Abstract
The continental sea that used to extend from the Mediterranean to China, here referred to as the Eurasian Sea, fluctuated across Eurasia during the warm Paleogene times before its major retreat at the Eocene-Oligocene Transition (EOT) leaving behind the landlocked Paratethys sea. The drivers of the Eurasian sea evolution and its role on Eurasian ecosystems remain poorly understood. This lack of understanding is in large part due to the too fragmentary information currently available on Central Asian sedimentary marine and continental records, in particular in Kazakhstan where existing records remains very poorly dated and correlated. We report new chronostratigraphic data from key sedimentary marine and continental records from westernmost to easternmost Kazakhstan covering the period from the Middle Eocene Climate Optimum when the Eurasian sea reached its largest extent, until its final retreat at the Eocene-Oligocene Transition. These are combined with a compilation of paleoclimate proxies, depositional environments including palaeontological assemblages in a regional stratigraphic framework encompassing the region from the Caspian Sea to Eastern China. Initial results compared to numerical climate simulations enable to discuss potential links between sea fluctuations and geodynamic drivers, climate events, carbon sinks, basin to ocean connections, biome distributions and faunal dispersal routes.