MITE
Modelling the Iberian Topographic Evolution
Duration: 2015 - 2018
Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia
KEYWORDS: large-scale tectonics, erosion, sedimentary basins, drainage network, lithosphere structure, potential fields
Introducción para público general:
El relieve de Iberia es poco común. Pese a su importante elevación media de 660 metros sobre el nivel del mar, la mayor parte esta microplaca tectónica ha sufrido poca deformación durante los últimos 30 millones de años. Esto supone un problema geológico porque las regiones con una tectónica de placas poco activa tienden a ser erosionadas a lo largo del tiempo geológico y a quedar allanadas al nivel del mar. En este proyecto hemos explorado dos mecanismos que intentan explicar esta peculiar evolución de Iberia. Por un lado, estudiamos la transmisión de deformación desde los límites activos hacia el interior de forma que imponga un engrosamiento de la corteza terrestre y su levantamiento. Y por otro lado, hemos investigado la formación de grandes cuencas lacustres durante el Neógeno y su papel atrapando las rocas transportadas e impidiendo la erosión efectiva del interior de la península. Nuestros resultados sugieren que la colmatación de estas cuencas hace unos 10 millones de años produjo su desbordamiento y la formación de nuevas redes fluviales con gran capacidad para erosionar la superficie como el Duero, el Ebro y el Tajo pero que aún no han tenido tiempo para reducir de forma significativa la topografía heredada de la anterior etapa.
Spain is the 5th highest country in Europe. Mean elevation of countries in Europe (darker countries are higher).
Technical introduction:
Over the last decade, the mechanisms behind the evolution of topography have been the subject for numerous pan-European projects, most notably 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 been seldom 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 crustal 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 analogue system to the Iberian basins that undergoes extreme uplift/erosion rates: the Zhada Basin (SW Tibet);
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 results will fill temporal and spatial gaps in 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. Specific deliverables include an improved imaging of the crustal and lithospheric mantle structure in Iberia, a map of the model-derived tectonic velocity field in the Iberian Peninsula, and the spatial distribution of the recent surface erosion and drainage divide migrations between large drainage basins. 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.
Main involved researchers:
Dr. Daniel Garcia-Castellanos (PI) (ICTJA-CSIC)
Dr. Ivone Jimenez-Munt (PI) (ICTJA-CSIC)
Prof. Manel Fernandez (ICTJA-CSIC)
Prof. Jaume vergés (ICTJA-CSIC)
Dr. Loreto Anton (UNED)
Dr. Javier Fullea (iGEO)
3D print of the relieve and crustal thickness of Iberia.