MOUNTAIN UPLIFT, CLIMATE, DRAINAGES AND BIODIVERSITY IN THE ANDES-AMAZONIAN SYSTEM

The Cenozoic history of the Andes-Amazonian system was strongly influenced by plate tectonic processes such as the break-up of the Farallon Plate (into Nazca and Cocos plates), collision of the Panama Arch with the South American Plate, and subduction dynamics. During the Oligocene and early Miocene this resulted in uplift of the Eastern Cordillera, and in the middle Miocene closure of the Panama Isthmus. From about this time the Cordillera started acting as orographic barrier for Atlantic humid atmospheric masses. This situation led to major changes in the South American paleogeography, among which the onset of the transcontinental Amazon River, and is thought to have formed the basis for modern patterns of biodiversity in Andes and Amazonia. Parallel to this process, and at least from Eocene to late Miocene, large parts of western Amazonia were affected by estuarine conditions with varying degrees of salinity. In this paper I will discuss some aspects of our multidisciplinary research on a borehole in the Amazon submarine fan, providing key insights into the timing of onset of the Amazon River, and discuss different scenarios for the Plio-Pleistocene landscape in the Amazon drainage basin.

Sponsor: CLIM-AMAZON (www.clim-amazon.eu), a joint Brazilian-European facility for climate and geodynamic research on the Amazon River Basin sediment.