New didemnid ascidian spicule records calibrated to the nannofossil data chronostratigraphically in the Quaternary marine deposits of Lake Ä°znik (NW Turkey) and their paleoenvironmental interpretations

Based on the ascidian spicules and nannofossil records of the coring/drilled muds of Lake Ä°znik was marine, as an inlet or lagoon connected to the modern Gulf of Gemlik, during the Pleistocene to Upper Holocene. It was likely separated from the Marmara Sea and turned into a freshwater lake after the upper Holocene.