Lower Cretaceous Pollen–Spore and Mesofossil Associations of the Bombarral Formation (Lusitanian Basin, Western Portugal)

Abstract

The Lower Cretaceous of the Lusitanian Basin (western Portugal) contains rich assemblages of plant remains. The study of the palynological and mesofossil flora of the Berriasian Bombarral Formation in Vale Painho, near Juncal, contributes to ascertaining the environmental conditions during deposition, the vegetation diversity, and the unit’s age. The fossil site is just below the base of the Figueira da Foz Formation, a basin-wide breakup paraconformity. Regional correlation with biostratigraphically dated units (Lourinhã p.p., Farta Pão, Porto da Calada, and Serreira) points to a Berriasian age for the top of the Bombarral Formation. The Vale Painho palynological assemblage is clearly dominated by fern spores and gymnosperm pollen. The mesofossil flora is characterized by seeds of conifers or taxa related to the Bennettitales– Erdtmanithecales–Gnetales (BEG) group, in agreement with palynomorphs. No angiosperm remains were recognized. The assemblage is very similar to the Berriasian to Valanginian Bornholm flora (Denmark). Plant features and sedimentary proxies indicate a hot climate with marked seasonality in precipitation.KeywordsBombarral FormationLower CretaceousBerriasianMesofossilsPalynomorphsPortugal