A new study challenges the 'late veneer' theory, suggesting Earth's essential elements may have been present from its formation, not delivered later.
Late veneer theory challenged
A new study challenges the long-held belief that Earth received a late addition of material through meteorites, known as the "late veneer" theory, which has been widely accepted since the 1970s.
Earth's formation and the late veneer
Earth formed about 4.5 billion years ago through a series of meteorite collisions. The late veneer theory proposed that a final wave of meteorite impacts added essential elements to Earth after its core and mantle had formed.
Role of highly siderophile elements
Scientists observed that Earth's mantle contains high concentrations of elements like gold and platinum, which are strongly attracted to iron. These concentrations were thought to require a late addition of material, supporting the idea that life's essential elements like carbon and hydrogen arrived later.
Alternative explanation proposed
A study published in Science Advances suggests that the extreme conditions during Earth's formation could explain these element concentrations without needing a late veneer. This challenges the idea that life's ingredients were delivered later and implies they were present from Earth's early history.
Recreating Earth's formation
Researchers simulated the intense pressure and temperature of Earth's early formation using diamond anvil cells and laser heating. They found that high temperatures during Earth's differentiation affected how elements partitioned between the core and mantle.
Temperature's impact on element distribution
The study shows that under Earth's core formation conditions, highly siderophile elements like gold and iridium had less affinity for iron and more for silicates. This explains their presence in the mantle without requiring a late veneer, offering a new understanding of Earth's early chemical evolution.
