Subduction Interface Rheology: Accretion, Detachment, Exhumation.pdf

The study, presented in Geophysical Research Abstracts, explores the short- and long-term rheology of the subduction plate interface, focusing on accretion, underplating, detachment, and exhumation processes. The authors examine km-scale accreted terranes and units in both ancient and modern subduction zones, indicating shifts in strain localization.

Key findings include:

1. Episodic Exhumation: Exhumation events are episodic, occurring over millions of years within the 100-million-year lifespan of typical subduction zones.

2. Depth-Dependent Mechanisms: The slicing of km-scale units predominantly occurs at specific depths (30-40 km and 70-80 km) where significant mechanical changes happen along the interface, suggesting that switches in rheology control detachment.

3. Role of Rheology and Fluids: Changing rheologies and fluid presence affect the potential to retrieve rocks and units, with strong viscous coupling promoting metamorphic soles accretion.

4. Long-Term Coupling Variations: Mechanical coupling likely varies throughout subduction, depending on the effective viscosity contrast across the interface, influencing underplating and the formation of high-temperature knockers (eclogites).

5. Link to Seismicity: The study discusses the potential connection between strain localization mechanisms leading to tectonic slicing and seismic activity, particularly in light of recent findings of eclogite breccias.