Angiosperm fossils in supposed Jurassic volcanogenic shales, Antarctica

During palaeobotanical studies in the Antarctic Peninsula in February 1979, late Cretaceous or younger fossil angiosperm leaves were found within volcaniclastic rocks widely believed to be of late Jurassic age1. Although poorly preserved, these fossils are of great stratigraphical importance. They occur at Cape Alexandra, Adelaide Island (Fig. 1), in rocks correlated with the lowest part of the exposed succession (Sloman Glacier succession1). The fossils were found less than 10 km from the type locality for this succession at the head of Sloman Glacier (Fig. 1). However, towards the northern end of the island at Mount Bouvier (Fig. 1), ammonites and bivalves indicate that supposedly equivalent rocks1 are of Upper Jurassic age2. This intensive study of a very small part of the succession indicates that the volcanic history of Adelaide Island is much more complicated than was previously suggested by reconnaissance mapping

Paleogene palynostratigraphy of the eastern middle Magdalena Valley, Colombia

This work presents a detailed study of the pollen and spore distribution in the Paleocene-Eocene Lisama and La Paz Formations on the eastern border of the Middle Magdalena Valley, Colombia. One hundred and forty-seven samples obtained from cores and outcrops were prepared for palynological research, fifty-nine of which were rich in pollen and spores. Three hundred spore and pollen taxa were identified. The studied stratigraphic interval is a 2000 m thick coastal and fluvial deposit formed in a variable subsiding tectonic setting. The Lisama Formation is characterized by the dominance of the Proxapertites group. Some typical Paleocene forms start to disappear toward the upper part of the Lisama Formation (e.g.Bombacacidites annae, Ephedripites vanegensis, Retidiporites magdalenensis), and are followed by a barren interval probably linked to intense oxidation during paleosol development (the uppermost 266 m of the Lisama Formation). In the La Paz Formation there is a progressive appearance of early and middle Eocene species (e.g. Cyclusphaera scabrata, Foveotriporites hammenii, Monoporopollenites annulatus, Perfotricolpites digitatus, Spirosyncolpites spiralis, Striatopollis catatumbus, Bombacacidites gonzalezii). This biostratigraphic evidence indicates that an early-middle Eocene hiatus in the eastern area of the Middle Magdalena Valley basin is not present, as many authors have previously suggested. One new pollen genus, Foveomonoporites, and two new pollen species, Foveomonoporites variabilis and Psilamonocolpites operculatus are described and illustrated