Scientists have long believed that lava erupted from certain
oceanic volcanoes contains materials from the early Earth’s crust. But decisive
evidence for this phenomenon has proven elusive. New research from a team
including Carnegie’s Erik Hauri demonstrates that oceanic volcanic rocks
contain samples of recycled crust dating back to the Archean era 2.5 billion
years ago. Their work is published in Nature.
Oceanic crust sinks into the Earth’s mantle at so-called
subduction zones, where two plates come together. Much of what happens to the
crust during this journey is unknown. Model-dependent studies for how long
subducted material can exist in the mantle are uncertain and evidence of very
old crust returning to Earth’s surface via upwellings of magma has not been
found until now.