Rock weathering may have led to 'Snowball Earth'

Dec 17, 2013 by Bob Yirka report
Comparison of unweathered (left) and weathered Ordovician limestone at a roadcut on the State College Bypass, U.S. Route 322. Credit: Wikipedia.

(Phys.org) —A team of researchers conducting a field study in the Mackenzie Mountains in northwest Canada is suggesting rock weathering almost a billion years ago, may have led to the entire planet being encased in ice for 55 million years. In their paper published in Proceedings of the National Academy of Sciences, the multi-national team describes their field study and subsequent analysis of rock samples they retrieved and how doing so led to what they believe is an explanation of one of the most dramatic instances of climate change on record.

Scientists believe that the Earth has experienced many episodes of global glaciation—where the entire planet is covered in ice, resulting in what is loosely termed, a "Snowball Earth." To better understand heading into the future, scientists look to the past. In this latest effort, the research team looked at an event known as the Sturtian glaciation—after a billion years with no ice on the planet at all, suddenly, the Earth was covered with the stuff for 55 million years. Until now, why this happened has been a mystery.

To find out more, the team traveled to the Mackenzie Mountains—a part of the planet that has been found to be useful for plotting the past due to its glacial history. The researchers collected sedimentary rocks left by glacial movement along with rock samples found above and below them.

The rock samples were all taken back to the lab where the researchers tested them for osmium and rhenium levels—the latter breaks down to the former over time, offering a way to determine the age of the rocks. Using this technique, the researchers were able to conclude that the Sturtian lasted for approximately 55 million years. The team also tested the for isotopes of the same two elements and that led to the discovery that had been sequestered in them. This led to the development of a theory that suggests that volcanic activity prior to the Sturtian also led to the absorption of so much carbon dioxide (weathering opens up rock causing it to be more absorbent) from the atmosphere that the planet cooled until it eventually became a Snowball Earth.

Moving forward, the question of whether the Sturtian was truly one long event, or if it was actually a time of many glacial increases and retreats will be further studied to better understand the mechanism behind such global extremes.

Explore further: Meteorite study suggests Mars' ancient atmosphere may be locked in its rocky terrain

More information: Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth, PNAS, Published online before print December 16, 2013, DOI: 10.1073/pnas.1317266110

Abstract
After nearly a billion years with no evidence for glaciation, ice advanced to equatorial latitudes at least twice between 717 and 635 Mya. Although the initiation mechanism of these Neoproterozoic Snowball Earth events has remained a mystery, the broad synchronicity of rifting of the supercontinent Rodinia, the emplacement of large igneous provinces at low latitude, and the onset of the Sturtian glaciation has suggested a tectonic forcing. We present unique Re-Os geochronology and high-resolution Os and Sr isotope profiles bracketing Sturtian-age glacial deposits of the Rapitan Group in northwest Canada. Coupled with existing U-Pb dates, the postglacial Re-Os date of 662.4 ± 3.9 Mya represents direct geochronological constraints for both the onset and demise of a Cryogenian glaciation from the same continental margin and suggests a 55-My duration of the Sturtian glacial epoch. The Os and Sr isotope data allow us to assess the relative weathering input of old radiogenic crust and more juvenile, mantle-derived substrate. The preglacial isotopic signals are consistent with an enhanced contribution of juvenile material to the oceans and glacial initiation through enhanced global weatherability. In contrast, postglacial strata feature radiogenic Os and Sr isotope compositions indicative of extensive glacial scouring of the continents and intense silicate weathering in a post–Snowball Earth hothouse.

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User comments : 15

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MR166
2.1 / 5 (18) Dec 17, 2013
Now I have heard it all, the rocks ate my CO2 and caused the earth to freeze.

I have some news for all of you AGW worshipers - the earth, or Gaia as the true believers like to call it, is close to a historical low point for the percentage of CO2 in the air.

There I have said it, The King Has No Clothes!

If you really want to save mankind perhaps you should go back to worshiping the sun for that is what controls the temperatures on earth.

Maggnus
3.7 / 5 (15) Dec 17, 2013
Now I have heard it all, the rocks ate my CO2 and caused the earth to freeze.


