Contribuições para o estudo estratigráfico e paleobotânico dos "Grés grosseiros inferiores" (arenitos do Carrascal). I - A jazida de Almas do Juncal

Abstract

Key-words: Spores - Pollens - Plant macroremains - Grés Grosseiros Inferiores - Aptian - Albian - Montemor-o-VelhoPortugal. This paper reports the results of the palynological and of the plant macroremains studies from a silt-clay levei belonging to the member b of the .Grés Grosseiros Inferiores» Formation at Almas do Juncal (Monternor-o-Velho). The pollen and spore association is quite similar to that of the .Grés de Almargem superiores». It is characterized by the abundance of Ischyosporites teixeirae PAIS & REYRE, Patellasporites tavaredensis GROOT & GROOT, severa! speciesof Cicatricosisporites of Appendicisporites and Cyathidites. The variety and constancy of those forms and the presence of rare Esquisetosporites virginiaensis and Ephedripites sp. suggest an age not previous to Aptian. The scarcity of primitive angiosperm pollens (Stellatopollis sp.) as well as the absence of tricolpate, tricolporate and/or triporate pollens indicates an age not younger than low Albian. From the rnacroremains are withstanding: Pseudocycas tenuisectus (SAPORTA) FLORIN, Brachyphyllum obesum HEER, Frenelopsis sp., o Sequoia sp., cf. Acaciaephyllum sp., Proteaephyllum sp. and Rogersia angustifolia (FONTAINE). This association has c1ear analogy to those of the inferior zones of the c1assic deposits of Potornac (Aptian?); those from Buarcos deposits (Aptian ?), Tavarede and Grada in the .Grés Grosseiros Inferiores» as well as with the associations of .Grés de Torres Vedras», from Serra d'El Rei, frorn Belas and Runa dated Aptian-Albian.' ln conclusion, the deposits of Almas do Juncal are more recent than those of Buarcos and rnay be correlated to the ones from .Grés de Almargem superiores» (upper Aptian).