Overview
- An MIT‑led team reports ancient rocks from Greenland, Canada and Hawaii carry a potassium‑40 deficit unlike typical Earth materials.
- Computer simulations indicate the Theia collision should have enriched Earth in potassium‑40, so the low‑K‑40 signal likely reflects pre‑impact mantle material.
- The potassium fingerprint does not match any known meteorite type, suggesting Earth's original building blocks are missing from current meteorite collections.
- The study, published Oct. 14 in Nature Geoscience, used acid dissolution and high‑precision mass spectrometry to isolate and measure potassium isotopes.
- Independent experts describe the interpretation as convincing and call for broader isotopic surveys and targeted sampling of deep‑mantle‑derived materials.