BIBLIOS

Tipo
Artigos em Conferência

Tipo de Documento
Resumo Extendido

Título
Morphotectonic analysis of the southern Portuguese Atlantic coastal zone – implications for active tectonics

Participantes na publicação
Figueiredo, P.M. (Author)
Rockwell, T.K. (Author)
Cabral, J. (Author)
Dep. Geologia
IDL
Ponte Lira, C. (Author)
Dep. Geologia
IDL

Resumo
The south Portugal is characterized by low tectonic rates (<0.3 mm/a), with infrequent large seismicity. Recent studies indicate a coastal region in southwest Portugal uplifting at higher rates (0.11 ± 0.01 mm/a) than the remaining southern portion of Portugal (~0.04 mm/a). The mechanisms responsible for the higher uplift are poorly understood, as well as the pattern of the increase in vertical motion and its exact location. In addition, some structures are associated with relevant morphology but their degree of Quaternary tectonic activity is also poorly constrained. Thus, with the purpose of investigating the regional Quaternary deformation and its patterns, as well as the difference in the uplift rate, 77 exorheic drainage basins along 460 km of the southern Portuguese coastline were analysed through the application of geomorphic indices. In this study we applied stream channel sinuosity S, basin relief ratio Rh, elongation Re, basin shape ratio Bs, valley height-width ratio Vf, basin asymmetry factor AF, hypsometry HI and, the stream-length gradient index SL, and we propose the terminal basin shape index TBS. Our aims are\\\\nmainly to (1) identify Quaternary deformation along presumed tectonic structures; (2) recognize uplift or subsidence along the\\\\ncoastline; and (3) test the application of geomorphic indices in low deformation rate environments. The cross-correlation of results led to the recognition of the São Teotónio-Aljezur-Sinceira fault system and the São Marcos-Quarteira Fault as major regional Quaternary faults, as well as to the interpretation of Quaternary activity for other structures. Spatial differences in uplift rates are identified through basin shape indices and valley height-width ratios, corroborating the recent studies. Altogether, results also demonstrate the applicability of some morphotectonic indices, even for low vertical motion rates.

Editor
C. Canora, F. Martín, E. Massana, R. Pérez y M. Ortuño


Instituição
Universidad de Alicante

Evento
Tercera reunión ibérica sobre fallas activas y paleosismología (Iberfault 2018 (Resúmenes), 11-13 junio de 2018, Alicante, España

Identificadores da Publicação
ISBN - 9788409024735

Local
Alicante, Espanha