Palaeoenvironment of the Sarmatian-Pannonian boundary in the Vienna Basin

Ostracods and foraminifers are often used as proxies to reconstruct paleoenvironments and their changes through time. In this study, they are utilized to give insights on the environmental transitions at the Sarmatian-Pannonian-boundary of the Vienna Basin at which various layers of accumulated ascidian spiculae were previously observed.
A drill core was taken during the expansion of the subway network in Vienna. It originates from the depth range of 38-42 meters below surface which is suggested to represent the transition from the Sarmatian to the Pannonian stages at this location. Selected 5cm segments were extracted from the core and processed. The preparation included wet sieving with 125 and 250µm mesh size. After oven-drying, the remaining sediment was split, and the microfossils were picked. Ostracods and foraminifers were identified using literature and paleoenvironmental changes were inferred based on variations in their assemblages along the core.
Preliminary results reveal distinct patterns in the assemblages of ostracods and foraminifers. At 42m below surface no ostracods and very few foraminifers are present indicating high sedimentation rates. At 40,5m below surface the identified ostracods species belong to Loxoconchidae and Leptocytheridae families and foraminifers belong to the families Elphidiidae and Miliolidae. At 38m below surface no foraminifers are present, and the ostracods belong to Candonidae families which are associated with lacustrine waters.