Early Earth Atmosphere More Oxidized Than Previously Thought

[Schneibster]

Scientists have used a novel technique to determine the most likely early Earth atmosphere: making artificial lava and creating zircons, then comparing them with real ones created in early lava flows. Zircons are one of the oldest minerals on Earth, and there are some that date back four billion years, to shortly after the Earth's crust solidified. By repeatedly creating zircons in the manner that they normally are created in lava flows, scientists have duplicated details of their composition that tell them the mixture of gases that must have been dissolved in molten rock extruded from the mantle and outgassed to form the early atmosphere.

While two of the ices, CO2 and water, were prevalent, the other two, methane and ammonia, were likely not very common in the atmosphere. This goes against expectations, and may require changes not only to Earth science, but to theories of the origin and development of the early Solar System. In addition, the famous Miller-Urey experiment is shown to be incorrect; the atmosphere used in the experiment doesn't look very much like the early Earth. So this experiment will need to be redone.

Read all about it. This is groundbreaking, and because of the effect on the Miller-Urey experiment may have wide-reaching implications beyond the obvious.

[Berthold]

However, haven't experiments using other gas mixtures and various kinds of energy input yielded results quite similar to the Miller-Urey experiment, which was just the first of them and remains the most famous?

[Schneibster]

Not with such a highly oxidized atmosphere, AFAIK. Got a link? Because that's what mine says:

For decades, scientists believed that the atmosphere of early Earth was highly reduced, meaning that oxygen was greatly limited. Such oxygen-poor conditions would have resulted in an atmosphere filled with noxious methane, carbon monoxide, hydrogen sulfide, and ammonia. To date, there remain widely held theories and studies of how life on Earth may have been built out of this deadly atmosphere cocktail.

Now, scientists at Rensselaer are turning these atmospheric assumptions on their heads with findings that prove the conditions on early Earth were simply not conducive to the formation of this type of atmosphere, but rather to an atmosphere dominated by the more oxygen-rich compounds found within our current atmosphere — including water, carbon dioxide, and sulfur dioxide.

So give 'em a call, Berthold, and let 'em know they're wrong. I'm sure you know more than they do.

[Azathoth]

How do they explain banded iron formations and detrital pyrite? Then we have this later

Watson thinks the discovery of his group may reinvigorate theories that perhaps those building blocks for life were not created on Earth, but delivered from elsewhere in the galaxy.

I'm expecting serious flaws to be pointed out in their methodology

[Seth]

How do they explain banded iron formations and detrital pyrite? Then we have this later

Watson thinks the discovery of his group may reinvigorate theories that perhaps those building blocks for life were not created on Earth, but delivered from elsewhere in the galaxy.

I'm expecting serious flaws to be pointed out in their methodology

Ah, panspermia...or...wait for it...God!

[Gawdzilla Sama]

Yeah, "god", for when thinking isn't an option.

[Schneibster]

What particularly caught my eye was that they'd used zircons. Zircons are one of the oldest things around. IIRC the age of the Earth's solid crust was first directly determined using zircons.

Is it common to take guesses about what shouldawouldacouldaoughta have happened as more accurate than measurements? Just askin'.

You did see it was published in Nature, right?

[Azathoth]

If they supply a mechanism for the deposition of banded iron formations in an atmosphere that has always been oxidising I will take more notice of their lab tinkerings. Until then I will assume they have made a mistake somewhere along the line

[Azathoth]

You did see it was published in Nature, right?

and that is just an appeal to authority. Do you think nature never publishes anything that is wrong?

[Schneibster]

Hmmmm, over here "famous scholarly journal that does careful peer review" over there "claim by random dude on Internets."

So many difficult decisions. So little time.

[Schneibster]

If they supply a mechanism for the deposition of banded iron formations in an atmosphere that has always been oxidising I will take more notice of their lab tinkerings. Until then I will assume they have made a mistake somewhere along the line

You do realize that they're saying that the lava extruded in the Hadean had lots of oxygen in it, right?

I'll just let you think about the implications of that a little while.

[Azathoth]

Stating that the magmas in the Hadean were more oxygen rich that previously thought is fine it just leads to the formation of different minerals. Making the leap that enough oxygen was released to the atmosphere to make it oxidising is where the problem comes in. It doesn't fit the evidence in the rocks

[Schneibster]

Zircons aren't rocks?

OK.

Where is all this Hadean iron banding, again?

[Azathoth]

Zircons are minerals and as such can only indicate the composition of the magma they crystallised from. They are not indicators of the wider environment. There aren't any Hadean BIFs because the atmosphere was reducing. The iron was in solution. You need a change from a reducing to an oxidising environment for the iron to precipitate. Thanks for supporting my point

[Schneibster]

http://en.wikipedia.org/wiki/Hadean#Atm ... and_oceans

A September 2008 study of zircons found that Australian Hadean rock holds minerals that point to the existence of plate tectonics as early as 4.0 Ga.[8] If this holds true, the previous beliefs about the Hadean period are far from correct. That is, rather than a hot, molten surface and atmosphere full of carbon dioxide, the Earth's surface would be very much like it is today. The action of plate tectonics traps vast amounts of carbon dioxide, thereby eliminating the greenhouse effects and leading to a much cooler surface temperature and the formation of solid rock, and possibly even life.[8]

This is the article for footnote 8.

Two sources say the atmosphere was more like today's. That our prior understanding of the Hadean was all wrong.

I'm finding more. You appear to be the old guard viciously defending the old paradigm and being remorselessly washed away by the rising tide.