Hadean Protocrust:
A new international study led by Macquarie University, Australia, suggests that the chemical signatures attributed to plate tectonics were already present in the Hadean protocrust.
- The Hadean protocrust refers to the earliest known crust of the Earth—its outermost solid layer—that formed during the Hadean aeon, the planet’s first geologic era, which began around 6 billion years ago.
- This period is named after ‘Hades’, the Greek god of the underworld, due to the extremely hot, hostile, and unstable conditions that prevailed on early Earth.
- The Earth, within its first 200 million years, had a surface that was partially molten, with widespread volcanic activity and constant meteorite bombardment from space.
- During this time, the magma ocean—a vast reservoir of molten rock covering Earth’s surface—began to cool gradually.
- As the surface cooled, early fragments of solid crust began to form. These fragments were not stable and often broke off, while new layers solidified, creating a flaky, unstable crustal layer.
- Some thicker segments of this primitive crust eventually consolidated into the first proto-continents, floating on the underlying asthenospheric mantle—a semi-fluid layer extending up to 400 km beneath the surface.
- As these crustal plates drifted across the mantle, they began to interact in various ways: colliding, sliding past, or subducting (diving under) one another.
- These early plate movements laid the foundation for plate tectonics, a key process in shaping the Earth’s geological features.
- Over time, these interactions left distinct chemical signatures in the Earth’s crust, enabling scientists to reconstruct the history of tectonic activity.
