The Eocene-Oligocene climate transition (EOCT) was a period of rapid global cooling at abou 34 Ma ago, representing a major step from early Cenozoic greenhouse toward modern icehouse conditions. It was accompanied by a series of dramatic changes in Earth’s environmental system, including an expansion of ice sheets on the Antarctic continent, a global sea-level drop, a declining atmospheric CO₂ concentration, a deepening of the calcite compensation depth, and a biotic reorganization, thus has great significance in understanding the mechanisms behind the long-term Cenozoic cooling, the behavior of regional climate in response to rapid cooling and the effects of major climatic changes on the biotic reorganization.