Integration of natural data within a numerical model of ablative subduction: A possible interpretation for the Alpine dynamics of the Austroalpine crust

TL;DR

This study uses numerical modeling to validate the ablative subduction mechanism as an explanation for the tectonic and metamorphic evolution of the Austroalpine crust in the Alps, showing good agreement with natural data in the Western Alps.

Contribution

It demonstrates that ablative subduction with specific geological processes can reproduce the observed tectono-metamorphic features of the Western Alps' Austroalpine domain.

Findings

Model predictions match natural P-T conditions and exhumation chronology in the Western Alps.

Ablative subduction explains the pre-collisional evolution of the Austroalpine domain.

Discrepancies in the Central-Eastern Alps suggest additional factors influence tectonic evolution.

Abstract

A numerical modelling approach is used to validate the physical and ge- ological reliability of the ablative subduction mechanism during Alpine con- vergence in order to interpret the tectonic and metamorphic evolution of an inner portion of the Alpine belt: the Austroalpine Domain. The model pre- dictions and the natural data for the Austroalpine of the Western Alps agree very well in terms of P-T peak conditions, relative chronology of peak and exhumation events, P-T-t paths, thermal gradients and the tectonic evolu- tion of the continental rocks. These findings suggest that a pre-collisional evolution of this domain, with the burial of the continental rocks (induced by ablative subduction of the overriding Adria plate) and their exhumation (driven by an upwelling flow generated in a hydrated mantle wedge) could be a valid mechanism that reproduces the actual tectono-metamorphic config- uration of this part of the Alps. There is less agreement between the model predictions and the natural data for the Austroalpine of the Central-Eastern Alps. Based on the natural data available in the literature, a critical discus- sion of the other proposed mechanisms is presented, and additional geological factors that should be considered within the numerical model are suggested to improve the fitting to the numerical results; these factors include varia- tions in the continental and/or oceanic thickness, variation of the subduction rate and/or slab dip, the initial thermal state of the passive margin, the oc- currence of continental collision and an oblique convergence.