Ophiolites: A window on past subduction initiation events

More than 40,000 km of active subduction zones cut today the Earth’s crust, continuously consuming and recycling lithosphere into the mantle. The study of these subduction zones in the past 70 years has been instrumental to further our knowledge on the mechanisms that generate earthquakes, and more in general on how plate tectonics works. However, lots still need to be understood about how these subduction zones formed, in other words, how subduction initiation operates. Our poor understanding of subduction initiation stems by the lack of modern analogues of incipient subduction zones. For this reason, studying past subduction initiation events is key to shed lights on this complex and fascinating topic. In this presentation I will discuss how we can use ophiolites as a window on past subduction initiation events, and how we can quantitatively constrain the style of subduction initiation (i.e., forced or spontaneous), the timing, and the geometry of these ancient subduction zones.