London Daily

Focus on the big picture.

Where Did Earth's Oxygen Come From? Scientists Hint At An Unexpected Source

Where Did Earth's Oxygen Come From? Scientists Hint At An Unexpected Source

So, how did Earths atmosphere become oxygenated?

The amount of oxygen in the Earth's atmosphere makes it a habitable planet.

Twenty-one per cent of the atmosphere consists of this life-giving element. But in the deep past — as far back as the Neoarchean era 2.8 to 2.5 billion years ago — this oxygen was almost absent.

So, how did Earth's atmosphere become oxygenated?

Our research, published in Nature Geoscience, adds a tantalizing new possibility: that at least some of the Earth's early oxygen came from a tectonic source via the movement and destruction of the Earth's crust.


The Archean Earth


The Archean eon represents one third of our planet's history, from 2.5 billion years ago to four billion years ago.

This alien Earth was a water-world, covered in green oceans, shrouded in a methane haze and completely lacking multi-cellular life. Another alien aspect of this world was the nature of its tectonic activity.

On modern Earth, the dominant tectonic activity is called plate tectonics, where oceanic crust — the outermost layer of the Earth under the oceans — sinks into the Earth's mantle (the area between the Earth's crust and its core) at points of convergence called subduction zones. However, there is considerable debate over whether plate tectonics operated back in the Archean era.

One feature of modern subduction zones is their association with oxidized magmas. These magmas are formed when oxidized sediments and bottom waters — cold, dense water near the ocean floor — are introduced into the Earth's mantle. This produces magmas with high oxygen and water contents.

Our research aimed to test whether the absence of oxidized materials in Archean bottom waters and sediments could prevent the formation of oxidized magmas. The identification of such magmas in Neoarchean magmatic rocks could provide evidence that subduction and plate tectonics occurred 2.7 billion years ago.


The experiment


We collected samples of 2750- to 2670-million-year-old granitoid rocks from across the Abitibi-Wawa subprovince of the Superior Province — the largest preserved Archean continent stretching over 2000 km from Winnipeg, Manitoba to far-eastern Quebec. This allowed us to investigate the level of oxidation of magmas generated across the Neoarchean era.

The 2750- to 2670-million-year-old granitoid rocks collected from the largest preserved Archean continent may help reveal the origin story of the Earth's oxygen.(Dylan McKevitt), Author provided


Measuring the oxidation-state of these magmatic rocks — formed through the cooling and crystalization of magma or lava — is challenging. Post-crystallization events may have modified these rocks through later deformation, burial or heating.

So, we decided to look at the mineral apatite which is present in the zircon crystals in these rocks. Zircon crystals can withstand the intense temperatures and pressures of the post-crystallization events. They retain clues about the environments in which they were originally formed and provide precise ages for the rocks themselves.

Small apatite crystals that are less than 30 microns wide — the size of a human skin cell — are trapped in the zircon crystals. They contain sulfur. By measuring the amount of sulfur in apatite, we can establish whether the apatite grew from an oxidized magma.

Map of the Superior Province that stretches from central Manitoba to eastern Quebec in Canada.(Xuyang Meng), Author provided


We were able to successfully measure the oxygen fugacity of the original Archean magma — which is essentially the amount of free oxygen in it — using a specialized technique called X-ray Absorption Near Edge Structure Spectroscopy (S-XANES) at the Advanced Photon Source synchrotron at Argonne National Laboratory in Illinois.


Creating oxygen from water?


We found that the magma sulfur content, which was initially around zero, increased to 2000 parts per million around 2705 million years. This indicated the magmas had become more sulfur-rich. Additionally, the predominance of S6+ — a type of sulfer ion — in the apatite suggested that the sulfur was from an oxidized source, matching the data from the host zircon crystals.

These new findings indicate that oxidized magmas did form in the Neoarchean era 2.7 billion years ago. The data show that the lack of dissolved oxygen in the Archean ocean reservoirs did not prevent the formation of sulfur-rich, oxidized magmas in the subduction zones. The oxygen in these magmas must have come from another source, and was ultimately released into the atmosphere during volcanic eruptions.

We found that the occurrence of these oxidized magmas correlates with major gold mineralization events in the Superior Province and Yilgarn Craton (Western Australia), demonstrating a connection between these oxygen-rich sources and global world-class ore deposit formation.

The implications of these oxidized magmas go beyond the understanding of early Earth geodynamics. Previously, it was thought unlikely that Archean magmas could be oxidized, when the ocean water and ocean floor rocks or sediments were not.

While the exact mechanism is unclear, the occurrence of these magmas suggests that the process of subduction, where ocean water is taken hundreds of kilometres into our planet, generates free oxygen. This then oxidizes the overlying mantle.

Our study shows that Archean subduction could have been a vital, unforeseen factor in the oxygenation of the Earth, the early whiffs of oxygen 2.7 billion years ago and also the Great Oxidation Event, which marked an increase in atmospheric oxygen by two per cent 2.45 to 2.32 billion years ago.

