Subduction, continental collision, and mantle dynamics in the Mediterranean - Tethyan realm: impact on oceanic circulation, climate, and the biosphere

Topography generated by subduction, mantle flow, volcanism, and continental collision in the Eastern Mediterranean – Tethyan realm enabled migration and diversification of terrestrial and marine faunas and facilitated Cenozoic (66 – 0 Ma) oceanographic and climatic changes. However, the topographic evolution of key regions and events such as closing the link between the Atlantic and Indo-Pacific Oceans through the Tethys Seaway, and the potential link between the Arctic Ocean and Paratethys Sea through the West Siberian Seaway, are still debated. Here, we review a series of published regional paleogeographic indicators including geological and biogeographic data and generate a new, continuous Cenozoic (i.e.,1 Myr time intervals) digital elevation model for the Tethyan realm. Recent paleoclimate modeling using a state-of-the-art Earth system model (the NorESM-F) show that related, and relatively small changes in paleogeography in these regions can cause large global ocean circulation changes. In particular, shallowing the Tethys Seaway facilitates a stronger overturning circulation in the Atlantic Ocean, while an open West Siberian Seaway may cause freshwater leakage from the Arctic Ocean; this weakens the overturning in the Atlantic Ocean if the Tethys Seaway is open. We further investigate the possible contribution of mantle convection to the evolution of this regional system using new, time-evolving dynamic topography models, and examine the consequences for mammal migration, ocean circulation, and climate. We show that paleotopographic changes in the West Siberian Seaway correlate with changes in dynamic topography. Our findings indicate a link between deep mantle convection, surface evolution, and climatic changes on geological timescales.