Now all can see what happens when the scientifically illiterate try to understand an article on science.

the earth, or Gaia as the true believers like to call it, is close to a historical low point for the percentage of CO2 in the air.


So almost double what it was only 100 years ago is "a historical low point" is it? Wow, denialism is so much fun, just make stuff up and pretend like it's real!
Caliban
2.6 / 5 (10) Dec 17, 2013
Now I have heard it all, the rocks ate my CO2 and caused the earth to freeze.

I have some news for all of you AGW worshipers - the earth, or Gaia as the true believers like to call it, is close to a historical low point for the percentage of CO2 in the air.

There I have said it, The King Has No Clothes!

If you really want to save mankind perhaps you should go back to worshiping the sun for that is what controls the temperatures on earth.



The only thing which exceeds your stupidity is your total committment to denialscience un-truth.

Are you "M"entally "R"etarded(morally retarded goes without saying) --or merely a "M"o"R"on?

Oh, look --the King, unclothed!

MR166
2.3 / 5 (16) Dec 17, 2013
"So almost double what it was only 100 years ago is "a historical low point" is it? Wow, denialism is so much fun, just make stuff up and pretend like it's real!"

100 years in geological/climate time is a millisecond in human time. Admit it, the Chicken Little science of today is just a tool of crony capitalism and the politicians that they control.
MR166
2.3 / 5 (16) Dec 17, 2013
All you have to do is look at the day to day deltas of the CO2 ppm in the atmosphere to realize that the CO2 half time must be relatively short. The 3% that humans contribute are of no real significance.
obama_socks
1.6 / 5 (13) Dec 17, 2013
Now I have heard it all, the rocks ate my CO2 and caused the earth to freeze.
-Mr166

Yes...isn't that amazing? Who knew? LOL

Isn't Earth about due for another glaciation period. The rocks should all be checked for sequestering and absorption of CO2 and maybe other GHGs. The oceans are said to be somewhat full of CO2. The Sun's activity is at a low and the winter of 2013 - 2014 is gearing up to break all temps records for cold, ice and snow.
Even snow in summer in Australia...and snow in Cairo, Egypt.

But AGWites will say a pray to SaintAlGore to get rid of deniers of global warming.

As Indiana Jones says, "I have a bad feeling about this". Maybe a good amount of coal, oil and gas should be set aside for our use just in case Snowball Earth comes around again. You know how Mother Earth is capricious and is chock full of surprises. Never a dull moment anywhere in the world with the old gal.

I think I'll stock up on BBQ charcoal briquets.

m_(@L@)_m
obama_socks
1.7 / 5 (11) Dec 17, 2013
How strange that AGWites still haven't sent a delegation of their members to Communist China to inform the Chinese AGW deniers that the sky is falling and we're all going to die if China doesn't stop burning coal and other fossil fuels.

Somewhere under and around the Senkaku Islands in the East China Sea are huge oil and gas deposits, which is why the Commies will take control of those islands, by force if necessary.

China hungers for all that energy for its own use. Will AGWites tell the Commies to get lost?
As the story of China threatening Japan and the U.S. with war over the islands (oil and gas deposits) unfolds - we see the AlGore worshipping AGWites slinking off, tails between legs.
TheGhostofOtto1923
3.2 / 5 (9) Dec 17, 2013
The rocks should all be checked for sequestering and absorption of CO2 and maybe other GHGs
'THE rocks should ALL be checked'... what rocks are you referring to pussytard? Just curious.
The oceans are said to be somewhat full of CO2
THE oceans are SAID to be SOMEWHAT full...' Just what is it that you mean by 'somewhat' pussytard?
I think I'll stock up on BBQ charcoal briquets
-And dont forget BBQ sauce for all those mastodon ribs youll be a'cookin up during the ice age.
Yes...isn't that amazing? Who knew? LOL... How strange that AGWites... Commies will take control... AlGore worshipping AGWites...'


-Poor pussytard tries SOOO hard to fit in, to establish relationships, to beg for conversation... Perhaps if you didnt pretend to be a psychiatrist or a NASA engineer or a cal tech grad with many degrees or a nurse or a russian or a sweet sorghum farmer... or if you didnt immediately uprate your own comments... Maybe people would forget that you are a lying dimwit -?
obama_socks
1 / 5 (8) Dec 17, 2013
Poor insane Ghostofotto shows up to tell lies about me claiming that I ever said that I was a nasa engineer...OR a psychiatrist OR a nurse OR a russian OR a sorgum farmer...oh, and don't forget you calling me a ballet dancer (or was it belly dancer?).

