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

Abstract

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.

Weathering study of the gneissic rock mass from the Monte Seco tunnel region, southeastern Brazil.

“…Some of the NE-to ENE-trending normal faults of southeastern Brazil, recognized by Riccomini et al (1989) and Riccomini and Assumpção (1999), are associated with a distensional tectonic event whose minor tensile axis is oriented along the NW-SE quadrant. The normal faults in the weathered basement rock, as observed by Calegari et al (2016), and in the superficial deposits, as observed by Mello et al (2005) and Hatushika et al (2005), were related to this stress state, in accordance with the orientation of F1 fractures in the Monte Seco region.…”

“…This was accompanied by the intrusion of small-scale dike swarms dated to 136 Ma. The Monte Alegre alignment (AFZ) fracture set, whose genesis is connected to the Colatina Lineament located S of Vitória (capital of the state of Espírito Santo), shows features that indicate assimilation of the tectonic movements, reactivating some of these structure planes as NNW-SSE normal faults (Calegari et al 2016 (Hasui 1990). Some of the NE-to ENE-trending normal faults of southeastern Brazil, recognized by Riccomini et al (1989) and Riccomini and Assumpção (1999), are associated with a distensional tectonic event whose minor tensile axis is oriented along the NW-SE quadrant.…”

Multisource data integration for groundwater prospecting in Precambrian shear zones, Espírito Santo State (Southeastern Brazil)

“…In the Espírito Santo State, Ribeiro (2010) and Hartwig and Bozzi (2019) recognized three brittle deformation phases responsible for landform development and deformation of the semi-consolidated sediments of the Barreiras Formation (Miocene). Calegari et al, (2016) recognized a NWtrending Lineament in the Espírito Santo southeastern margin, named as the Alegre Fracture Zone, originated in the Cambrian Period and reactivated in the Cenozoic Era. Lourenço et al (2016) obtained similar results for the Piúma lineament, a 70 km long and N50W-trending brittle shear zone.…”

Compartimentação morfoestrutural da Bacia Hidrográfica do Rio Itapemirim, sul do estado do Espírito Santo

“…Outra estrutura geológica observada regionalmente é o Lineamento Alegre (Calegari et al, 2016), de direção NNW-SSE, subparalelo ao Lineamento Colatina (Belém, 2014), este presente no norte do estado. O Lineamento Alegre atravessa todo o sul capixaba e penetra na Bacia de Campos, onde controla altos e baixos estruturais (Calegari et al, 2016); porém, na área continental estudada, não delimita compartimentos morfoestruturais. Destaca-se, por outro lado, o Lineamento Piúma (Féboli, 1993) e estruturas associadas, que compõem um trend de direção NW-SE que delimita altos estruturais na BHRI.…”

“…Alguns desses lineamentos se estendem ao longo de toda a área, atravessando mais de um compartimento. Um exemplo é o Lineamento Alegre (Calegari et al, 2016), que atravessa o Complexo Intrusivo Santa Angélica, próximo a Jerônimo Monteiro, controlando escarpas alinhadas e incisão de vales (Figura 8D). Outros lineamentos de abrangência regional delimitam compartimentos, separando-os por meio de escarpas alinhadas nas direções NE-SW e NW-SE Figura 7.…”