Formações jurássicas da região de Albufeira: estratigrafia, consequências cartográficas e tectónicas

Abstract

Key-words: Upper Jurassic - Ammonoids - Central Algarve - Geologic mapping - Tectonics. The geological survey of Albufeira map area envolved the execution of several logs· on Jurassic formations. The study of amonoid forms allowed the interpretation and the establishement of correlations on the Upper Jurassic· series and the definition· of the regional stratigraphic sequence. Based on this fauna, recalled for the fust time in this region, the marly and marly-limestone units of the lower part. of the series are placed in the interval from middle Oxfordian (Plicatilis? - Transversarium zone) to Kimmeridgian (Hypselocyclum zone). Albufeira village is in part built on these fonnations. The overlaying dolomitic limestones with heterochronous limits at basin level are dated Kimmeridgian. The Jurassic series finishes with compact sub-lithographic limestone beds containing fossils of corais, gastropods and echinoid radioles of Kimmeridgian-Portlandian age. The geological map is presented and the regional structure is discussed. .