The Hindu Kush slab break-off as revealed by deep structure and crustal deformation.
Break-off of part of the down-going plate during continental collision occurs due to tensile stresses built-up between the deep and shallow slab, for which buoyancy is increased because of continental-crust subduction. Break-off governs the subsequent orogenic evolution but real-time observations are rare as it happens over geologically short times. Here we present a finite-frequency tomography, based on jointly inverted local and remote earthquakes, for the Hindu Kush in Afghanistan, where slab break-off is ongoing. We interpret our results as crustal subduction on top of a northwards-subducting Indian lithospheric slab, whose penetration depth increases along-strike while thinning and steepening. This implies that break-off is propagating laterally and that the highest lithospheric stretching rates occur during the final pinching-off. In the Hindu Kush crust, earthquakes and geodetic data show a transition from focused to distributed deformation, which we relate to a variable degree of crust-mantle coupling presumably associated with break-off at depth.
Authors: Kufner, Sofia-Katerina ORCID record for Sofia-Katerina Kufner, Kakar, N., Bezada, M., Bloch, W., Metzger, S., Yuan, X., Mechie, J., Ratschbacher, L., Murodkulov, S., Deng, Z., Schurr, B.