Investigation of the roll-back subduction of narrow oceanic domains based on modelling the Carpathians subduction zone

Abstract:

A number of Mediterranean subduction systems are assumed to be the product of narrow oceanic lithosphere (200-300 km wide) subductions. In fully coupled two-dimensional thermo-mechanical numerical models such oceanic domains are too narrow to generate the features that can be inferred from geodynamic reconstructions and observations (detachment of the subducting slab, extension of the upper plate) in these subduction systems.

To properly explain the features of the Eastern Carpathians Mountain Range, one such Mediterranean-style system, we started to work towards developing a numerical model, where we assume a much wider oceanic domain (1000 km), representing two components, both subducted by the upper plate.
The first component is an older ocean (700 km wide) that represents a former subduction system. The second component is the aforementioned narrow ocean (300 km wide). We assumed no rheological and thermal difference between the two components.

In this contribution we show that such wider oceanic lithosphere can ensure sufficient slab-pull to generate roll-back in the Carpathians realm.

The initial model setup is based on contemporary mantle structure and geodynamic reconstructions. Several parameters and their variations, such as the temperature distribution, and crustal rheological parameters, were explored.

Once a model with the required observed features is achieved seismo-thermo-mechanical modelling will be performed to better understand intermediate depth seismicity in the Vrancea-zone under the Eastern Carpathians.