Tracing wedge-internal deformation by means of strontium isotope systematics of vein carbonates

Vein carbonates from the Swiss Tectonic Arena Sardona, part of the North Alpine fold-and-thrust belt, reveal critical insights into the tectonometamorphic evolution during continental collision. The study demonstrates that strontium isotope ratios (87Sr/86Sr) in these vein carbonates shift from an initial seawater-like signature to match the host rock's composition as metamorphic grade increases. This isotopic progression reflects the progressive equilibration of pore fluids with the host rock, providing a novel method to constrain deformation events such as bedding-parallel shearing, imbricate thrusting, folding, cleavage development, and mélange formation under diagenetic to low-grade metamorphic conditions. The findings enhance understanding of the prograde to early retrograde tectonic evolution in accretionary wedges.

Dielforder, A., Villa, I. M., Berger, A., & Herwegh, M. (2022). Tracing wedge-internal deformation by means of strontium isotope systematics of vein carbonates. Geological Magazine, 159(11-12), 2191–2205. https://doi.org/10.1017/s0016756821001357