Palynological characterization of a transgressive episode in transitional deposits in the Cretaceous Aren and Tremp formations (south-central Pyrenees, Spain)

Abstract

The overall marine regression leading to the infilling of the Cretaceous Pyrenean basin was punctuated by transgressive episodes. These events produced a complex architecture in the interfingering deposits in the marine Aren and continental Tremp formations in south-central Pyrenees. The Vicari section is useful for studying the lateral change between these marine-continental deposits bearing fossil vertebrates and pollen. In this section, palynological changes reveal in detail transgressive and regressive events in the lower part of the continental Tremp Formation, which could not be detected otherwise by non-correlated lithological changes. A rapid regression is documented through the contact between the lower Aren and Tremp deposits: in-situ dinosaur egg clutches and other vertebrate remains are preserved with terrestrial palynomorphs indicating warm humid palaeoclimatic conditions (tree ferns, cycads, etc.). Furthermore, palynological content, rich in marine phytoplankton, reveals a transgressive episode in the upper grey marls in the Tremp Formation.