Both convergence velocity and the thickness of sediment entering a subduction zone affect the dynamics of deformation in this environment. Specifically, the steady-state trench model implies that at constant sediment influx and convergence angle, the strain of underthrust trench deposits varies as the first power of convergence rate for a given distance of underthrusting and as the square of convergence rate for a given duration of underthrusting. Trench deposits are probably disrupted during high-strain and high-strain-rate convergent regimes, whereas they may be more coherently deformed in relatively low-strain and low-strain-rate regimes. Variations from coherent to tectonically disrupted terranes may be interpreted in terms of changes in both convergence rate and influx of trench sediments.

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