Localization of deformation in a non-collisional subduction orogen: the
roles of dip geometry and plate strength on the evolution of the broken
Andean foreland, Sierras Pampeanas, Argentina
- Michaël Pons,
- Stephan V. Sobolev,
- Constanza Rodriguez Piceda,
- Magdalena Scheck-Wenderoth,
- Manfred R. Strecker
Michaël Pons
Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Universität Potsdam, Institut für Geowissenschaften, Germany
Corresponding Author:[email protected]
Author ProfileStephan V. Sobolev
Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Universität Potsdam, Institut für Geowissenschaften, Germany
Author ProfileConstanza Rodriguez Piceda
University of Plymouth, School of Geography, Earth and Environmental Sciences, United Kingdom, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Universität Potsdam, Institut für Geowissenschaften, Germany
Author ProfileMagdalena Scheck-Wenderoth
Helmholtz Centre Potsdam, GFZ German Research Centre For Geosciences, RWTH Aachen University, Aachen, Germany
Author ProfileManfred R. Strecker
Universität Potsdam, Institut für Geowissenschaften, Germany
Author ProfileAbstract
The non-collisional subduction margin of South America is characterized
by different geometries of the subduction zone and upper-plate
tectono-magmatic provinces. The localization of deformation in the
southern Central Andes (29°S–39°S) has been attributed to numerous
factors that combine the properties of the subducting oceanic Nazca
plate and the continental South American plate. In this study, the
present-day configuration of the subducting oceanic plate and the
continental upper plate were integrated in a data-driven geodynamic
workflow to assess their role in determining strain localization within
the upper plate of the flat slab and its southward transition to a
steeper segment. The model predicts two fundamental processes that drive
deformation in the Andean orogen and its foreland: eastward propagation
of deformation in the flat-slab segment by a combined bulldozing
mechanism and pure-shear shortening that affects the broken foreland and
simple-shear shortening in the fold-and-thrust belt of the orogen above
the steep slab segment. The transition between the steep and
subhorizontal subduction segments is characterized by a 370-km-wide area
of diffuse shear, where deformation transitions from pure to simple
shear, resembling the transition from thick to thin-skinned foreland
deformation in the southern Sierras Pampeanas. This pattern is
controlled by the change in dip geometry of the Nazca plate and the
presence of mechanically weak sedimentary basins and inherited faults.
24 Jan 2023Submitted to ESS Open Archive 24 Jan 2023Published in ESS Open Archive