Unearthing Ancient Ocean Secrets – Pioneering Finds from the Himalayas Illuminate Earth’s History

Scientists from the Indian Institute of Science and Niigata University have unearthed preserved primordial ocean water within mineral formations in the Himalayas, traced back to nearly 600 million years ago. This groundbreaking discovery casts new light on the major oxygenation phase of the Earth and the epoch of global glaciation known as the Snowball Earth, contributing valuable insights into the development of complex life forms and the chemical status of early oceans.

In the lofty heights of the Himalayas, investigators from the Indian Institute of Science (IISc) and Niigata University, Japan, have detected water droplets, likely originating from an ocean from 600 million years ago, sealed within mineral formations. An analysis of these formations, which include both calcium and magnesium carbonates, enabled the team to put forward a plausible theory for events that may have contributed to a significant oxygenation phase in the Earth’s past.

“We’ve discovered a historical repository for ancient oceans,” declares Prakash Chandra Arya, a Ph.D. candidate at the Centre for Earth Sciences (CEaS) at IISc, and lead author of the study, published in Precambrian Research.

Researchers theorize that between 700 and 500 million years ago, thick layers of ice encapsulated the Earth for an extended period, a time referred to as the Snowball Earth glaciation, one of the most significant glacial events in the Earth’s history. What followed this period was a rise in the Earth’s atmospheric oxygen content, known as the Second Great Oxygenation Event, which eventually facilitated the evolution of complex life forms. Due to the scarcity of well-preserved fossils and the disappearance of all ancient oceans from the Earth’s history, the links between these events remain somewhat obscure. However, the exposure of these marine rocks in the Himalayas may yield some answers.

“Our understanding of past oceans is limited,” states Prakash. “How did they compare to our current oceans? Were they more acidic or alkaline, abundant in nutrients or lacking, warm or cold, and what were their chemical and isotopic characteristics?” He adds that these insights could offer clues about the Earth’s historical climate, which could aid in climate modeling.

The formations discovered by the team date back to around the time of the Snowball Earth glaciation and demonstrate that the sedimentary basins were calcium-deficient for a long period, likely due to minimal river input. “During this time, the oceans were stagnant, without calcium influx. As more calcium precipitates in the absence of input or flow, the quantity of magnesium rises,” Sajeev Krishnan, a Professor at CEaS and co-author of the study, explains. The researchers propose that the magnesium formations that developed during this time encapsulated ancient ocean water within their cavities as they crystallized.

The lack of calcium also likely led to a nutrient shortage, creating ideal conditions for the slow growth of photosynthetic cyanobacteria, which may have started releasing more oxygen into the atmosphere. “An increase in atmospheric oxygen typically triggers biological evolution,” notes Prakash.

The researchers ventured across a wide stretch of the western Kumaon Himalayas, spanning from Amritpur to the Milam glacier, and Dehradun to the Gangotri glacier region, in search of these deposits. Extensive laboratory testing confirmed that the deposits originated from precipitation of ancient ocean water and not from other sources such as Earth’s interior or submarine volcanic activity.

The team believes these deposits hold key information about early oceanic conditions including pH, chemistry, and isotopic composition, which till now, were only hypothesized or modeled. This information can help address queries related to the evolution of the Earth’s oceans, and possibly even life itself.

Reference: “Himalayan magnesite records abrupt cyanobacterial growth that plausibly triggered the Neoproterozoic Oxygenation Event” by Prakash Chandra Arya, Claude Nambaje, S. Kiran, M. Satish-Kumar and K. Sajeev, 17 July 2023, Precambrian Research.
DOI: 10.1016/j.precamres.2023.107129

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More about Ancient Ocean Discovery

• Indian Institute of Science
• Niigata University
• Precambrian Research
• Snowball Earth
• Great Oxygenation Event
• Understanding Cyanobacteria
• Information on Magnesite