Why is it in the News?

Exploring ancient cratons such as the Singhbhum Craton in India, alongside similar formations in South Africa and Australia, provides unparalleled insights into the early stages of our planet's development, reaching back approximately 3.5 billion years.

What is Singhbhum Craton?

• The Singhbhum Craton encompasses a vast expanse of rugged terrain, primarily spanning regions in Jharkhand and Odisha, situated between the Chhota Nagpur plateau and the Eastern Ghats.
• Dating back approximately 3.5 billion years, this ancient segment of the Earth's crust offers valuable insights into early geological processes.
• Its oldest rock formations consist predominantly of volcanic and sedimentary rocks, referred to as greenstone successions.
  • Greenstones are characterised by submarine volcanic rocks with minor sedimentary components.
• Geologically akin to greenstone belts in South Africa's Barberton and Nondweni regions and the Pilbara Craton in Western Australia, these areas experienced extensive submarine mafic volcanic activity, rich in magnesium oxide, between 3.5 and 3.3 billion years ago, with preserved features like pillowed lava and komatiites.

Significance:

• The Singhbhum Craton sheds light on early tectonic activities during the Archaean era, enhancing our understanding of the Earth's formative stages.
• Its distinctive geological characteristics, particularly the presence of greenstone belts, yield invaluable data on surface and atmospheric processes crucial for theorising about early habitable conditions and the emergence of life on Earth.

What are Cratons?

• A craton is a stable and ancient part of Earth's lithosphere that has experienced long-term tectonic and geomorphic stability.
• It is considered to be the nucleus of a continent and is characterised by its thick and cold lithosphere.
• Cratons can undergo destruction, which is defined as a geological process resulting in the loss of craton stability due to changes in its physical and chemical properties.
• The mechanisms responsible for craton destruction include oceanic plate subduction, rollback and retreat of subducting plates, stagnation and dehydration of subducting plates in the mantle transition zone, melting of the mantle caused by dehydration of stagnant slabs, non-steady flow in the upper mantle induced by melting, and changes like the lithospheric mantle.
• Craton destruction can lead to crustal thinning, surface uplift, and the concentration of mineral deposits.