Author(s): Ressurreição, Ricardo ; Dias, Ruben Pereira ; Cabral, João ; Charifo, G.
Date: 2023
Persistent ID: http://hdl.handle.net/10400.9/4097
Origin: Repositório do LNEG
Subject(s): Bacia de Rio Maior; Pliocénico; Tectónica; Diapirismo; Rio Maior basin; Pliocene; Tectonics; Diapirism; Bacia de Rio Maior; Bacia de Rio Maior; Pliocénico; Pliocénico; Tectónica; Tectónica; Diapirismo; Diapirismo; Rio Maior basin; Rio Maior basin; Pliocene; Pliocene; Tectonics; Tectonics; Diapirism; Diapirism
SUMMARY: The Rio Maior basin is a NNW-SSE elongated tectonic basin, controlled by main faults with the same orientation. The basin was filled with sediments during the Pliocene, over Miocene deposits. Borehole data show a depocenter located near its eastern margin with the Pliocene sediments forming a dissymmetrical synform controlled by the NNW-SSE Cidral border fault. The sedimentation culminates in Pleistocene conglomeratic sandstones, apparently not deformed. During recent field work in a sand exploration quarry located in the SE extremity of the basin, a N-S fault affecting the Miocene and Pliocene was identified along ca. 400 m. Striated slickensides in the Miocene deposits indicate a predominant normal dip-slip component. This was interpreted as a prolongation or major ramification of the Cidral fault. Considering the proximity of extruded Jurassic evaporitic sediments at Fonte da Bica diapir, the extensional deformation in the Rio Maior area during the Pliocene is probably related with tectonic diapirism.
