Time Capsule Found in Himalayas Offer Insight Into Earth's Past

Saturday - July 29 2023, 17:25 UTC - 1 year ago

Researchers have discovered a 600 million year old time capsule in the Himalayas’ mineral deposits. This finding directly links the two critical events in Earth's history - the Snowball Earth glaciation and the Second Great Oxygenation Event - and can be used to unlock the mysteries of Earth's evolution from unicellular to complex life forms. The study was a joint effort by scientists from the Indian Institute of Science and Niigata University in Japan.

Researchers claim that they have found a time capsule for paleo oceans in the Himalayas’ mineral deposits. A team of scientists from India and Japan, studying the Kumaon region of the Himalayas in the Indian state of Uttarakhand, have found that the mineral deposits - magnesite - located in the area contain water droplets that were deposited some 600 million years ago during the Neoproterozoic era. The researchers say that the preservation of magnesite in this region could only have been possible if impurities like calcium in the Deoban Basin were interrupted for a long period of time, probably due to the freezing of the rivers. Himalayan magnesite is a rare exception from the destruction of the paleo-ocean that occurs through tectonic movements.

One of the critical events in Earth history, the Snowball Earth glaciation, during which most of the planet was covered with thick sheets of ice, was followed by another event. The Second Great Oxygenation Event, during which oxygen level in the Earth’s atmosphere increased manifolds and led to the evolution of complex life forms. This research directly links the two events, given that the deposits the scientists found reveal that sedimentary basins were deprived of calcium for an extended period during the Snowball Earth glaciation, probably due to low riverine input as a product of the changing weathering.

"Minerals precipitated from seawater, however, have the potential to preserve evidence of their paleo-oceans. Magmatic, metamorphic, and hydrothermal fluids are commonly trapped in rock-forming minerals. Still, inclusions of paleo-ocean are rarely known because carbonates, the most common marine precipitate, are mostly too fine-grained, readily recrystallized, and chemically altered," the researchers noted.

"We have found a time capsule for paleo oceans. We don’t know much about past oceans. How different or similar were they compared to present-day oceans? Were they more acidic or basic, nutrient-rich or deficient, warm or cold, and what was their chemical and isotopic composition? Such insights could also provide clues about the Earth’s past climate, and this information can be useful for climate modeling," said Prakash Chandra Arya, first author of the study, in an interview with The Hindu.

The research is a joint effort between researchers from the Indian Institute of Science in Bengaluru and Niigata University in Japan. The study was published in Precambrian Research.

Study abstract: .

The widespread glaciation (∼750–580 Ma) of the late Neoproterozoic Snowball Earth and the subsequent (∼630–551 Ma) oxygenation of the oceans and atmosphere were critical factors in microbial evolution and the following ∼540–520 Ma explosion of complex life forms in the Cambrian. However, the underlying mechanisms that link these processes are still unclear due to poorly preserved fossil records and the tectonic destruction of the paleo-oceans, limiting our understanding of the Neoproterozoic Earth, a key time when unicellular life evolved into complex forms. Droplets of Neoproterozoic oceanwater and freshwater trapped in Himalayan crystalline magnesite (MgCO3) show that sedimentary basins were deprived of calcium for an extended period during the Snowball Earth glaciation, probably due to low riverine input as a product of changing weathering. The succession of these two events (Snowball and following oxygenation) recorded in the ancient Himalayan geological record could be the Rosetta stone that will enable us to unlock the mysteries of Earth’s evolution from a unicellular chemical to a complex, physical and biological Earth.