Pollen in a perfect trap: the palynological record in Miocene gypsum

Abstract

Gypsum deposits formed during the middle Miocene Badenian Salinity Crisis (BSC) contain perfectly preserved palynomorphs with fossilised cytoplasms. The nature of the cytoplasm indicates that plasmolysis in a condensed brine solution took place prior to fossilisation. Two forms of plasmolysis are present: concave in zonoporate grains and convex in saccate, inaperturate, pantoporate and colporate specimens. The composition of the palynomorph assemblage is typical for the Miocene European lowland, with plants representing swamp, riparian, mesic and upland communities. Among the dominant taxa are: Pinus/Picea, Taxodium/Glyptostrobus, Ericaceae, Cathaya, Engelhardia and Quercus. The percentages of pollen grains with preserved content are very high for some taxa (Engelhardia, Ericaceae, Fagus, Liquidambar, Potamogeton, Quercus, Taxodium/Glyptostrobus and the Tricolporopollenites pseudocingulum group) and constitute a valuable indicator of the proximity of source vegetation to the depositional basin. Analysis of the pollens shows that, despite the salinity crisis, swamp/riparian and mesic plant communities surrounded the sedimentary basin and the climate remained humid.