INVESTIGADORES
DAVILA Federico Miguel
congresos y reuniones científicas
Título:
Influence of Peruvian flat-subduction dynamics on the evolution of the Amazon Basin
Autor/es:
EAKIN, C.M., LITHGOW-BERTELLONI, C., DÁVILA, F.M.
Reunión:
Congreso; AGU Meeting of the Americas; 2013
Resumen:
Despite the global prominence of flat or shallow subduction comparatively little is understood as to the dynamics of such systems and particularly how the overlying continent is affected. We can address this issue by modeling dynamic topography; deflections of the Earth?s surface due to the forces impinged by mantle flow, thus providing a crucial insight to the Earth?s interior by linking deep mantle processes to the surface. For this we choose the Peruvian flat-slab segment as our study area, the largest region of flat subduction currently in the world. The onset of the flat-slab system here is thought to have begun in the Mid-Miocene (~12Ma), around the same time as a major upheaval to the Amazon Basin took place, when drainage switched from the Caribbean Sea to the Atlantic Ocean as seen today. Computations of dynamic topography are highly sensitive to slab morphology, therefore in this study we create a realistic flat-slab model using hundreds of hypocentre locations from the NEIC earthquake catalog. Predictions of dynamic topography from this flat-slab model produce long wavelength dynamic subsidence, >1km in amplitude, and at well over 1000 km from the trench. This subsidence is located directly over the steeply dipping portion of the slab to the east, and is broadly matched by negative residual (non-isostatic) topography over the Amazon Basin. This dynamic low also remarkably coincides with 800m of sediment accumulation in the Sub-Acre/Solimões peri-cratonic basin of western Amazonia that cannot otherwise be explained by flexure from the Andean load, or by dynamic topography from a standard subduction model. Furthermore considering a transition from normal to flat subduction during the Mid-Miocene, our relative dynamic topography calculations suggest that the Andean foreland region would have been raised up whilst the Amazon Basin was dropped. Thus eastward fluvial transport would have been encouraged, leading to the formation of the Amazon River, one of world?s largest river systems, as we presently know it.