Where do the biggest diamonds come from? Geology now has answers
9 hours ago
- CLIPPIR diamonds are rare superdeep diamonds forming more than 400 km deep in Earth's mantle transition zone, unlike ordinary diamonds that form at depths up to 200 km.
- They originate from ancient oceanic crust that was dragged deep into the mantle by plate tectonics and transformed into diamond under extreme conditions.
- New research on olivine chemistry in kimberlite rocks reveals that CLIPPIR diamonds are associated with iron-rich domains in the mantle, linked to hydrothermally altered basaltic oceanic crust.
- The dense iron-rich rocks hosting these diamonds cannot rise passively; they likely require mantle plumes for upward transport before being stored at the base of continental roots for hundreds of millions of years.
- Kimberlite magmas eventually carry these diamonds to the surface, recording a long geological journey from seafloor to deep mantle to surface.
- The findings provide a practical tool for diamond exploration: kimberlites with abundant iron-rich olivine have higher potential to host CLIPPIR diamonds, guiding exploration in regions like Sierra Leone and Angola.