divergent double subduction

Fun geology term of the day: divergent double subduction

After writing my previous post about double subduction, I did a quick search for the term to see where else it is used. I found this cool article published in Geology in 1997. Soesoo et al. (1997) describe a process called divergent double subduction (see figure below) where subduction of an oceanic plate occurs on both sides until the two overriding plates meet and the remaining plate sinks into the mantle. Soesoo and coauthors argue that such a process will produce quite a bit of volcanism in at least two processes: 1) decompression melting of asthenosphere as it rises to take the place of the sinking plate, and 2) flux melting driven by dehydration of the sinking plate to greater pressures. The remnants of divergent double subduction is suggested to be found in the abundant Paleozoic magmatism of the Lachlan fold belt in southeastern Australia.

 Image from figure 1 of Soesoo et al., 1997

Citation: Soesoo, I., Bons, P., Gray, D.,  and Foster, D., 1997, Divergent double subduction: Tectonic and petrologic consequences, Geology, v. 25, p. 755-758