NEW STRATIGRAPHIC DATA CONCERNING THE MAR INE OLIGOMIOCENE FORMATIONSOF THE SIVAS BASIN (TURKEY)

The stratigraphy of the marine Oligo-Miocene formations of the Sivas b asin has been revised on the basis of planktic and benthic fauna and m icrofauna. In the Sivas area, three of the main structural units prese nt three distinct sequences which correspond to three paleoenvironment s: basinal open marine, coral platform and, lagoon at the margin of em ergent areas. The Oligocene age of the massive gypsum is confirmed. Du e to the presence of continental sequences of the same age to the west and to the south of Sivas, the direct connection with the Eastern Med iterranean appears move difficult to interpret.