Revision 1

Accepted · first revision · record

Title: How do new subduction zones start?
Plain: Plate tectonics needs plates to sink back into the mantle at subduction zones, but a strong intact plate resists being bent and broken to start sinking. Whether new subduction zones begin by themselves or are pushed by neighboring plates is debated.
Precise: Determine the conditions under which subduction initiates: spontaneously (gravitational foundering of old dense lithosphere along a weak zone) or induced (by plate convergence), and the roles of mantle plumes and inherited weak zones. An answer is a criterion in terms of lithospheric age, weak-zone strength and applied force, from thermomechanical models with lab-constrained rheology, tested against Cenozoic initiation events such as Izu-Bonin-Mariana near 52 Ma (review: Stern and Gerya, Tectonophysics 2018, https://doi.org/10.1016/j.tecto.2017.10.014).
Settled by: Dated magmatic and stratigraphic records of forearcs at young subduction zones compared with thermomechanical models using only experimentally constrained rheology.
Kind: well-posed
Answer type: mechanism
References: (empty)
Literature status: contested
Status note: Ocean drilling of the Izu-Bonin-Mariana forearc in 2014 recovered the volcanic sequence expected from spontaneous initiation; whether induced initiation dominates elsewhere remains debated.
Posed since: (empty)