Researchers from Hebrew University's Institute of Earth Sciences have made a groundbreaking discovery that confirms decades-old predictions about Earth's deep mantle. Led by Yael Kempe and Yaakov Weiss, the team identified the first natural evidence of nickel-rich metallic alloys forming at depths of 280–470 km beneath Earth's surface.

Diamonds as Time Capsules

The discovery came from studying inclusions trapped within diamonds from South Africa's Voorspoed mine. The team found nickel-iron metallic nanoinclusions coexisting with nickel-rich carbonates—capturing a "redox-freezing" reaction where oxidized melts infiltrated reduced mantle rock.

"The diamonds act as tiny time capsules, preserving a reaction that would otherwise vanish as minerals re-equilibrate with their surroundings," says Weiss.

Why It Matters

This finding validates theoretical models and offers new insights into how volatile-rich magmas form in the mantle-magmas that eventually erupt and bring diamonds to the surface. The research may also help explain the origins of kimberlites and other magmas that shape our planet.

The study was conducted in collaboration with researchers from the University of Nevada, University of Cambridge, and Hebrew University's Nanocenter.

The research paper titled “Redox state of the deep upper mantle recorded by nickel-rich diamond inclusions” is now available in Nature Geoscience and can be accessed at https://www.nature.com/articles/s41561-025-01791-4

 

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