Rapid glacial isostatic uplift in Patagonia: Interplay of enhanced ice mass loss and slab window tectonics

R. DIETRICH; A. RICHTER; E. IVINS; H. LANGE; L. MENDOZA; L. SCHRÖDER; J. L. HORMAECHEA; G. CASASSA; E. MARDERWALD; M. FRITSCHE; R. PERDOMO; M. HORWATH

Rostock

Conferencia; 27 th International Polar Conference "Polar Systems under Pressure"; 2018

University of Rostock

Repeated geodetic GNSS observations at 43 sites distributed over the Southern Patagonian Icefield (SPI) region yield vertical uplift rates of up to 41 mm/a. These observations are used to validate two ?end member? ice load history scenarios that approximate unloading since the Little Ice Age (LIA) and to determine rheological parameters of a viscoelastic  earth model. The GPS observations link the ice loss to the soft  viscoelastic isostatic flow response over the time scale of the Little Ice Age (LIA), including ice loss in the period of observation. The  combination of SPI?s rapid melting and the unique regional slab-window tectonics that promotes a relatively low viscosity, is central to the interpretation of the observations. The preferred model and our observations point toward an effective upper mantle viscosity even lower than 1.6 1019 Pa s and a thin effective lithospheric thickness of 35 km.