Paleoclimate in the Cenozoic time: Quantifying the role of North Atlantic plate tectonics and mantle processes

Abstract

In the Cenozoic time (66 – 0 Ma) the global climate changed from greenhouse to icehouse conditions. Changes in continents and ocean geometry, geography, and topography due to plate tectonics, erosion, and mantle dynamics played an important role in this complex transition. This thesis explores how the paleobathymetry of Northern Hemisphere oceanic gateways active during Cenozoic influenced the ocean circulation and climate variations. First, this study analyzes the distribution of oceanic sediments and the age of the oceanic lithosphere in the world’s oceans and derives analytical formulas to mathematically describe sedimentation trends in the major oceanic basins. Second, this methodology is implemented in a new global paleogeography model, including detailed reconstructions of the Northern Hemisphere oceanic gateways, ultimately providing a set of realistic global paleogeographic reconstructions for the Cenozoic time. Third, the climatic influence of oceanic gateway geometry at the Eocene-Oligocene Transition (ca. 34 Ma) is modelled using the Norwegian Earth System Model. These simulations show that the climate is highly sensitive to the evolution of the Atlantic – Arctic oceanic gateways.