| Summary: | The Glacial Isostatic Adjustment (GIA) process describes the response of the Earth's surface to variations in land ice cover. Models of the phenomenon, which is dominated by the influence of the Late Pleistocene cycle of glaciation and deglaciation, depend on two fundamental inputs: a history of ice-sheet loading and a model of the radial variation of mantle viscosity. Various geophysical observables enable us to test and refine these models. In this work, the impact of the GIA process on the rotational state of the planet will be analyzed, and new estimates of the long-term secular trend associated with the GIA process will be provided. It will be demonstrated that it has undertaken a significant change since the mid-1990s. Other important observables include the vast amount of geological inferences of past sea level change that exist for all the main coasts of the world. The U.S. Atlantic coast is a region of particular interest in this regard, due to the fact that data from the length of this coast provides a transect of the forebulge associated with the former Laurentide ice sheet. High-quality relative sea level histories from this region will be employed to generate a new model of the GIA process that includes for the first time data from the forebulge region in its optimization process (the ICE-6G_C (VM6) model). Then, the series of analyses is extended to include space-geodetic observations of present-day vertical uplift of the crust. A solution reconciling all available data from the continent, named ICE-7G_NA (VM7), is obtained through modest further modifications of both the viscosity structure of the model and the North American component of the surface mass loading history. It provides an excellent fit to the constraining data related to the GIA process, including observations of the time-dependent de-levelling of the Great Lakes region. Finally, to test the global exportability of the new model, its predictions of relative sea level change are tested against observations from the Western Mediterranean region. Ph.D.
|
|---|