CLOSURE OF THE PANAMA SEAWAY AND ITS PALEOCEANOGRAPHIC AND PALEOCLIMATIC EFFECTS

Panama Seaway located at Central American region was once an important seaway connecting the equatorial Pacific and Atlantic. Its gradual closure caused by tectonic movements from the middle Miocene to Pliocene has been thought to significantly influence the ocean and climate. On one hand, its closure pro-gressively cut off direct seawater exchange between the equatorial Pacific and Caribbean Sea. Disruption of tropical seawater connection between the Pacific and Atlantic through the seaway led to significant diver-gence in physical properties of seawater, such as salinity and nutrients, as well as large reorganization of circulation patterns in these two ocean basins. On the other hand, reorganization of circulation induced by the closure probably played an important role in climate change in the late Cenozoic, especially in initiating Northern Hemisphere Glaciation through a set of feedbacks which are still under exploring. This paper briefly summarized research progress in the past few decades on closure process of the Panama Seaway and its impacts on the ocean and climate. Some relevant problems which remain controversial and need more studies are also discussed in the paper.