Where does the question come from?

In 2022, I conducted systematic numerical simulations on the dynamics of mid-ocean ridge subduction, focusing specifically on the distinct geological evolution along the western and eastern Pacific continental margins. Sometime after publishing the paper, while idly reviewing the simulation results one day, I made a surprising observation: when slab break-off occurred near the ridge-trench collision zone, the subducting plate didn't immediately stop moving. Instead, at the very moment of break-off, its speed actually increased briefly. Because the time steps in my initial simulations were relatively coarse, this phenomenon flashed by almost instantaneously in the models, and I hadn't paid much attention to it at the time.

Fast forward to the summer of 2023. I had completed my postdoc at Sun Yat-sen University but hadn't secured a new position yet, leaving me at home for about half a year. Our rented apartment was on the 27th floor. During those idle days, I often found myself pacing between the living room and the balcony. It was then that I noticed something: when strong winds blew outside, opening the balcony door barely created a draft inside the living room. However, the moment I opened the main apartment door – even just a slight crack – wind would immediately roar through the apartment, scattering objects everywhere.

That's when the connection struck me: Slab break-off is like that door. Once it opens – once that connection is made – pent-up forces are unleashed, causing dramatic and potentially accelerated movement, just like the sudden, violent wind rushing through the opened apartment door. The slab break-off creates a pathway, and when it happens, the system reacts powerfully and rapidly.

Then I was back to my scientific question. An interesting observation shows that plate convergences in different slab detachment zones are highly varied. The Himalayas orogen shows pronounced uplift. The Mediterranean-Carpathian and Zagros orogens show relatively modest uplift. In circum-Pacific subduction zones, episodes of slab detachment appear to have enhanced compression tectonics along the suture zones, but only with minor uplift (< 1.0 km) of overriding plates. The dynamic effect of slab detachment, especially considering the complex and variable nature of subduction-collision processes, has not been explicitly demonstrated yet.

Plate convergence in response to slab detachment

We distinguish the tectonic settings of slab detachment into ridge-trench collision and continent-trench collision scenarios from a global perspective. Through numerical modeling, we demonstrate that plate convergence can be caused by mantle flow induced by slab detachment and regulated by lithospheric mantle-ridge interaction. Spreading ridge-trench collision has minimal effects on the deformation of overriding plates, whereas continent-trench collision can lead to substantial tectonic uplift at suture zones. Mid-ocean ridges bounding incoming plates accelerate plate motion in ridge-trench collision scenarios and induce considerable tectonic uplift in continent-trench collision scenarios.

Slab detachment role in the present-day plate tectonics

To reveal the effect of slab detachment on mantle flow, we analyzed the spatial distribution of the magnitude and direction of horizontal mantle flow and its relationship to slab detachment. Then, we quantified the effect of mantle drag versus plate drag.  The results show obvious mantle-driven drag at the Chile continental margin, slight mantle-driven drag at the Southern Costa Rica region, and plate-driven drag at the Baja California Sur continental margin in ridge-trench collision zones. In continent-trench collision zones, it shows obvious mantle-driven drag at the Mediterranean-Carpathian and Zagros regions and slight mantle-driven drag along the Himalayas region.

Slab detachment role during the Cenozoic

We compare the modeling results with geological observations from ridge-trench collision and continent-trench collision zones. The vigorous mantle flow triggered by slab detachment may provide additional forces that drive the Pacific plate moving toward the trench in the same direction shortly after the cessation of the Izanagi plate subduction and the corresponding acceleration of the Farallon-Pacific ridge spreading. The time of slab detachment of the India continent is consistent with the rapid uplift along the Himalayas suture zone, which is accompanied by the slight fluctuation of the Carlsberg ridge spreading.

Looking Forward

It is also necessary to acknowledge the limitations of our study - the single slab detachment event in our model results in a short duration of mantle-driven plate convergence. While vertical plate deformation can be recorded by topography, short-duration rapid plate motion is hard to be recorded. Future work with multiple slab detachment events that lasted for a long geological time will help to refine our understanding of the complex lithosphere-mantle interaction beneath collisional belts. 

Yangming Wu^*, Manuele Faccenda, Jie Liao, Jianke Fan, Feng Guo & Zhongping Lai. Mantle-driven plate convergence due to slab detachment. Communications Earth & Environment, 2025, 6. https://doi.org/10.1038/s43247-025-02484-x