Skip to main content

Drop of ancient seawater rewrites Earth's history

The remains of a microscopic drop of ancient seawater has assisted in rewriting the history of Earth's evolution when it was used to re-establish the time that plate tectonics started on the planet.
Plate tectonics is Earth's vital -- and unique -- continuous recycling process that directly or indirectly controls almost every function of the planet, including atmospheric conditions, mountain building (forming of continents), natural hazards such as volcanoes and earthquakes, formation of mineral deposits and the maintenance of our oceans. It is the process where the large continental plates of the planet continuously move, and the top layers of the Earth (crust) are recycled into the mantle and replaced by new layers through processes such as volcanic activity.
Where it was previously thought that plate tectonics started about 2.7 billion years ago, a team of international scientists used the microscopic leftovers of a drop of water that was transported into the Earth's deep mantle -- through plate tectonics -- to show that this process started 600 million years before that. An article on their research that proves plate tectonics started on Earth 3.3 billion years ago was published in the high impact academic journal, Nature, on 16 July.
"Plate tectonics constantly recycles the planet's matter, and without it the planet would look like Mars," says Professor Allan Wilson from the Wits School of Geosciences, who was part of the research team.
"Our research showing that plate tectonics started 3.3 billion years ago now coincides with the period that life started on Earth. It tells us where the planet came from and how it evolved."
Earth is the only planet in our solar system that is shaped by plate tectonics and without it the planet would be uninhabitable.
For their research, the team analysed a piece of rock melt, called komatiite -- named after the type occurrence in the Komati river near Barberton in Mpumalanga -- that are the leftovers from the hottest magma ever produced in the first quarter of Earth's existence (the Archaean). While most of the komatiites were obscured by later alteration and exposure to the atmosphere, small droplets of the molten rock were preserved in a mineral called olivine. This allowed the team to study a perfectly preserved piece of ancient lava.
"We examined a piece of melt that was 10 microns (0.01mm) in diameter, and analysed its chemical indicators such as H2O content, chlorine and deuterium/hydrogen ratio, and found that Earth's recycling process started about 600 million years earlier than originally thought," says Wilson. "We found that seawater was transported deep into the mantle and then re-emerged through volcanic plumes from the core-mantle boundary."
The research allows insight into the first stages of plate tectonics and the start of stable continental crust.
"What is exciting is that this discovery comes at the 50th anniversary of the discovery of komatiites in the Barberton Mountain Land by Wits Professors, the brothers Morris and Richard Viljoen," says Wilson.
Story Source:
Materials provided by University of the Witwatersrand. 
Note: Content may be edited.

Comments

Post a Comment

Popular posts from this blog

Dark matter may be older than the Big Bang

Dark matter, which researchers believe make up about 80% of the universe's mass, is one of the most elusive mysteries in modern physics. What exactly it is and how it came to be is a mystery, but a new Johns Hopkins University study now suggests that dark matter may have existed before the Big Bang. The study, published August 7 in  Physical Review Letters , presents a new idea of how dark matter was born and how to identify it with astronomical observations. "The study revealed a new connection between particle physics and astronomy. If dark matter consists of new particles that were born before the Big Bang, they affect the way galaxies are distributed in the sky in a unique way. This connection may be used to reveal their identity and make conclusions about the times before the Big Bang too," says Tommi Tenkanen, a postdoctoral fellow in Physics and Astronomy at the Johns Hopkins University and the study's author. While not much is known about its origins,...
Post a Comment
Read more

Home births as safe as hospital births: International study suggests

A large international study led by McMaster University shows that low risk pregnant women who intend to give birth at home have no increased chance of the baby's perinatal or neonatal death compared to other low risk women who intend to give birth in a hospital. The results have been published by  The Lancet 's  EClinicalMedicine  journal. "More women in well-resourced countries are choosing birth at home, but concerns have persisted about their safety," said Eileen Hutton, professor emeritus of obstetrics and gynecology at McMaster, founding director of the McMaster Midwifery Research Centre and first author of the paper. "This research clearly demonstrates the risk is no different when the birth is intended to be at home or in hospital." The study examined the safety of place of birth by reporting on the risk of death at the time of birth or within the first four weeks, and found no clinically important or statistically different risk between home...
Post a Comment
Read more

GSAT-11 satellite to be launched from French Guiana on Dec 5th

GSAT-11 satellite to be launched from French Guiana on Dec 5th GSAT-11 would be located at 74 East and is the fore-runner in a series of advanced communications satellite with multi-spot beam antenna coverage over Indian mainland and Islands, ISRO said. GSAT-11 is the next generation “high throughput” communication satellite configured around ISRO’s I-6K Bus. (PTI/Representational). Indian space agency ISRO is scheduled to launch GSAT-11, the “heaviest” satellite built by it, on-board Ariane-5 rocket of Arianespace from French Guiana on December 5. Weighing about 5,854 kg, GSAT-11 would play a vital role in providing broadband services across the country, and also provide a platform to demonstrate new generation applications, the Indian Space Research Organisation (ISRO) said. It is the “heaviest” satellite built by ISRO, the space agency said. GSAT-11 is the next generation “high throughput” communication satellite configured around ISRO’s  I-6K Bus, and it...
Post a Comment
Read more