Overview
- The peer‑reviewed study, published Oct. 14 in Nature Geoscience, reports a reproducible potassium‑40 deficit in ancient mantle‑derived rocks from Greenland, Canada and Hawaii.
- High‑precision mass spectrometry of isolated potassium from powdered samples revealed the K‑40 shortfall relative to typical terrestrial materials.
- Accretion and impact simulations show the Moon‑forming Theia collision would have increased Earth’s K‑40, indicating the low‑K‑40 signature predates that impact and reflects preserved proto‑Earth mantle.
- The potassium signature differs from all known meteorites, suggesting Earth’s original building materials are not fully represented in current meteorite collections.
- Independent experts describe the potassium‑based interpretation as convincing and say more proto‑Earth material may persist in the deep mantle, motivating broader sampling and modeling to map these domains.