Publicação

Tertiary and Quaternary north of the Douro river (Portugal): the geologic record and the geomorphologic setting

Ver documento

Detalhes bibliográficos
Resumo:In northernmost area of Portugal the Tertiary and Quaternary record occurs on two different morphotectonic settings: (1) the eastern area (Trás-os-Montes region) and (2) the western, next Atlantic margin (Minho region). Sedimentology and geomorphology allowed mapping of the drainage changes and a description of the depositional systems. The sedimentological information includes lithofacies description and analytical results (texture, grain size, clast analysis, heavy and 2µm mineral associations). Based on these studies four main cycles were distinguished. In the eastern area the sedimentary record comprises the Paleogene and the Miocene. The Paleogene cycle represents an alluvial fans system kept in strike-slip basins. In the Miocene cycle are recognised two Tectonic Sedimentary Units, both recording the proximal facies of a braided fluvial system. This endorheic system was draining to the Douro Basin (Spain). The Atlantic capture of the drainage promotes glyptogenesis and the sedimentary record became scarce. In the western area, near the Atlantic Ocean, the sedimentary record is geographic and stratigraphic limited (Late Pliocene and Quaternary). In this area sedimentation is related to exorheic drainage, formerly stored in depressions. During the Quaternary cycle, fluvial terraces are generated. Consequently are defined four main sedimentary cycles, during Paleogene, Miocene, Late Pliocene and Quaternary. The tectonic activity controlled sedimentation and preservation of the older sedimentary record in eastern area. Lesser tectonic activity and greater glyptogenesis/sedimentogenesis ratio justified the narrow and newer record in western area.
Autores principais:Alves, M. I. Caetano
Outros Autores:Pereira, D. I.
Assunto:Geology and landscape Portugal N Fluvial sediments Tertiary and Quaternary Ciências Naturais::Ciências da Terra e do Ambiente
Ano:2000
País:Portugal
Tipo de documento:outro
Tipo de acesso:acesso aberto
Instituição associada:Universidade do Minho
Idioma:inglês
Origem:RepositóriUM - Universidade do Minho

Registos relacionados

Registos relacionados