Control of 3-D tectonic inheritance on fold-and-thrust belts: insights from 3-D numerical models and application to the Helvetic nappe system

Three-dimensional tectonic inheritance plays a fundamental role in the evolution of fold-and-thrust belts, significantly influencing nappe formation and deformation patterns. This study demonstrates that initial basement horst and graben structures, along with laterally variable sedimentary layer strengths, control the detachment, folding, and horizontal transport of sedimentary units. Deeper half-grabens generate thicker nappes and more intense deformation in adjacent horsts, while shallower ones produce thinner nappes and less deformation. Mechanically weaker basements favor fold nappes, whereas stronger basements promote thrust sheets. The research applies 3-D thermo-mechanical numerical simulations to the Helvetic nappe system of the Central Alps, reproducing key features such as the closure of half-grabens, overthrusting, and nappe stacking, aligning with observed finite strain patterns, temperature distributions, and timing data. Strain localization and nappe transport are driven by initial geometrical and mechanical heterogeneities, highlighting the critical importance of tectonic inheritance in fold-and-thrust belt dynamics.

Spitz, R., Bauville, A., Epard, J.-L., Kaus, B. J. P., Popov, A. A., & Schmalholz, S. M. (2020). Control of 3-D tectonic inheritance on fold-and-thrust belts: insights from 3-D numerical models and application to the Helvetic nappe system. Solid Earth, 11(3), 999–1026. https://doi.org/10.5194/se-11-999-2020