Stable isotope composition of the Miocene Dinaride Lake System deduced from its endemic mollusc fauna

摘要: The aragonite shells of 55 mollusc specimens from the late Early and early Middle Miocene two palaeolakes Dinaride Lake System (DLS) are analysed for their δ18O δ13C signatures. data set has a bimodal distribution with prominent peak between −3 −4‰ both isotopes second much weaker at more depleted values c. −9 to −7‰. Taxa ‘heavy’ interpreted represent inhabitants shores or shallow areas lake. Depleted attributed species preferring freshwater habitats springs small rivulets, thus representing end-member. overall rather high in stable result combination evaporation effects influx already isotopically heavy karstic catchment area. Thus, DLS is as closed system without marine influence but enough contribution keep oxygen close −5‰. Mean lake surface water temperatures, based on δ18Oshell values, excluding end-member taxa, range around roughly 19–21°C. Despite problems calculating these agreement mean annual air temperatures deduced palaeobotanic record by applying Coexistence Approach method. seasonal was 10–11°C mainly recorded settings. signatures lack this due temperature regime less fluctuating dissolved inorganic carbon (DIC) pool. Congeneric same stratigraphic horizon often display discrete different isotope This fact suggests habitat segregation might be major factor sympatric speciation endemic radiation within fauna DLS.