Where data-based structure meets process simulation - how heterogeneities relate to lithosphere deformation in the Alps

Abstract

To address the question of how the present-day architecture of the lithosphere and the heterogenous density configuration of the uppermost mantle influence deformation in the Alpine orogenic system we use data-derived 3D configurations as input to dynamic simulations. This includes on the one hand the consideration of a detailed crustal model of the Alpine region and its forelands that resolves first-order contrasts in the thermophysical properties of the crust consistent with available geoscientific observables (active and passive seismic, gravity, geological, geothermal). In addition, we tested an ensemble of configurations of upper mantle thermophysical properties derived from published seismic tomography models. Using a Gibbs-free energy minimization algorithm (https://zenodo.org/records/6538257) we convert the results of regional shear-wave seismic tomography models to temperature models and define the base of the lithosphere and the geometry of slabs in the asthenosphere with a threshold temperature of 1300°C. As a first step we model topography and deformation velocities as resulting from buoyancy-forces driven by a quasi-instantaneous flow resulting from the first-order rheological structure of the lithosphere-asthenosphere system using the open source geodynamic code LaMEM (https://github.com/UniMainzGeo/LaMEM). The simulation results indicate that a slab detached beneath the Alps, but attached beneath the Northern Apennines captures first-order patterns in topography, vertical surface velocities, and mantle flow. The presence of an attached slab beneath the northern Apennines also explains the observed sub-crustal seismicity in contrast to the seismicity in the Alps restricted to the upper-crustal domain.

Authors 6

1. Magdalena Scheck‐Wenderoth corresponding Aachen Faculty of Georesources and Materials Engineering

   GFZ Helmholtz Centre for Geosciences · RWTH Aachen University

   Affiliation as printed

   Faculty of Georesources and Materials Engineering, RWTH Aachen University, Aachen, Germany

   Helmholtz Centre Potsdam GFZ, Department 4 Geosystems, Section 4.5 Basin Modeling, Potsdam, Germany (leni@gfz-potsdam.de)

2. Ajay Kumar corresponding

   GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   Helmholtz Centre Potsdam GFZ, Department 4 Geosystems, Section 4.5 Basin Modeling, Potsdam, Germany (leni@gfz-potsdam.de)

3. Mauro Cacace corresponding

   GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   Helmholtz Centre Potsdam GFZ, Department 4 Geosystems, Section 4.5 Basin Modeling, Potsdam, Germany (leni@gfz-potsdam.de)

4. Judith Bott corresponding

   GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   Helmholtz Centre Potsdam GFZ, Department 4 Geosystems, Section 4.5 Basin Modeling, Potsdam, Germany (leni@gfz-potsdam.de)

5. Hajo Götze

   Christian-Albrechts-Universität zu Kiel

   Affiliation as printed

   Institute of Geosciences, Christian-Albrechts-University of Kiel, Kiel, Germany

6. Boris J. P. Kaus corresponding

   Johannes Gutenberg University Mainz

   Affiliation as printed

   Institute of Geosciences, Johannes Gutenberg University of Mainz, Mainz, Germany