Interpretação sísmica e modelagem gravimétrica 2D do Paleozoico inferior na porção Sudeste da Bacia do Parnaíba

• Autor(a) principal: Schuback, Victor Hugo Teixeira
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7039
• topic: Parnaíba Basin; Transbrazilian Lineament; Seismic Interpretation; Lower Paleozoic; Bacia do Parnaíba; Lineamento Transbrasiliano; Interpretação sísmica; Paleozoico Inferior; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA

We present a new perspective on the structural and stratigraphic framework in the southeast segment of the Parnaíba Basin. The interpretation of two-dimensional seismic reflection profiles over a lenght of 1500 km, associated to gravity data, revealed the presence of a grabenlike pre-silurian basin bounded by a major shear zone, trending NE-SW, denominated Transbrazilian Lineament (LTB). This research has built several isopach and basement maps that indicate the influence of the shearing zone LTB throughout the installation of the pré-silurian basin and the initial deposition of the silurian sequence of the Parnaíba Basin (Serra Grande Group). The pre-sillurian sequence mapped is bounded on the top by pré-silurian unconformity (PSU) and its base by the top of the basement, has a maximum thickness of 2400 meters, filling a 17km wide graben, bounded SE by a main fault that extends over 240km in NE-SW direction. Three main sequences were identified along the pré-silurian basin, sequences I, II and III. Due to its geological context and geographical position they were correlated with the Jaibaras Basin (BJ) unit, classified as a cambro-ordovician rift and located in the NE border of the Parnaíba Basin, parallel to LTB. The sequence I, more basal, has a thickness of approximately 200 m and has been interpreted as the pre-rift phase, correlated to the Ubajara Group (BJ). Above, Sequence II has maximum thickness of 1300 m on the central axis of the graben, interpreted as syn-rift I and correlated to Massape and Pacujá Formations of BJ. Finally at the top, Sequence III has a maximum thickness of 1200 meters and was interpreted as sin-rift II, correlated to the Aprazível Formation. The analysis of the aeropotential data and two dimensional gravity modeling processes along a seismic profile suggests a heterogeneous crystalline basement under pré-silurian and pos-silurian sequences, since the negative anomalies do not correlate directly with the total basin isopach map. The model that best fits to the bouguer gravity anomalie curve was the one that presented a high density intrusive body, located in the limit of superior/inferior crust in the LTB region. The main negative anomalie trends, long-shaped and direction N30E and N45E, were associated to low density meta-sedimentary blocks, possibly of Neorpoterozoic or older and found in structures alined to the LTB