Cosmic dust reveals Earth's ancient atmosphere

Science Daily ^ | 5/11/2016 | Monash University

[JimSEA]

Using the oldest fossil micrometeorites -- space dust -- ever found, Monash University-led research has made a surprising discovery about the chemistry of Earth's atmosphere 2.7 billion years ago.

The findings of a new study published today in the journal Nature -- led by Dr Andrew Tomkins and a team from the School of Earth, Atmosphere and Environment at Monash, along with scientists from the Australian Synchrotron and Imperial College, London -- challenge the accepted view that Earth's ancient atmosphere was oxygen-poor. The findings indicate instead that the ancient Earth's upper atmosphere contained about the same amount of oxygen as today, and that a methane haze layer separated this oxygen-rich upper layer from the oxygen-starved lower atmosphere.

Dr Tomkins explained how the team extracted micrometeorites from samples of ancient limestone collected in the Pilbara region in Western Australia and examined them at the Monash Centre for Electron Microscopy (MCEM) and the Australian Synchrotron.

"Using cutting-edge microscopes we found that most of the micrometeorites had once been particles of metallic iron -- common in meteorites -- that had been turned into iron oxide minerals in the upper atmosphere, indicating higher concentrations of oxygen than expected," Dr Tomkins said.

[SunkenCiv]

Thanks JimSEA.

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[SunkenCiv]

Early Earth keyword, sorted alpha:

• Abiogenesis: The First Frontier [2002]
• Ancient bubbles in Australian rocks show early Earth's air weighed less (trunc) [2016]
• Ancient Rocks Show How Young Earth Avoided Becoming Giant Snowball [2007]
• Calculations favor reducing atmosphere for early earth: Was Miller-Urey experiment correct? [2005]
• Clandestine comets found in main asteroid belt - Earth oceans origin [2006]
• Comet's water 'like that of Earth's oceans' [2011]
• Cosmic dust reveals Earth's ancient atmosphere [2016]
• Cosmic Impacts May Have Seeded Early Earth with Ingredients for Life [2015]
• Did Life Come from Another World?(Long Read) [2005]
• Double Whammy: 2 Meteors Hit Ancient Earth At The Same Time [2015]
• Early Earth Likely Had Continents, Was Habitable, According To New Study [2005]
• Early Earth Was Purple, Study Suggests (Go Vikes!) [2007]
• From Old Vials, New Hints on Origin of Life [2008]
• Is Ice a Catalyst for Life Throughout the Universe? [2008]
• Life-Swapping Scenarios for Earth and Mars [2004]
• Organic-Rich Soup-in-the-Ocean of Early Earth [Miller experiment revisited] [2005]
• Prebiotic Soup--Revisiting the Miller Experiment [biogenesis] [2003]
• Rosetta finds molecular oxygen on comet 67P [2015]
• Rosetta Instrument Reignites Debate on Earth's Oceans [2014]
• Row erupts over 'life-starter' vents [2003]
• Salt of the Early Earth [2005]
• Sea floor records ancient Earth [2007]
• Small Comets and Our Origins [2004]
• So, where did the water on Mars come from? [2004]
• Solar System Ice: Source of Earth's Water [2012]
• "Space rock" reveals life's origins [2008]
• Titanium Paternity Test Fingers Earth as Moon's Sole Parent [2012]
• Volume of world's oldest water estimated [2014]
• We are all made of comet dust [2013]
• Where on Earth has our water come from? [2010]
• Why Didn't Early Earth Freeze? The Mystery Deepens (Another CO2 hypothesis is debunked!) [2010]

[alexander_busek]

O3 is formed out of O2. What would you have O2 formed out of? Windborne rootless plants?

?!

No: In the ozonosphere, three O2 molecules are (temporarily) formed from two O3 molecules. Then, the process is reversed. Thus, atomic oxygen (i.e., single atoms of oxygen) is also present to a certain degree. And don't forget that - compared to ground level - it's a near-vacuum up there. Methane in such miniscule concentrations wouldn't "burn" with a visible flame.

Regards,