The role of lithospheric-deep mantle interactions in modulating the landscape evolution of arc-continent collision

<p>The interaction of subducted oceanic lithosphere with the upper-lower mantle transition zone has been documented to cause episodes of increased surface compression and extension at convergent continental margins. However, little is known about how these lithospheric-deep mantle interactions impact the evolution of arc-continent collision margins, where orogenic growth and basin formation/infilling can occur simultaneously. We use 2.5D subduction models that couple the evolution of Earth&#8217;s surface with the geodynamics of the mantle to investigate: (i) how the interactions between the lithosphere and the deep mantle affect the topography evolution of the orogen and basin infilling; and (ii) how sedimentation in the basin modulates the evolution of deformation. Results show that slab-folding in the upper-lower mantle transition zone triggers increased shortening and topographic growth in the orogen by causing the steepening of the subducting slab, which increases the sediment supply to the basin at punctuated times. Furthermore, results show that: (i) the effect of slab-folding in the topography evolution of the orogen and basin infilling increases with the efficiency of surface processes; and (ii) there is a spatial/temporal correlation between the cumulated sedimentation in the basin and the plastic strain. To quantify the strength of this correlation, we performed a Spearman correlation test, which displayed a high correlation between low values of sedimentation (200-1500 m) and low values of plastic strain (0.1-1.5) during the occurrence of slab-folding. In contrast, we found a high correlation between high values of sedimentation (> 1500 m) and plastic strain (>1.5) only when the sedimentation in the basin is 6000 m. We conclude that: (i) the effect of slab-folding in the topography evolution of the orogen and basin infilling is modulated by the efficiency of surface processes (ii) low sedimentation in the basin increases the activity of short wavelength deformation; and (iii) high sedimentation increase the activity of large wavelength deformation during slab-folding only when slab-steepening is maximum.</p>