The discovery of living stromatolites on Sheybarah Island in Saudi Arabia is a big step forward in understanding Earth’s ancient history and the development of life.
What are Stromatolites?
Stromatolites are layers of limestone formed mainly by blue-green algae growth. They have thin, alternating light and dark layers and come in flat, hummocky, or dome shapes.
- Origins: Stromatolites were prevalent during the Precambrian era, over 542 million years ago.
- While most stromatolites are marine, some dating back more than 2 ½ billion years from Proterozoic strata are believed to have formed in intertidal zones, freshwater ponds, and lakes.
- Formation: Stromatolite formation initiates with the growth of cyanobacteria on surfaces like rocks or sediment.
- As these microorganisms proliferate, they capture and bind sediment particles, accumulating organic material and minerals in layers.
- Gradually, these layers accumulate, resulting in the formation of characteristic dome-shaped or columnar structures.
- Habitation: Stromatolites flourish most in Shark Bay, Western Australia, where high salt levels caused by evaporation discourage snails and other organisms from eating the algae, aiding their growth.
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Great Oxygenation Event
Around 2.4 billion years ago, cyanobacteria emitted oxygen into Earth’s oceans, enriching them with oxygen. Over time, the oxygen began escaping into the atmosphere, interacting with methane.
- As oxygen release increased, methane was gradually displaced, and oxygen became a predominant component of the atmosphere.
- This significant transition in Earth’s atmospheric composition is known as the Great Oxidation Event.
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- Role of Stromatolites: Stromatolites played a key role in the Great Oxygenation Event, significantly altering the Earth’s atmosphere by introducing oxygen.
- This oxygen initially eliminated competition for stromatolites, allowing them to dominate the Archean and early Proterozoic environments.
Significance of Stromatolites
- Insights into Early Life: Stromatolites offer direct evidence of ancient microbial communities, shedding light on Earth’s early biosphere.
- Environmental Reconstruction: They assist scientists in reconstructing past climates, ocean chemistry, and atmospheric conditions.
- Astrobiological Significance: The study of ancient stromatolites contributes to the search for potential life on other planets, such as Mars.
Stromatolite Deposits in India
- Vindhyan Supergroup (Central India): Rich in stromatolites, with some formations dating back 2.5 billion years.
- Bhima Basin (Karnataka): Various stromatolite formations providing insights into ancient ecosystems.
- Additional Sites: Rajasthan, Chhattisgarh, and the Himalayas also feature smaller stromatolite deposits.
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About Sheybarah Island
- Environment of Sheybarah Island: Sheybarah Island features an intertidal to shallow subtidal environment.
- It is characterized by frequent shifts between wet and dry conditions, wide temperature fluctuations ranging from 8°C to over 48°C, and nutrient-poor conditions similar to those in the Bahamas.
- Diversity: The Sheybarah Island field comprises numerous stromatolites, ranging from fully developed textbook specimens to flat structures with minimal relief, potentially indicating early stages of formation.
Shark Bay
- About: Shark Bay, is a designated UNESCO World Heritage Site situated in the Gascoyne region of Western Australia.
- Natural Features: It has three exceptional natural features:
- It has vast sea-grass beds, which are the largest and richest in the world
- It has large dugong (‘sea cow’) population
- It has stromatolites (colonies of algae which form hard, dome-shaped deposits and are among the oldest forms of life on Earth).
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6 Jun 2024
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