As far as we know, the Earth is the only place in the solar system — past or present — with plate tectonics and active subduction. This suggests that this study could partly explain the lack of oxygen and, ultimately, life on the other rocky planets in the future as well.The Conversation

Comments

Oh ya 2 year ago
Well if you go back to grade 7 you might remember that plants take in carbon dioxide (yes from cars and cow farts and you ) and expel oxygen that we need to live. Now goverments and countries are trying to eliminate carbon dioxide along with the clot shot to de populate the world except for the ones like devil gates, and the rest of the so called elite. Look up food processing plant fires
Brad 2 year ago
Unbelievable how ignorant these scientists are. Read your bible. Who created all the species.
Sorry fools no such thing as Darwinism.
If Ape turned into man Apes would no longer be here.

1. There are 1,000 plus types of rice. (Creator)
2. 1,000s of types of potato's (creator)

Its all in the bible. Follow the 10 commandments and God will show you but if not he will not.

Newsletter

Related Articles

0:00
0:00
Close
South Korea's Brief Declaration of Martial Law
Unidentified Drones Spotted Over UK Airbases
Israel Offers $5 Million for Each Gaza Hostage Freed
"We Need A British Trump"- Former Prime Minister Elizabeth Truss
Make Orwell fiction again
CIA Official Arrested for Leaking Intelligence on Israel-Iran Conflict
Special counsel Jack Smith asks the court to dismiss his appeal regarding Trump in the Mar-a-Lago classified documents case.
BORIS: UK May Deploy Troops If Trump Cuts Support to Ukraine
Trump Administration Taking Shape: No Invitations Issued to Nikki Haley or Mike Pompeo
Iranian Man Charged in Plot to Assassinate Donald Trump
£3 Billion of British Taxpayer Money Spent by UK Government on Hotel Costs for Migrants
Unlike the shock and profound sadness at 10 Downing Street, British citizens assembled for an impressive rally backing the elected President of the United States, Donald Trump.
Elon Musk Predicts Justin Trudeau's Electoral Defeat
Here's why: Scott Presley convinced swing voters in Pennsylvania with a clear and direct question.
Royal Estates Earning Millions from Public Services and Charities
Siemens Acquires Altair Engineering in $10.6 Billion Deal
The man who got hit by a bus and immediately went back to the pub is strong! Beer is very important.
Donald Trump files $10 billion lawsuit against CBS News, accusing them of 'deceptively doctoring' Kamala Harris' '60 Minutes' interview
Formal Address for Meghan Markle at Invictus Games
Understanding the US Electoral College System
Apple Launches AI Features on Select iPhones
JP Morgan Sued Customers Over Viral Cheque Fraud Scheme
King Charles to Continue Global Tours Despite Cancer Diagnosis
Venice Extends Tourist Entry Fee Program to 2025
Tommy Robinson Charged Under Terrorism Act for Phone Offence
Plans to Increase Employers' National Insurance Announced
Washington Post Editor-at-Large Robert Kagan has RESIGNED after owner Jeff Bezos BARRED the endorsement of Kamala Harris.
Massive Theft of Artisan Cheddar from Neal’s Yard Dairy
US Man Charged with Murder of Co-Worker over Breaks
Carbon Monoxide Incident Claims Lives at UK Care Home
Birmingham Airport Evacuated Due to Suspicious Vehicle
Former US President Barack Obama raps the lyrics to Eminem's ‘Lose Yourself’ after the rapper introduces him at a Kamala Harris rally in Detroit
KYIV URGES NORTH KOREAN TROOPS IN UKRAINE TO SURRENDER
Ofcom Identifies Link Between Social Media Posts and UK Unrest
Russian Boxer Receives Lifetime Ban for Illegal Move in Boxing Debut
Biden Labels Trump a Threat to Democracy
McDonald's Linked to E. coli Outbreak Leading to One Death
Teacher Enoch Burke arrested at Wilson’s Hospital School in Ireland after refusing to endorse and affirm transgender ideology.
FBI Investigates Leak of US Intelligence on Israeli Strike Plans
Israeli Airstrike Targets Hezbollah's Financial Resources
China’s Baidu is revolutionizing transportation with its robotaxi service
Angela Rayner Secures Permanent Seat on UK National Security Council
Russian Ambassador Claims UK's Proxy War in Ukraine
Doctor Advocates for Assisted Dying Law Reform
Ruth Davis Appointed as UK’s First Nature Envoy
Pressure Mounts on Starmer to Discuss Reparations at Commonwealth Summit
James Cleverly’s Costly In-Flight Catering for Government Trips
AI Regulation Takes Center Stage in 2024 US Presidential Campaign
NASA Study Explores Potential Microbial Life Beneath Mars' Ice
Cats: The Liquid-Like Pets
×