Abstract

Thermal-mechanical numerical experiments are used to consider if the influence of surface erosion during continental plate collision and orogenesis extends beneath the crust into the mantle lithosphere. The models demonstrate that the modification of crustal mass flux by surface denudation can change the evolution of the deforming crust and consequently alter the behavior of the crust-mantle interface. The mantle lithosphere responds to these variable dynamics: with active surface erosion, stable subduction-like plate consumption is maintained; in the absence of erosion, subduction is inhibited by accumulating crust, causing the convergent plates to steepen dip, detach, and reverse consumption polarity. With strong subducting plates, the removal of surface processes can trigger a transition from stable subduction to delamination and/or retreat of the convergent plate. The influence of surface erosion is less important for mantle lithosphere undergoing Rayleigh-Taylor–type dripping and is not significant at ocean plate collision, where there is relatively little buoyant crust to clog the subduction zone. The results of the experiments demonstrate that in certain tectonic regimes the influence of climate-controlled surface processes may reach much deeper into the lithosphere than has previously been appreciated.

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