TOver the last decade, the mechanisms behind the evolution of topography have been the subject for numerous pan-European projects, most remarkably under the umbrella of the TopoEurope ESF program and the spanish TopoIberia Consolider project. Despite these initiatives have considered the Iberian Peninsula as one of the key natural laboratories to address the problem, and despite they have resulted in a large volume of new data, the classical conundrums on the large-scale evolution of the topography of Iberia have beenseldom addressed via quantitative modeling methods. As a result, key questions on the timing and processes involved in building the Iberian topography remain open: What is the origin of the high mean elevation of the Peninsula, uncorresponded with its average cristal thickness? Was this topography created before or after the formation of large planation surfaces in many regions of Iberia? What are the relative quantitative contributions to topography induced by the peculiar microplate tectonics and the peculiar drainage evolution undergone by the Iberian Peninsula?
The aim of the present project is to address these questions by using: 1) numerical modelling of the present day 3D lithospheric structure of Iberia, in particular, the density distribution within the crust and upper mantle, based on potential field data (gravity and geoid). 2) numerical modeling of topographic evolution constrained from existing and new data of erosion rates, to determine the tectonic, transport, and climatic processes responsible for the Cenozoic evolution of the Iberian topography; 3) comparison with an extreme analogue to the Iberian basins that undergoes extreme uplift/erosion rates: the Zhada Basin (SW Tibet); and 4) punctual new data acquisition on erosion rates on both systems, quantifying Miocene/Quaternary river incision and erosion rates by dating the exposure to cosmogenic rays using the content in 10Be. The majority of the numerical models to be applied have been previously developed within the team. The results will fill temporal and spatial gaps in the the sparse data available for the Iberian basins and ranges and it will provide possible scenarios in which the observations are compatible with each other. More importantly, the results will test conceptual models for the evolution of topography in geological time scales, and will provide a quantitative understanding of the mechanisms responsible for the large-scale relief evolution, and for the present evolution of the surface topography of Iberia. Specific deliverables include an improved imaging of the crustal and lithospheric mantle structure in Iberia, a map of the tectonic velocity field in the Iberian Peninsula, and the spatial distribution of the recent surface erosion and drainage divide migrations between large drainage basins.
- Julien Babault (UAB)