Where are those links to what you claim I said, Otto? Where is your proof that Obama_socks pretends to be a psychiatrist or a nasa engineer or a nurse or a Russian or a farmer.

Give us your proof of these claims, and don't forget to provide proof of me ever saying anything about seeing your 900 foot glassy eyed Martians and your claim that I said anything about 40 pound lead boomerangs.

Your biggest problem besides extreme jealousy of others in this website, along with your mental disorders, is that you tell lies that require extraordinary proof...which you never provide.

I have asked you time and time again for the proof, and you never once have provided the proof with links.

All of Physorg is waiting for your proof, Otto.
Torbjorn_Larsson_OM
4.4 / 5 (7) Dec 17, 2013
The supercontinental cycle has long been implied as the quoted abstract notes, so it is nice to see tests of a predicted mechanism. (At formation, subduction under the supercontinental plates makes extensive volcanic chains.)

"after a billion years with no ice on the planet at all". This is arguable.

The same Global Circulation Models (GCM) of modern climate science that (finally!) predicts a late Archean climate that is consistent with geochemical constraints on greenhouse gases and temperatures also predicts the ushering in of global glaciations at the cyanobacteria oxygenation of the atmosphere. During the first 2 Ga of Earth history snow covered poles are present. There is no reason to think that changed much after the first glaciations.

Re the antiscience climate science trolling, it is humorous as always. But especially here since the eminent GCM models, that solves early Earth history, are a result of the strong AGW signal and how it has helped understand climate!
TheGhostofOtto1923
3.7 / 5 (6) Dec 17, 2013
Poor insane Ghostofotto shows up to tell lies about me claiming that I ever said that I was a nasa engineer...
NASA ENGR "a source of mirth and merriment for us all. Anyway, I took a few days off from NASA" '"they're calling me back to the station..." "sheer luck that the camera was pointed in the right direction...We did not anticipate it" "we were surprised to see what later turned out to be a cloud of dust from the impact. We had no way of telling immediately what it was, although some suggested that it might be the sky-crane..." [pussytard pretending to be a member of the Curiosity team]

-So you LIE knowing I have all your bullshit for reposting. Why IS that pussytard? Are you so hard up for attention that even insults feel good to you?
along with your mental disorders, is that you tell lies that require extraordinary proof
-Compulsive lying is a serious disorder. Yours is on par with Munchausen by Proxy. You lie even when the evidence is in your FACE.
Paulw789
1.8 / 5 (5) Dec 18, 2013
CO2 was 4,500 ppm at 750 Mya and 12,000 ppm at 635 Mya when the last two Snowball episodes were occurring.

http://www.snowba...ao08.pdf

The last Snowballs were caused by super-continents over the South Pole - think Antarctica times 20.

http://www.nature...aa.2.gif
Egleton
1 / 5 (3) Dec 18, 2013
The sun converts Hydrogen to Helium. Helium is a greenhouse gas for the sun. In 4.5 billion years the sun has increased its temperature 20%. Gaia has compensated by drawing down the CO2. We are now down to the last smidgon. That trick no longer works- and still the sun heats up.
So Gaia takes a huge gamble.
She breeds an ape/pig hybrid in the hopes that it can get her off this doomed rock, even if the Ape/pig releases the carbon that was sequestered to do it.
The ape/pig builds networks of thought and then begins the great pruning. Those who are not exercised in this endevour will experience apoptisis.
Prepare yourself.
Maggnus
3.7 / 5 (6) Dec 18, 2013
CO2 was 4,500 ppm at 750 Mya and 12,000 ppm at 635 Mya when the last two Snowball episodes were occurring.


How cow paul READ WHAT YOU CITE! In both cases, the CO2 level was the result of the snowball Earth, and the after effect of this extremely high CO2 level was a MASSIVE WARMING! It is this warming that reversed the glaciation., allowing the planet to emerge from the iceage it was gripped by.
kivahut
3 / 5 (2) Dec 22, 2013
I hate glaciers.