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Advisor(s)
Abstract(s)
A área em estudo situa-se no litoral estremenho e revela indícios de modificações na organização da rede de
drenagem durante o Quaternário. Após a caracterização sumária das características lito-estruturais do sector
terminal da bacia do Rio Alcabrichel, põe-se em evidência, através das formas de relevo e dos sedimentos
correlativos, um paleoleito alcandorado do Rio Alcabrichel. Dado que os testemunhos geomorfológicos são
implicando o rejogo do diapiro de Maceira.
Low Alcabrichel River basin drainage network evolution (Lourinhã). The paper presents a study of a drainage system organization in Estremadura coast (north of Lisbon, Portugal), which was deeply modified during the Quaternary. The distal sector of Alcabrichel River basin cuts the Jurassic and Cretacic carbonated and detritic rocks, cover by scarce quaternary deposits. A diapiric structure gives place to a complex structural arrangement. The morphology exhibit scarp faults, dissymmetric valleys in monocline structure as well as an anticline valley and gorges cut in Jurassic limestones. Besides this structural conditioning, the presence of a palaeoriverbed of Alcabrichel River, in a high position in relation to the current alluvial plain, has an important palaeo-environmental meaning. This palaeovalley is related to a completely different drainage organization. Nowadays to reach the sea the river cuts two gorges in compact limestone, while the inherited streambed, still preserved at 60m high, develops in friable sandstone. To explain the re-organisation of the drainage system the authors discuss evidences of neotectonic activity and propose two different geomorphological evolutions.
Low Alcabrichel River basin drainage network evolution (Lourinhã). The paper presents a study of a drainage system organization in Estremadura coast (north of Lisbon, Portugal), which was deeply modified during the Quaternary. The distal sector of Alcabrichel River basin cuts the Jurassic and Cretacic carbonated and detritic rocks, cover by scarce quaternary deposits. A diapiric structure gives place to a complex structural arrangement. The morphology exhibit scarp faults, dissymmetric valleys in monocline structure as well as an anticline valley and gorges cut in Jurassic limestones. Besides this structural conditioning, the presence of a palaeoriverbed of Alcabrichel River, in a high position in relation to the current alluvial plain, has an important palaeo-environmental meaning. This palaeovalley is related to a completely different drainage organization. Nowadays to reach the sea the river cuts two gorges in compact limestone, while the inherited streambed, still preserved at 60m high, develops in friable sandstone. To explain the re-organisation of the drainage system the authors discuss evidences of neotectonic activity and propose two different geomorphological evolutions.
Description
Keywords
Paleovale Rio Alcabrichel Neotectónica Diapirismo Paleoriverbed Alcabrichel river Neotectonic Diapirism
Citation
Publisher
Associação Portuguesa de Geomorfólogos