Trench retreat rates in narrow subduction zones controlled by overriding plate thickness
- 1Department of Theoretical Physics and Cosmology, University of Granada, Granada, Spain
- 2Andalusian Institute of Geophysics and Prevention of Seismic Disasters, University of Granada, Granada, Spain
- 3Department of Earth Physics and Astrophysics, Complutense University of Madrid, Madrid, Spain
- 4Institute of Geosciences IGEO (CSIC, UCM), Madrid, Spain
- 5Department of Earth Sciences, Durham University, DH1 3LE Durham, UK
Subducting slabs are the main drivers of plate motion and flow in Earth’s mantle. Thus, much effort has been put into understanding the main factors controlling slab dynamics and subduction-induced mantle flow. Slab width (W) has been shown to have a major role in controlling the subduction dynamics and more specifically, the trench motion (e.g., Stegman et al., 2006; Schellart et al., 2007). Both numerical modelling experiments and retreat velocities observed in wide subduction zones show that the trench retreat velocity (VT) decreases as the slab is wider. However, observations on natural narrow subduction zones (W ≤ 1000 km, e.g. Calabria, Gibraltar, Scotia) do not show a direct relation between W and VT, thus indicating that other factors, still poorly understood, may play a more relevant role on trench retreat velocities. The aim of this work is to identify which are these factors that exert a dominant control. To accomplish this, we use self-consistent 3D numerical subduction models to systematically evaluate the effect of slab width, strength of coupling with the lateral plate and overriding plate thickness on trench motion. In contrast to what happens in moderate to wide subduction zones, our simulations show that slab width has little influence on trench retreat velocity for narrow subduction zones, which is a robust result for different viscous couplings at the lateral slab edge. On the contrary, our results indicate that the major influence is exerted by the thickness of the overriding plate, with the trench retreat velocities decreasing noticeably as the plate thickness increases. These results are in agreement with retreat velocities observed in narrow subduction zones showing no direct relation with slab width, but an inverse dependence on overriding plate thickness.
References
Schellart, W. P., Freeman, J., Stegman, D. R., Moresi, L., and May, D. (2007). Evolution and diversity of subduction zones controlled by slab width, Nature, 446(7133), 308–311. doi:10.1038/nature05615
Stegman, D. R.; Freeman, J.; Schellart, W. P.; Moresi, L.; May, D. (2006). Influence of trench width on subduction hinge retreat rates in 3-D models of slab rollback, Geochemistry Geophysics Geosystems, 7(3), Q03012–. doi:10.1029/2005gc001056
How to cite: Gea, P. J., Mancilla, F. D. L., Negredo, A. M., and van Hunen, J.: Trench retreat rates in narrow subduction zones controlled by overriding plate thickness, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-7314, https://doi.org/10.5194/egusphere-egu23-7314, 2023.
