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Subduction Polarity Reversal

We’ve been talking a lot about the Wilson Cycle in which continents rift, opening basins that become oceans, that widen until a subduction zone helps to reverse the divergent motion to convergency. But plate tectonics can be so much more complex than that. One of the complications that occurs is subduction polarity reversal (aka flipping subduction polarity, my favorite:)

Subduction Polarity Reversal happens when two converging plates meet and one plate overrides the other, then they switch and the overridden plate becomes the overriding plate. See the model from AGU in the video below.

Examples of SPR include Taiwan, the Solomon Islands, the Alps Apennines, Italy, and many more.

There are many proposed mechnisms of SPR such as slab break-off and mantle window, double convergence with slab break-off, and others.

One recent study with the fun name of “Breaking Up Is Hard to Do: Magmatism During Oceanic Arc Breakup, Subduction Reversal, and Cessation” by James Gill, et al, (link below) proposes that subduction of Samoan seamounts broke up the former Vanuatu portion of the subduction zone, flipping that portion of the subduction zone to west of Vanuatu. (see figure 2 below)

Thank you, and tip of the hat to Peggy March @RebelGeo

New modeling shows how subduction zones can reverse polarity: https://youtube.com/watch?v=IsLOuZubboc&feature=share

“Breaking Up Is Hard to Do: Magmatism During Oceanic Arc Breakup, Subduction Reversal, and Cessation” by James Gill, et al:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GC010663#.Y6yDFL7fX_g.twitter

#SubductionPolarityReversal #WilsonCycle #VanuatuArc #TongaTrench #geology @geology #Science