others are characterized by complex structures. On base of this criteria, the basin was divided into three structural domains, identified as North, South and Central domains and comprising 8 (eight) structural sectors. The North Domain includes the following sectors: Negro-Trombetas River and Curuá River; the South Domain comprises Canumã River, Mamuru River and Cupari River sectors; and the Central Domain includes Madeira River, Abacaxis-Tapajós River and Jurupari River sectors. Two tectonic events were characterized from seismic interpretations of the Amazonas Basin. The first was characterized only in the Manaus Platform area. The second is probably of Pliocene in age and it is characterized by folds and faulted blocks related to the transpressive system that affects post-Paleozoic sequences. The largest diversity and structural complexity were identified along the Abacaxis-Tapajós River sector, between the Central Domain and the boundaries of the North and South Domains. It is also in this area that occur the most important halotectonic features, as the salt pillows. The development of these features is mainly controlled by Cenozoic strike-slip tectonic events that caused the reactivation of ancient ductile zones and originated faults that cut the Amazonas Basin in the NE-SW and NW-SE directions; the largest thickness of the halite layers that occur in this region; the gravitational instability due to the differential load caused by diabase sills; and the steep dips of the layers. The halotectonic could have controlled the development of some relief features and part of the drainage systems of the Amazonas basin. The irregular and complex folds seen in the evaporitic sequence of the Nova Olinda Formation resulted from the high plastic behavior and tectonic mobility of the salt layers. Frequently the seismic layers under the sequence that contains halite are undeformed. But once deformed, they show different structural styles from those of the interval that contains halite. The structural styles in the platform areas (Manaus e Abacaxis-Mamuru) show geometric characteristics (transpressives and transtensives) which are very simple when compared with the more complex structures that occur in the area of the Central Domain that had been originated under a more plastic deformational regime due to the largest halite volume. The strike-slip faults usually originate complex structural effects in the geologic section of some basins which result in difficulty for the interpretation of seismic data. The complexities are related to the nature of the mechanism of the strike-slip faulting. The flow of salt along the strike-slip zones follows offsets upwards resulting in irregular folds when the salt thickness increases. Therefore, when the sequence that contains the salt layers is submitted to strike slip faulting, the geometry of the structures becomes normally complex. This could be explained due to the plastic behavior of the salt that acts as a layer where the strike-slip stresses are attenuated, hindering the faulting propagation in the upper sequences. In the Amazonas Basin is clear this relationship between the halotectonic features and Cenozoic strike-slip faulting. The seismic interpretations in this research are not enough to identify the structures related to the Quaternary events, but the geologic data and the information from focal solution mechanism of earthquakes and breakouts indicate that the Amazon Basin have remained active in the Quaternary time. Therefore, it is possible that halotecnonics have occurred during the Quaternary.Acesso AbertoTectônica salinaGeologia estruturalRio AmazonasDissertaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIASGEOLOGIA