Yale and Columbia researchers trace Earth’s core carbon to outer solar system

Analysis of Hawaiian lava droplets

Researchers examined magma droplets known as melt inclusions from historic eruptions in Hawaii. These samples include material from Keanakākoʻi eruptions between 1500 and 1840 plus the 1959 Kīlauea Iki event. Each droplet acts as a snapshot of magma conditions deep within the Earth when crystals formed inside them. Yves Moussallam and his group at Columbia's Lamont-Doherty Earth Observatory created this particular observation technique.

Isotopic signatures reveal carbon origins

The study found a uniquely heavy carbon-13 signature in magma believed to originate from the boundary between the core and mantle. Damanveer Grewal, an assistant professor at Yale, stated this represents carbon leaking from the core. The isotopic makeup corresponded to carbonaceous chondrites, defined as carbon-rich meteorites originating in the outer solar system that contain organic compounds. Earlier theories held that observing core carbon isotopes was impossible before this breakthrough.

Timing of carbon arrival explained

Grewal noted there was only one window for these meteorites to become a permanent part of the core during Earth's main assembly. If carbon arrived earlier, collisions would have sent much of it back into space. Later arrival meant the core would already be closed off from external material. This research resolves a longstanding debate about how carbon reached the planet's interior.