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Towards understanding the tectonic evolution from magma-poor rifted margins to the Alpine orogen: Insights from 2D and 3D numerical modeling

English title Towards understanding the tectonic evolution from magma-poor rifted margins to the Alpine orogen: Insights from 2D and 3D numerical modeling
Applicant Schmalholz Stefan Markus
Number 144250
Funding scheme Project funding (Div. I-III)
Research institution Institut de géologie et de paléontologie Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Geology
Start/End 01.11.2012 - 31.10.2015
Approved amount 165'852.00
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Keywords (6)

Western Alps; High-performance computing; Magma-poor rifted margin ; Alpine orogeny; Numerical modeling; Mountain building processes

Lay Summary (English)

Lead
Lay summary
The understanding of the geodynamic evolution of the Alps is still incomplete. The Alps contain the remains of two Jurassic- to Cretaceous-age ocean basins, the Valais and Piemont–Liguria oceans. In Cenozoic time, the former magma-poor rifted margins adjoining these basins were accreted to the upper plate of the Alpine orogen. These magma-poor margins exhibited features such as exhumed subcontinental mantle, crustal-scale detachment zones and strongly-extended continental crust. The dynamic control of these pre-orogenic rift-related structures on the subsequent subduction initiation, nappe formation and burial and exhumation of ultra-high-pressure rocks during the Alpine orogeny is largely unknown. We perform 2D numerical simulations of lithospheric extension (generating magma-poor rifted margins) and subsequent compression to investigate the control of pre-orogenic rift-related features on the tectonic evolution of the Western Alps. The applied 2D numerical models are based on the finite element method. Lithospheric extension and subsequent compression will be modeled within a single simulation. This approach guarantees consistent results, because the pre-compression rifted margin structures are the result of a numerical simulation and the same algorithm that generated the rift structures is used to model the compressional deformation. 2D simulations will be applied to investigate (1) the subduction initiation and dynamics at magma-poor rifted margins, (2) the burial and exhumation of ultra-high-pressure rocks during compression, (3) the impact of different softening mechanisms and (4) the control of pre-orogenic weak detachment zones, formed during extension, on the compressional deformation. The numerical results will be compared with available geological and geophysical data (e.g. geological cross sections). A model will be determined, which yields results that fit best the first-order features of the tectonic evolution of the Western Alps.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Viscous overthrusting versus folding: 2-D quantitative modeling and its application to the Helvetic and Jura fold and thrust belts
Jaquet Yoann, Bauville Arthur, Schmalholz Stefan M. (2014), Viscous overthrusting versus folding: 2-D quantitative modeling and its application to the Helvetic and Jura fold and thrust belts, in Journal of Structural Geology, 62, 25-37.
Dramatic effect of elasticity on thermal softening and strain localization during lithospheric shortening
Jaquet Yoann, Duretz Thibault, Schmalholz Stefan Markus, Dramatic effect of elasticity on thermal softening and strain localization during lithospheric shortening, in Geophysical Journal International.

Collaboration

Group / person Country
Types of collaboration
Prof. Dr. Othmar Müntener Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Prof. Dr. Yuri Podladchikov Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Prof. Dr. Boris Kaus Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Prof. Dr. Jean-Luc Epard Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
European Geoscience Union, General Assembly 2016 Poster Self-consistent orogenic wedge formation and shear zone propagation due to thermal softening 17.04.2016 Vienna, Austria Schmalholz Stefan Markus; Jaquet Yoann;
Swiss Geoscience Meeting 2015 Poster Formation of necking zones during lithospheric rifting 20.11.2015 Basel, Switzerland Schmalholz Stefan Markus; Jaquet Yoann;
Emile Argand Conference on Alpine Geological Studies Poster Formation of necking zones during lithospheric rifting 14.09.2015 Montgenèvre-Briançon, France Jaquet Yoann; Schmalholz Stefan Markus;
European Geoscience Union, General Assembly 2015 Poster Impact of elasticity on lithospheric shear localization 12.04.2015 Wien, Austria Schmalholz Stefan Markus; Jaquet Yoann;
Swiss Geoscience Meeting 2014 Poster Impact of elasticity on lithospheric shear localization 16.11.2014 Fribourg, Switzerland Schmalholz Stefan Markus; Jaquet Yoann;
European Geoscience Union, General Assembly 2014 Poster Viscous overthrusting versus folding: 2D numerical modeling and application to the Helvetic and Jura fold-and-thrust belts 27.04.2014 Wien, Austria Jaquet Yoann; Schmalholz Stefan Markus;
European Geoscience Union, General Assembly 2015 Poster Impact of rheological layering on rift asymmetry 12.04.2014 Wien, Austria Schmalholz Stefan Markus; Jaquet Yoann;
DPMS Spring Day 2014 Talk given at a conference Control of the pre-Alpine ocean basin architecture on the Alpine orogeny: Insights from quantitative models 04.04.2014 Lausanne, Switzerland Schmalholz Stefan Markus; Jaquet Yoann;
AGU Fall Meeting 2013 Poster Viscous overthrusting versus folding: 2D numerical modeling and application to the Helvetic and Jura fold-and-thrust belts 09.12.2013 San Francisco, United States of America Jaquet Yoann; Schmalholz Stefan Markus;
Swiss Geoscience Meeting 2013 Poster Viscous overthrusting versus folding: 2D numerical modeling and application to the Helvetic and Jura fold-and-thrust belts 16.11.2013 Lausanne, Switzerland Schmalholz Stefan Markus; Jaquet Yoann;
CADMOS Activity Days 2013 Poster Viscous overthrusting versus folding: 2D numerical modeling and application to the Helvetic and Jura fold-and-thrust belts 24.10.2013 Leysin, Switzerland Jaquet Yoann; Schmalholz Stefan Markus;
Emile Argand Conference on Alpine Geological Studies Poster Viscous overthrusting versus folding: 2D numerical modeling and application to the Helvetic and Jura fold-and-thrust belts 07.09.2013 Schladming, Austria Jaquet Yoann; Schmalholz Stefan Markus;


