In a groundbreaking discovery, scientists from the Indian Institute of Science (IISc) in Bengaluru, in collaboration with Niigata University in Japan, have uncovered remnants of an ancient ocean within the Himalayas. The discovery was made across the expansive stretch of the western Kumaon Himalayas, encompassing regions from Amritpur to the Milam glacier and Dehradun to the Gangotri glacier.
The team identified droplets of water encapsulated within mineral deposits, dating back an estimated 600 million years. These deposits, rich in calcium and magnesium carbonates, have been likened to a “time capsule for paleo oceans” by lead author Prakash Chandra Arya, a Ph.D. student at the Centre for Earth Sciences (CEaS), IISc. The deposits are believed to have originated from precipitation of ancient ocean water.
During the Snowball Earth glaciation, a prolonged period of global glaciation that occurred between 700 and 500 million years ago, the Earth experienced significant changes. Post this event, the Second Great Oxygenation Event ensued, marking a major surge in atmospheric oxygen levels and the evolution of complex life forms. However, the precise connection between these events has largely remained obscure due to the scarcity of well-preserved fossils and the disappearance of ancient oceans.
The recent discovery of marine rocks in the Himalayas could potentially offer some answers to these longstanding questions. The team’s findings indicate that during the Snowball Earth glaciation, sedimentary basins experienced an extended calcium deficiency, possibly due to a decrease in riverine input. The subsequent increase in magnesium levels led to the crystallization of the magnesium deposits, effectively trapping ancient ocean water.
This shortage of calcium might also have induced a nutrient deficiency, creating an optimal environment for slow-growing photosynthetic cyanobacteria. These organisms could have subsequently begun releasing more oxygen into the atmosphere, thereby potentially contributing to the Second Great Oxygenation Event.
The researchers utilized extensive laboratory analysis to confirm that the discovered deposits originated from precipitation from ancient ocean water, as opposed to other potential sources such as submarine volcanic activity. The elucidation of the chemical and isotopic composition of ancient oceans from these findings could provide invaluable information for climate modeling, thereby offering deeper insights into the evolution of oceans and life on Earth.