Evolução paleogeográfica e paleobiogeográfica do Caloviano-Kimeridgiano do Algarve

Abstract

Key-words: Paleogeography - Paleobiogeography - Callovian - Oxfordian - Kimmeridgien - Algarve. The littoral and the «barrocal» of the Algarve correspond in part to a meso-cenozoic sedimentary basin with a deeping south monocline structure,cut by North-Souch faults and by two East-West longitudinal flexures. The lithostratigraphic and chronosrratigraphic study of the Jurassic formations, undertaken during the last years, allow a better knowledge of the paleogeographic and paleobiogeographic evolution of these formations and particularly of the Callovian-Kimmeridgian. Lower Callovian facies , being similar from Sagres in the West to beyond Tavira, show the uniformiry of the sedimentary conditions. Since Middle Callovian, the beginning of the regressive cycle is responsible for a major unconformiry between Dogger'and Malm. During the Lower Oxfordian a new sedimentary cycle begins with a transgression afecting the region south of the Albufeira-São Brás de Alporcel-Tavira line thus originating a gulf centered in che Loulé area which rapidly diminishes since the Lower Kimmeridgian. The faunistic affinities are always tipically cethyan although some classic boreal fauna exist, in contrast wich the Norchern Tagus basin (where affinities are sub-boreal during the Callovian).