The Alegre Lineament and its role over the tectonic evolution of the Campos Basin and adjacent continental margin, Southeastern Brazil

• Published in: Journal of South American earth sciences Vol. 69; pp. 226 - 242
• Main Authors: Calegari, Salomão Silva, Neves, Mirna Aparecida, Guadagnin, Felipe, França, George Sand, Vincentelli, Maria Gabriela Castillo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-08-2016
• Subjects: Alegre Lineament; Brittle structures; Reactivation; Alegre Lineament; Brittle structures; Reactivation
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2016.04.005

The structural framework and tectonic evolution of the sedimentary basins along the eastern margin of the South American continent are closely associated with the tectonic framework and crustal heterogeneities inherited from the Precambrian basement. However, the role of NW-SE and NNW-SSE structures observed at the outcropping basement in Southeastern Brazil and its impact over the development of those basins have not been closely investigated. In the continental region adjacent to the Campos Basin, we described a geological feature with NNW-SSE orientation, named in this paper as the Alegre Fracture Zone (AFZ), which is observed in the onshore basement and can be projected to the offshore basin. The main goal of this work was to study this structural lineament and its influence on the tectonic evolution of the central portion of the Campos Basin and adjacent mainland. The onshore area was investigated through remote sensing data joint with field observations, and the offshore area was studied through the interpretation of 2-D seismic data calibrated by geophysical well logs. We concluded that the AFZ occurs in both onshore and offshore as a brittle deformation zone formed by multiple sets of fractures that originated in the Cambrian and were reactivated mainly as normal faults during the rift phase and in the Cenozoic. In the Campos Basin, the AFZ delimitates the western side of the Corvina-Parati Low, composing a complex fault system with the NE-SW faults and the NW-SE transfer faults.
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•The Alegre Lineament is a regional fracture zone of SE Brazil that originated in Cambrian.•The Alegre Frature Zone was reactivated as normal faults in the rift phase and Cenozoic.•The Alegre Frature Zone control an important depocenter in the Campos Basin.