BIBLIOS

Tipo
Artigos em Conferência

Tipo de Documento
Resumo Extendido

Título
Neotectonic activity of the Deixa-o-resto fault (coastal Alentejo, Portugal)

Participantes na publicação
Ressurreição, R. (Author)
Dias, R.P. (Author)
Cabral, J. (Author)
Dep. Geologia
IDL

Resumo
The Deixa-o-Resto fault is a main structure in the Mesozoic and Cenozoic tectonic evolution of the Alentejo littoral\nnorthern sector, having been reactivated during the Quaternary as a left lateral strike slip fault. The most relevant evidences of its neotectonic activity occur in the Deixa-o-Resto area, where there is morphological expression along a 4 km section, consisting in a linear scarp facing W with 40 m of maximum height. Here, a near vertical fault with reverse component affects Jurassic limestones and Pliocene sands, promoting the eastern block uplift. A 100 m vertical displacement of the Pliocene sediments was estimated based on outcrop and borehole data, which indicates a vertical slip rate of 0.02-0,03 mm/yr since the last 4.5-3 Ma. Onshore, the fault presents at least a 20 km extension between the Melides area and the Sines igneous intrusive massif, for which a Mw 6.9 and ≈37000-25000 years recurrence interval were obtained. On the offshore, a morphological lineament coincident with a mapped fault that extends to the descobridores seamounts is aligned with the inland recognized Deixa-o-Resto fault and is interpreted as\nits prolongation, giving a minimum length of 125 km as stated by previous studies. A maximum expectable earthquake of Mw 7.4 and recurrence interval of ≈104000-69000 years were estimated for the fault total extension. Since only the vertical component of displacement is known these slip rates are underestimated, giving longer return periods.

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


Instituição
Universidad de Alicante

Evento
Universidade de Alicante, Espanha

Identificadores da Publicação
ISBN - 9788409024735

Local
Alicante, Espanha