An example of intraplate neotectonic activity, Vilariça Basin, northeast Portugal
1989; Wiley; Volume: 8; Issue: 2 Linguagem: Inglês
10.1029/tc008i002p00285
ISSN1944-9194
Autores Tópico(s)Geological and Geochemical Analysis
ResumoThe Vilariça tectonic basin (NW Iberian Peninsula) is presented as an example of intraplate neotectonic activity. The regional geological setting is first introduced then followed by a brief view on the neotectonic activity in Portugal. The basin consists of an elongated depression approximately 20 km long and 2 to 3 km wide, trending NNE–SSW. It is located astride a late Variscan strike‐slip fault (the Manteigas‐Bragança fault), suggesting that it might correspond to a structural depression related to reactivation movements on that fault, Mapping of Neogene and Quaternary cover deposits preserved in the basin and its vicinity was accomplished, and numerous evidence of tectonic deformation (tilting and faulting) affecting the sediments were found. Other geomorphological criteria are discussed, showing the structural origin of the Vilariça basin and its neotectonic activity. Attending to its location on the Manteigas‐Bragança fault, the Vilariça depression is interpreted as a "pull‐apart" basin resulting from left‐lateral strike‐slip displacement on that fault in the Quaternary. Average fault slip rates are estimated, with values comprised between 0.2 mm/yr and 0.5 mm/yr. These slip rates are typical of moderate to moderately high degrees of fault activity and are compatible with the regional faulting geomorphic expression and the relatively important historical and instrumental seismicity affecting the Vilariça region. Finally, a geodynamical model is proposed, and the studied area is presented in the geodynamic framework.
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