Associated projects

Number Title Start Funding scheme
163169 Towards a self-consistent dynamic orogenic wedge model for the Western Alps 01.11.2015 Project funding (Div. I-III)
131897 Towards understanding fold nappe dynamics in the Western Swiss Alps 01.10.2010 Project funding (Div. I-III)
149380 Towards understanding the dynamics of tectonic nappe stacking and overthrusting in the Helvetic nappe system 01.11.2013 Project funding (Div. I-III)

Abstract

The understanding of the geodynamic evolution of the Alps is still incomplete. The Alps contain the remains of two Jurassic- to Cretaceous age ocean basins, the Valais and Piemont-Liguria oceans. In Cenozoic time, the former magma-poor rifted margins adjoining these basins were accreted to the upper plate of the Alpine orogen. These magma-poor margins exhibited features such as exhumed subcontinental mantle, crustal-scale detachment zones and hyper-extended continental crust. The dynamic control of these pre-orogenic rift-related structures on the subsequent subduction initiation, nappe formation and burial and exhumation of ultra-high-pressure rocks during the Alpine orogeny is largely unknown. Also, the 3D kinematics and dynamics of the Western Alps are not fully understood. We propose to perform 2D and 3D numerical simulations of lithospheric extension (generating magma-poor rifted margins) and subsequent compression to investigate the control of pre-orogenic rift-related features on the tectonic evolution of the Western Alps. The applied numerical algorithms for 2D and 3D deformations are based on the finite element and finite difference methods and can handle large deformations. The 2D and 3D models will include viscoelastoplastic rheologies with a Mohr-Coulomb plasticity criterion and temperature dependent viscosities. Strain softening will be modeled and investigated by three approaches: (1) reducing the friction angle over a certain interval of plastic strain, (2) shear heating coupled with temperature dependent viscosities and (3) considering a mechanically multi-layered crust causing structural softening by formation of shear zones in extension and multi-layer folds in compression. Lithospheric extension and subsequent compression will be modeled with the same algorithm and within a single simulation. This approach guarantees thermo-mechanically as well as numerically consistent results, because the pre-compression rifted margin structures are the result of a numerical simulation and the same algorithm that generated the rift structures is used to model the compressional deformation. 2D simulations will be applied to investigate (1) the subduction initiation and dynamics at magma-poor rifted margins, (2) the burial and exhumation of ultra-high-pressure rocks during compression, (3) the impact of different softening mechanisms and (4) the control of pre-orogenic weak detachment zones, formed during extension, on the compressional deformation. 3D simulations will be applied to investigate (1) lateral propagation of mantle exhumation and crustal thinning during formation of magma-poor rifted margins, (2) the impact of strike-slip faulting during lithospheric extension and compression, and (3) the impact of laterally varying geometries on the compressional deformation. Several leading-edge numerical algorithms for 2D and 3D deformations are available and will be applied, elaborated and adjusted to perform the simulations. The numerical simulations will be performed on the high-end computational cluster Achilles at University of Lausanne and on the BlueGene supercomputer at EPF Lausanne. The numerical results will be compared with available geological and geophysical data (e.g. geological cross sections and reconstructions). For both the 2D as well as the 3D model a corresponding setup (i.e. initial and boundary conditions, softening mechanism, rheological parameters, etc.) will be determined, which yields results that fit best the first-order features of the tectonic evolution of the Western Alps. We request two PhD students to perform this study, integrating computational tectonics with geological and geophysical data from the Western Alps. The first PhD student will perform high-resolution 2D simulations and the second one will perform 3D simulations. Both students will collaborate for applying the numerical results to the Western Alps and for benchmarking the 3D and 2D algorithms. The results of this project will improve our understanding of mountain building processes in 3D and the geodynamic evolution of the Western Alps. The project involves collaboration with other scientists of the Faculty of Geosciences and Environment at the University of Lausanne and with the group of Prof. Boris Kaus at the University of Mainz, Germany.
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