The transition from oceanic subduction to continent-continent collision is marked by several diagnostic geological signatures: cessation of arc volcanism, cessation of marine sedimentation as the intervening ocean closes, and a sharp drop in relative plate convergence rate due to the buoyant resistance of two colliding continental plates. Post-collisional uplift and associated erosion/weathering, by contrast, are longer-term consequences that develop progressively after collision is underway, rather than being direct markers of the initial transition.
As an ocean basin closes and subduction gives way to continent-continent collision: (1) island-arc magmatism ends because there is no more oceanic slab being subducted...
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