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How Earth’s surface topography is affected by dynamics deep inside the mantle


IPGP - Îlot Cuvier


Séminaires de Sismologie

Salle 310

Alessandro Forte

GEOTOP - Université du Québec A Montreal

In this presentation I will explore the dynamics of the convecting mantle deep below the surface, as seen in the surface topography of our planet. Changes in dynamic topography due to this mantle flow contribute to the geological evolution of Earth's surface through processes of rock uplift, erosion, sedimentation, drainage changes, global bathymetry and sea level variations. Our ability to understand how the dynamics deep inside the Earth controls these surface processes has made rapid progress over the past decade. This has been achieved thanks to advances in seismic tomographic imaging of the 3-D structure in the Earth's interior and in the models that relate this structure to the process of thermal convection in the mantle. The most recent mantle flow simulations based on these tomography models now provide an improved understanding on how heat and mass is transported across the mantle, from the core-mantle boundary to the surface. These tomography-based convection models yield new insights on how the deep dynamics in the mantle is affecting the evolution of surface topography on our planet. They reveal, in particular, the crucial role of hot buoyant upwellings that originate from the lowermost mantle. These upwellings not only transport large amounts of heat (much greater than traditional hotspot estimates), they also contribute to large changes in dynamic topography.