oldest rock formation known on Earth tagged posts

Oldest rock on Earth: Acasta River gneiss (stock image). Credit: © Xenomanes / Fotolia

Scientists have found that 4.02-billion-year-old silica-rich felsic rocks from the Acasta River, Canada – the oldest rock formation known on Earth – probably formed at high temperatures and at a surprisingly shallow depth of the planet’s nascent crust. The high temperatures needed to melt the shallow crust were likely caused by a meteorite bombardment around half a billion years after the planet formed. This melted the iron-rich crust and formed the granites we see today. These results are presented for the first time at the Goldschmidt conference in Boston (14 August), following publication in the peer-reviewed journal Nature Geoscience.

The felsic rocks (rocks rich in silica/quartz) found at the Acast...