Preliminary global paleogeographic maps through the Greenhouse-Icehouse transition: forcing of the Drake Passage and Asian Monsoons.

International audiencePaleogeographic maps are essential for understanding Earth dynamics. They provide the necessary boundaryconditions for climate and geodynamic modeling, surface processes and biotic interactions. In particular, theopening and closing of ocean gateways and the growth of major mountain belts are major drivers of climatechanges and biotic interchange. However, the timing and spatial extent of such events are highly controversial andregularly questioned by new data. As part of the ERC “MAGIC” project focusing on Asian Monsoons during theIcehouse to Greenhouse transition we thus produced a set of worldwide Cenozoic paleogeographic maps in theperiod time between 60 to 20 Ma, with a set of boundary conditions specific to the India-Asia collision zone andthe Drake Passage.The creation of a paleogeographic map followed a rigorous and reproductively methodology that integrates paleo-bathymetric, paleoshoreline and paleotopographic data into a coherent plate tectonic model using the open sourcesoftware GPlates. (1) We use the model provided by Seton et al. (2012) as a first order tectonic model modifiedto integrate the full restoration of five regions: the Andes, the Scotia Arc, Africa, The Mediterranean Sea and theTibet-Himalayan collision zone. (2) The paleobathymetry was provided by Müller et al. (2008) using age-depthrelationships and assuming symmetric ridge spreading. (3) Paleoshoreline maps were modified according to thefossil database from fossilworks.org and the geological record and were used to represent the boundary betweenterrestrial and marine paleo-environments. (4) To reconstruct paleoelevations, the most controversial task, wecompiled a wide range of data including stable isotope, leaf physiognomy, and thermochronology combined withregional fossil and geological records (tectonic setting) and geomorphological data. Finally, we use the opensource GMT software and a set of masks to modify the current Earth relief model (ETOPO) according to theestimated paleoelevation for specific region at each period of time.Our approach specifically takes into account the evolution of continental margins. Paleotopographic evolution iscoupled with the evolving shape of continents. Considering the constant addition of new data and models, thevalue of this method is to generate a progressive paleorelief model of the Earth that can be easily compared andupdated with new data