Subduction zone initiation
Why is SZI important?
Subduction is the main mechanism by which the Earth’s outer layer is recycled into its interior, thereby driving ocean-plate tectonics. The initiation of new subduction zones is key to maintain this process, which differentiates the Earth from all other known rocky planets, over geologic time periods.
Better understanding SZI is therefore important to better understand why the Earth is unique, how life was able to evolve, and why and how two of the major threats for humanity, earthquakes and volcanic eruptions, occur.
How can we observe SZI?
It is difficult to observe SZI directly in part due to the long, Million year timescales involved. However, past SZI events can be inferred from the combination of both direct evidence in the geologic record and interpretations performed on geophysical measurements.
SZI-ophiolites (or their individual rock sequences) and Metamorphic soles provide direct evidence for juvenile subduction of an oceanic plate. When at least some of these rock sequences are deposited on the more long-living portions of the Earth's surface (e.g., continents), they can provide a key record of past SZI.
Combining such direct evidence with interpretations made through plate reconstruction, seismic tomography and geodynamic forward models, allows us to infer SZI, how and when it happened, within an acceptable amount of uncertainty.
How does SZI work?
When did SZI happen on the Earth?
Where does SZI happen on the Earth?