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Tectonic and neotectonic implications of a new basement map of the Lower Tagus Valley, Portugal
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Advisor(s)
Abstract(s)
In this paper we present a new basement (defined here as Paleozoic, Precambrian and Mesozoic igneous rocks) map of the Lower Tagus Valley area. This map
is a contribution to the understanding of the structural evolution of the top of the basement in the Lower Tagus Valley area during the Mesozoic and Cenozoic
Eras. The map was produced using aeromagnetic, well, seismic reflection and geological outcrop data. It shows unprecedented details of the geometry of the
basement rock's surface with higher resolution and covers a larger area than the previous basement map of the study area. In spite of an estimated average
error of 200 m in depth and an horizontal resolution of 4 km, our map not only reproduces with accuracy several well known basement structures but it also
emphasizes previously unknown features. Major basement faults were inferred from large depth variations at the top of the basement, magnetic 2D Euler
deconvolution and horizontal gradient analysis and are compatible with surface geological structures, well data and hydrogeological information. Implications
to the geodynamic evolution of the SW European Variscides and consequences to Meso-Cenozoic tectonics are discussed. The correlation of the basement
structures with instrumental seismicity is carried out and their neotectonic activity is discussed on the basis of existing geological outcrop data.
Description
Keywords
Tectónica Neotectónica Sismicidade Reflexão sísmica Vale do Rio Tejo (Portugal) Baixo Tejo (Portugal)
Citation
Carvalho, João... [et al.] - Tectonic and neotectonic implications of a new basement map of the Lower Tagus Valley, Portugal. In: Tectonophysics, 617 (17 March 2014), p. 88-100