Remixed mantle suggests early start of plate tectonics

Related Articles

Related Articles

New Curtin University research on the remixing of Earth’s stratified deep interior suggests that global plate tectonic processes, which played a pivotal role in the existence of life on Earth, started to operate at least 3.2 billion years ago.

Published in Nature’s Scientific Reports, researchers from Curtin University’s Earth Dynamics Research Group re-analysed global data to detect sudden changes in the chemical characteristics of basalt and komatiite lava rocks, believed to have been derived from Earth’s upper and lower mantle layers and erupted to the surface between two and four billion years ago.

Lead researcher PhD Candidate Mr Hamed Gamal El Dien, from Curtin’s School of Earth and Planetary Sciences, said there was much scientific debate over the exact start date of plate tectonics on Earth.

 

“Some scientists believe plate tectonics only began to operate from around 800 million years ago, whereas others think it could go as far back as four billion years ago, soon after the formation of our planet,” Mr Gamal El Dien said.

“So far nearly all the evidence used in this debate came from scarcely preserved surface geological proxies, and little attention has been paid to the record kept by Earth’s deep mantle – this is where our research comes in.

“For the first time, we were able to demonstrate that a significant shift in mantle composition (or a major mantle remixing) started around 3.2 billion years ago, indicating a global recycling of the planet’s crustal materials back in to its mantle layer, which we believe shows the start of global plate tectonic activity.”

During the earliest stages of Earth’s planetary differentiation, the planet was divided into three main layers: the core, the mantle and the crust. Scientists believe there would have been very little remixing between the lighter crust and the much denser mantle, until the onset of plate tectonics.

However through the ongoing process of subduction, some lighter crustal materials are carried back into the denser deep Earth and remixed with the mantle. The question the researchers then asked was, when did this global and whole-mantle remixing process start?

“Keeping the basic process of subduction in mind, we hypothesise that ancient rock samples found on the crust, that are ultimately sourced from the deep mantle, should show evidence of the first major ‘stirring up’ in the mantle layer, marking the start of plate subduction as a vital component of plate tectonic processes,” Mr Gamal El Dien said.

To complete this research, the team looked at the time variation of the isotopic and chemical composition of approximately 6,000 mantle-derived basaltic and komatiitic lava rocks, dated to be between two and four billion years old.

Research co-author John Curtin Distinguished Professor and Australian Laureate Fellow Professor Zheng-Xiang Li, head of the Earth Dynamics Research Group, said the research is highly significant in understanding the dynamic evolution of our planet.

“Plate tectonic activity on the planet is responsible for the formation of mineral and energy resources. It also plays a vital role for the very existence of mankind. Plate tectonics are found uniquely operative on Earth, the only known habitable planet,” Professor Li said.

“Through our retrospective analysis of mantle-derived samples, we discovered that after the initial chemical stratification and formation of a hard shell in the first billion years of Earth’s 4.5 billion year history, there was indeed a major chemical ‘stir up’ some 3.2 billion years ago.

“We take this ‘stir up’ as the first direct evidence from deep Earth that plate tectonics started over 3 billion years ago, leading to a step-change in mantle composition, followed by the oxygenation of our atmosphere and the evolution of life.”

CURTIN UNIVERSITY

Header Image Credit : Professor Zheng-Xiang Li

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Ancient Mosaic Criticises Christianity

An ancient mosaic from a 4th-century house in the centre of the ancient city of Paphos in Cyprus, was a 'pictorial' criticism of Christianity according to experts.

Geoscience: Cosmic Diamonds Formed During Gigantic Planetary Collisions

It is estimated that over 10 million asteroids are circling the Earth in the asteroid belt. They are relics from the early days of our solar system, when our planets formed out of a large cloud of gas and dust rotating around the sun.

Vettuvan Koil – The Temple of the Slayer

Vettuvan Koil is a rock-cut temple, located in Kalugumalai, a panchayat town on the ancient trade routes from Kovilpatti to courtallam, in the southern Indian state of Tamil Nadu.

The Testimony of Trees: How Volcanic Eruptions Shaped 2000 Years of World History

Researchers have shown that over the past two thousand years, volcanoes have played a larger role in natural temperature variability than previously thought, and their climatic effects may have contributed to past societal and economic change.

Sentinels of Ocean Acidification Impacts Survived Earth’s Last Mass Extinction

Two groups of tiny, delicate marine organisms, sea butterflies and sea angels, were found to be surprisingly resilient--having survived dramatic global climate change and Earth's most recent mass extinction event 66 million years ago.

The Venerable Ensign Wasp, Killing Cockroaches For 25 million Years

An Oregon State University study has identified four new species of parasitic, cockroach-killing ensign wasps that became encased in tree resin 25 million years ago and were preserved as the resin fossilized into amber.

Modern Humans Reached Westernmost Europe 5,000 Years Earlier Than Previously Known

Modern humans arrived in the westernmost part of Europe 41,000 - 38,000 years ago, about 5,000 years earlier than previously known, according to Jonathan Haws, Ph.D., professor and chair of the Department of Anthropology at the University of Louisville, and an international team of researchers.

Akrotiri – The Ancient Town Buried by a Volcano

Akrotiri is an archaeological site and a Cycladic Bronze Age town, located on the Greek island of Santorini (Thera) near the present-day village of Akrotiri (for which the prehistoric site is named).

Popular stories

The Secret Hellfire Club and the Hellfire Caves

The Hellfire Club was an exclusive membership-based organisation for high-society rakes, that was first founded in London in 1718, by Philip, Duke of Wharton, and several of society's elites.

Port Royal – The Sodom of the New World

Port Royal, originally named Cagway was an English harbour town and base of operations for buccaneers and privateers (pirates) until the great earthquake of 1692.

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.

Did Corn Fuel Cahokia’s Rise?

A new study suggests that corn was the staple subsistence crop that allowed the pre-Columbian city of Cahokia to rise to prominence and flourish for nearly 300 years.