10.5880/fidgeo.2021.023 Eisermann, Jan Oliver Jan Oliver Eisermann 0000-0002-3350-0445 Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany Göllner, Paul Leon Paul Leon Göllner Universität Hamburg, Hamburg, Germany Riller, Ulrich Ulrich Riller 0000-0002-3803-6792 Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany GFZ Data Services 2021 GPS velocity field kinematic partitioning Strain partitioning Southern Andes Transpression oblique plate convergence analogue experiment modeling Liquiñe-Ofqui Fault Zone interseismic deformation Multibox EPOS European Plate Observing System multi-scale laboratories analogue models of geologic processes analog modelling results Digital Image Correlation (DIC) / Particle Image Velocimetry (PIV) > StrainMaster (La Vision GmbH) EARTH SCIENCE > SOLID EARTH > GEODETICS EARTH SCIENCE > SOLID EARTH > TECTONICS > PLATE TECTONICS > STRAIN EARTH SCIENCE SERVICES > MODELS > GEOLOGIC/TECTONIC/PALEOCLIMATE MODELS fault > oblique slip fault fault > strike-slip fault geologic process Glass/Plexiglas box > Glass/Plexiglas box (meter scale) Microspheres > Glassy normal fault Sand > Corundum Sand Sand > Quartz Sand Sandbox > Sandbox (meter scale) Shear box Silicon/Silly putty/PDMS Squeeze box Surface image tectonic and structural features tectonic process > orogenic process tectonic setting > back arc setting tectonic setting > plate margin setting > active continental margin setting tectonic setting > plate margin setting > volcanic arc setting Time lapse camera Eisermann, Jan Oliver Jan Oliver Eisermann 0000-0002-3350-0445 Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany Göllner, Paul Leon Paul Leon Göllner Universität Hamburg, Hamburg, Germany Riller, Ulrich Ulrich Riller 0000-0002-3803-6792 Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany Riller, Ulrich Ulrich Riller 0000-0002-3803-6792 Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany Analogue modelling laboratory (University Hamburg, Germany) Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany Riller, Ulrich Universität Hamburg, Hamburg, Germany 2021-04-20 Dataset 10.1038/s43247-021-00241-4 CC BY 4.0 The southern Andes are regarded as a typical subduction orogen formed by oblique plate convergence. Despite decades of studies, there is considerable uncertainty as to how deformation is kinematically partitioned in the upper plate. Using scaled analogue experiments modelling, we test the concept of dextral transpression for this orogen. We advocate that the GPS velocity field portrays interseismic deformation related to deformation of strong crust north, and weak crust south, of 37°S. Contrary to the popular hypotheses that the Liquiñe-Ofqui Fault Zone, a prominent intra-arc deformation zone, takes up most of the plate boundary-parallel dextral strike-slip, we find that dextral transpression affects the entire model orogen through tectonic segmentation of crust.

Moreover, prominent, regularly spaced sinistral oblique-slip thrust faults, interpreted as antithetic Riedel shears, developed spontaneously in all of our experiments and call into question the general believe that their NW-striking natural equivalents formed from pre-Andean discontinuities. Our experiments prompt us to reconsider the apparently well-established geodynamic concept that strain and margin-parallel displacement is localized on a few margin-parallel faults in the southern Andes.
study area represented by the model -74.4747 -68.4103 -42.1428 -34.2115 German Science Foundation 10.13039/501100001659 355640964 Volcano-tectonics under intra-arc transpression