Stromatolites

Prelims – General issues on Environmental ecology, Bio-diversity and Climate Change.

Why in news?

Recently, 600-million-year-old stromatolite outcrop has been discovered in Chambaghat, Solan district, Himachal Pradesh.

• Stromatolites – They are reef-like bio sedimentary structures formed by cyanobacteria (blue-green algae) in ancient shallow seas.

• Time period – It dates from 3.6 billion years old (Australia) to 600 million years old (recent Himalayan discovery).
• Distinction from fossils – If original organism is preserved, it's technically a fossil; if only the mineralised structure (calcium carbonate precipitates) is preserved, it's a biosedimentary structure.

Recent Discovery in the Himalayas

• Location – Pine-clad ridges of Chambaghat in Solan district, Himachal Pradesh.
• Age – 600 million years old.
• It is found at 5,000-6,000 feet above sea level in entire hill covered with stromatolites, not just isolated samples.
• Younger stromatolites – This is the youngest stromatolites in India.

Oldest stromatolites are found in Dharwad in Karnataka, which are at least 2,500 million years old.

• Geological significance – It is part of the Krol Group of sedimentary rocks that is formed in shallow marine environment of the ancient Tethys Sea.

• It helps to reconstruct the theory of a vanished Tethys Sea in the Himalayan region.
• These structures indicate the shallow marine conditions that once existed before the Indian plate collided with Eurasian plate.
• Historical significance – Earth’s atmosphere doesn’t contain oxygen when it is formed and it is composed of carbon dioxide, methane, and water vapor.

• Oxygen production – Cyanobacteria in stromatolites began producing oxygen through photosynthesis around 3.5 billion years ago.
• This contributed to the Great Oxygenation Event, making Earth habitable for complex life.

Great oxidation event occurred around 2.4 billion years ago, transforming Earth's atmosphere and enabling multicellular life.

• Threat – Risk of permanent loss due to development and natural processes such as mining activities, construction and erosion.

Reference

Indian Express| 600-million-year-old stromatolites found in Himalayas