EARTH

The Largest Magma Chamber

~2.06 to 2.055 billion years ago

Proterozoic · Paleoproterozoic · Rhyacian

In what is now South Africa, a million cubic kilometres of magma lodged in the crust and cooled slowly. As it cooled, its minerals settled out in order of density, layer upon layer, like sediment in still water, building a stack seven kilometres thick and a hundred across; most of it crystallised within a single million years. A few of those layers hold most of the world's platinum, chromium and vanadium.

Why it matters

Nearly every catalytic converter on the planet contains metal from this single body of rock, crystallised while the air was still learning to hold oxygen.

Dating & uncertainty

Uranium-lead dating of zircon puts the whole complex between 2060 and 2055 million years, with the bulk of it inside a single million-year interval. Whether it filled as one great tank or as a stack of sills is argued in print, comment and reply.

Sources

1. Scoates et al. (2021), Journal of Petrology · Dating the Bushveld Complex: timing of crystallization, duration of magmatism, and cooling
2. Mitchell et al. (2021), Journal of Petrology · Comment on Dating the Bushveld Complex
3. Scoates et al. (2021), Journal of Petrology · Reply to comment on Dating the Bushveld Complex

Earth history as one day

13:06:3610 h 53 min before midnight

if Earth’s 4.54 billion years were compressed into a single day