Geodynamics of the Central Alpine Mediterranean Orogenic System: Mantle characterization and vertical motions
The Alpine Mediterranean Orogenic System encompasses a set of tectonic domains linked to the closure of the Tethyan Ocean during the Late Cretaceous-Cenozoic, characterized by an enigmatic alternation of fold-and-thrust belts separated by oceanic domains. This alternation and the closure of the Tethys itself are the consequence of the onset of counter-clockwise rotation and northward motion of the Nubia plate against Eurasia that initiated multiple subductions of the Tethyan oceanic realms around 83.5 Ma. Lateral changes in the subduction polarity in the Central Mediterranean region gave rise to three orogenic belts (Apennines, Dinarides and Carpathians) separated by two extensional back-arc basins (Tyrrhenian and Pannonian) and the Adriatic microplate. This complex segmented subduction system and the corresponding roll-back of the individual slabs generated an active return mantle flow with mantle-sourced volcanism, thrust-belts and deep depocentres. However, despite the large amount of scientific literature about the age, geometry, size and location of these oceanic domains, the underlaying geodynamic mechanisms as well as the interconnections between the resulting orogenic belt/back-arc basins remain under discussion. In this project we aim to bring new light on how the Central Alpine Mediterranean Orogenic System has been shaped by the Africa-Eurasia convergence and on the triggering mechanisms that accommodated this convergence. We also aim at clarifying the impact of these events on the surface mass redistribution and the conditions under which the Tyrrhenian, Adriatic and Pannonian sedimentary basins (main repositories of natural resources in the region). For this we will perform numerical modeling on a transect crossing the Central Mediterranean through the Tyrrhenian back-arc oceanic basin, the Apennines fold belt, the doubly subducting Adriatic Sea, the Dinarides fold belt, the Pannonian back-arc continental basin and the Carpathians fold belt to the SW of the stable Eurasia plate. Our methods combine geophysical, structural and petrological data to infer the crustal and upper mantle structure down to 400 km depth. We will apply both static (present-day) lithospheric structure and geodynamic modelling to account for mantle seismic velocities, surface heat flow measurements, elevation, gravity and geoid anomalies, and sedimentation/erosion data. We will obtain a new balanced geological cross-section of the lithosphere consistent with plate reconstructions and geophysical data.
- Ana Negredo, Universidad Complutense de Madrid
- Jeroen van Hunen, Durham University