SHOALING OF THE CENTRAL AMERICAN SEAWAY : SIMULATING CLIMATE AND EPSILON-NEODYMIUM RESPONSE (Invited Presentation)

The Central American Seaway played a pivotal role in shaping global climate through the Cenozoic. Recent geological surveys have provided new constraints on the timing of its uplift, suggesting the CAS shoaled far earlier than previously thought. Also increasing epsilon-Neodymium (ε_Nd) information measured on fossil teeth and debris from the Caribbean and tropical Pacific help hypothesize the history of water masses. Here we present the first fully coupled climate simulations that include the ε_Nd transport and investigate the timing and oceanic impact of the Central American Seaway shoaling and closure. We show that a narrow strait is sufficient to affect inter-oceanic circulation and leads to a sluggish ocean meridional transport in the Atlantic. We suggest that a threshold between 200 and 500 meters determines the depth at which the sill dramatically impact the global ocean circulation. Despite limitations linked to model resolution, our results confirm and sharpen earlier interpretation of water masses flows through the seaway. Simulated ε_Nd values in the Caribbean show that inputs from radiogenic Pacific intermediate waters in the Caribbean decrease when the seaway shoals. Compared to published data, they provide a first insight to constrain the Panamanian seaway uplift, and suggest a shoaling above 200 meters around 9 Ma at the latest.