Preliminary results of the palynological investigation of the Toarcian deposits of Ionian Zone (Western Greece)

In this study we present preliminary palynological data from Lower Toarcian deposits of the Ionian Zone (Western Greece). The Ionian Zone belongs to the external Hellenides and during the Mesozoic constituted part of the southern Tethyan margin. The initially shallow carbonate platform of the Ionian Basin began to break up in the early Pliensbachian. The first deepening of the basin has been recorded in Siniais Limestones that are followed by Posidonia Beds. The occurrence of macroremains of the conifer Brachyphyllum nepos, together with geochemical and palynological studies of Toarcian deposits of the Ionian Zone, suggested the presence of a tropical biome in the broader area. The 20-m outcrop examined (Toka section) begins in the upper part of the Siniais Limestones and continues into the lower part of the overlying Posidonia Beds. In the studied deposits previous research has documented the local expression of the global Toarcian Oceanic Anoxic Event. The Early Toarcian Oceanic Anoxic Event has been associated with exceptionally high rates of organic-carbon burial, marine anoxia to euxinia, sea transgression, high palaeotemperatures and mass extinction and is generally considered as a significant climatic driven event. Palynological investigation of the deposits aims to contribute further to our knowledge about the Toarcian palaeoenvironmental conditions, while the resulting dataset is an additional contribution to the Jurassic biostratigraphy of the Ionian Zone. Most studied samples yielded a considerable amount of palynological residue, including moderate diverse and fairly well preserved palynomorph assemblages of pollen, spores and dinoflagellate cysts. Additionally in palynospectra from organic rich horizons a significant quantity of amorphous organic matter has been recorded.