Indian scientists discover ancient ocean in Himalayas
A team of scientists from India and Japan has made a remarkable discovery in the Himalayas: traces of an ancient ocean that existed before the Tethys Sea, which separated India from Asia more than 250 million years ago. The researchers found water droplets trapped in mineral deposits dating back approximately 600 million years, and the discovery could provide crucial insights into a significant oxygenation event in Earth's past.
The study, published in the journal Precambrian Research, reveals that these mineral deposits, rich in calcium and magnesium carbonates, are akin to a "time capsule for paleo oceans," according to Prakash Chandra Arya, a Ph.D. student at the Centre for Earth Sciences (CEaS), IISc, and the study's lead author. The deposits originated from precipitation from ancient ocean water, rather than from other sources such as submarine volcanic activity.
The researchers conducted their study across a vast stretch of the western Kumaon Himalayas, from Amritpur to the Milam glacier and Dehradun to the Gangotri glacier region. Extensive laboratory analysis confirmed that the deposits contained signatures of both ocean and freshwater, indicating a chain-reaction arising from a series of complex geological processes that swept the earth hundreds of million years ago, triggering epochal changes.
One of these changes was the Snowball Earth glaciation, when the entire globe was enveloped by a kilometre-thick ice cover 750-580 million years ago. This was followed by the Second Great Oxygenation Event, which led to a surge in atmospheric oxygen levels and the evolution of complex life forms. However, the connection between these events has remained elusive due to the scarcity of well-preserved fossils and the disappearance of ancient oceans.
The newly discovered marine rocks in the Himalayas could provide some answers. The team's findings suggest that during the Snowball Earth glaciation, sedimentary basins experienced a prolonged calcium deficiency, likely due to reduced riverine input. This lack of calcium led to an increase in magnesium levels, with the resulting magnesium deposits trapping ancient ocean water as they crystallised.
This calcium deprivation may have also resulted in a nutrient deficiency, creating favourable conditions for slow-growing photosynthetic cyanobacteria. These organisms could have begun releasing more oxygen into the atmosphere, contributing to the Second Great Oxygenation Event.
The discovery of 600 million year old ocean water in the Himalayas is not only a testament to the geological history of India and Asia, but also a valuable source of information for understanding the Earth's past climate and evolution of life. As Sajeev Krishnan, team leader and professor at CEaS, IISc, told DH, "Until now no traces of ocean water from the 600-million year old ocean have ever been found. We derived the age of the water from the age of the mineral-bearing rocks that entrapped them. Our studies show that those early-earth water droplets are comparable to present ocean water."
Source:
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