Boninite
“Lava born from a newborn subduction zone”
Boninite is a rare, magnesium-rich volcanic rock that erupts during the earliest stages of subduction, when one tectonic plate first begins to dive beneath another. Its unusual chemistry requires extremely hot, depleted mantle conditions found only in this specific tectonic setting.
enstatite, clinoenstatite, olivine, chromite, volcanic glass, plagioclase (minor)
Bonin (Ogasawara) Islands (Japan), Troodos (Cyprus), Izu-Bonin-Mariana Arc, Tonga, Papua New Guinea
5.5-6.5
Finding ancient boninites in the rock record helps geologists pinpoint exactly when and where subduction zones first initiated — they're geological time stamps of tectonic birth events.
Test Your Knowledge
What makes the mantle conditions for boninite formation so unusual?
Photo Attribution
Title: Basalto afanitico e quasi afirico per i rari e minuti fenocristalli.jpg
Author: Daniele.51
License: CC BY-SA 4.0
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