This may sound like a stupid question but ,, I,m board and this came to mind. now after more than a week I can't seem to shake the question. so I thought I'd toss it out to you guys.
I have been wondering what age a carbon date test would give for a newly formed rock from a volcano?
This may sound like a stupid question but ,, I,m board and this came to mind. now after more than a week I can't seem to shake the question. so I thought I'd toss it out to you guys.
This may sound like a stupid question but ,, I,m board and this came to mind. now after more than a week I can't seem to shake the question. so I thought I'd toss it out to you guys.
Carbon 14 dating isn't used on rocks.
Carbon 14 occurs in nature from Cosmic rays hitting Nitrogen 14 and turning it into C14. The C14 is oxidized to become CO2 and in this form it enters the biosphere.
Because of the VERY small percent of Carbon that is C14 (C14 = 0.0000000001% of the Carbon in an organism) and because of its almost exclusive pathway for formation and because its only incorporated into an organism when it is living, one can use the relatively rapid decay rate of C14 (5,568 year half life) as a guide to how long ago the organism died.
i.e. if it has 1/2 as much C14 as a living organism than its 5,568 years since it died, if it has 1/4 as much C14 than its 11,136 years old, etc etc.
Its limit of its useful ability is related to the short half life of C14 and thus it is not useful for more than ~ 10 half lives or ~ 60,000 years (better analytics might get this back a bit further).
For dating of rocks one uses OTHER radioactive isotopes besides Carbon such as Uranium 235 and 238. Rubidium 87, Potassium 40 etc. that produce predictable decay patterns typically stopping at a relatively unique and non-radioactive daughter element thus allowing one to use reatios of these elements to determine the age the ORIGINAL material was formed.
Arthur
Carbon 14 occurs in nature from Cosmic rays hitting Nitrogen 14 and turning it into C14. The C14 is oxidized to become CO2 and in this form it enters the biosphere.
Because of the VERY small percent of Carbon that is C14 (C14 = 0.0000000001% of the Carbon in an organism) and because of its almost exclusive pathway for formation and because its only incorporated into an organism when it is living, one can use the relatively rapid decay rate of C14 (5,568 year half life) as a guide to how long ago the organism died.
i.e. if it has 1/2 as much C14 as a living organism than its 5,568 years since it died, if it has 1/4 as much C14 than its 11,136 years old, etc etc.
Its limit of its useful ability is related to the short half life of C14 and thus it is not useful for more than ~ 10 half lives or ~ 60,000 years (better analytics might get this back a bit further).
For dating of rocks one uses OTHER radioactive isotopes besides Carbon such as Uranium 235 and 238. Rubidium 87, Potassium 40 etc. that produce predictable decay patterns typically stopping at a relatively unique and non-radioactive daughter element thus allowing one to use reatios of these elements to determine the age the ORIGINAL material was formed.
Arthur
I want to understand this also... (thanks Paul, its bugging me too)
Sooooooo, I know in Idaho there is a big valley that is nothing but ancient lava, dated to a million or so years. Don't quote me on that, I am sure I am wrong! Then when I visited Hawaii, they are able to tell the age of all the flows from current to old.
How does lava formed last week look on the spectrum of what ever radioactive isotope that is most commonly used, vs. lava that is 1 meeeeleeon
years old?
Sooooooo, I know in Idaho there is a big valley that is nothing but ancient lava, dated to a million or so years. Don't quote me on that, I am sure I am wrong! Then when I visited Hawaii, they are able to tell the age of all the flows from current to old.
How does lava formed last week look on the spectrum of what ever radioactive isotope that is most commonly used, vs. lava that is 1 meeeeleeon
years old?
Its based on the same idea as the C14 example, just using different (and much longer lasting) isotopes.
Here's a source for some decent info:
http://hyperphysics.phy-astr.gsu.edu/hbase.../clkroc.html#c1
Arthur
Here's a source for some decent info:
http://hyperphysics.phy-astr.gsu.edu/hbase.../clkroc.html#c1
Arthur
adoucette,
Thanks, I think that "They" ask the question better than I did.
>How does lava formed last week look on the spectrum of what ever radioactive isotope that is most commonly used, vs. lava that is 1 meeeeleeon years old?
The link was good but didn't answer the question.
(Well the link did say that with lava, the date would fix at the last time it was molten).
My thoughts were,,, Given subduction zones in the mantel, that may recycle the rocks. I could see rock dating being allot higher (older) than the age of the formation (or re-formation) of a "new" rock.
Thanks, I think that "They" ask the question better than I did.
>How does lava formed last week look on the spectrum of what ever radioactive isotope that is most commonly used, vs. lava that is 1 meeeeleeon years old?
The link was good but didn't answer the question.
(Well the link did say that with lava, the date would fix at the last time it was molten).
My thoughts were,,, Given subduction zones in the mantel, that may recycle the rocks. I could see rock dating being allot higher (older) than the age of the formation (or re-formation) of a "new" rock.
Rocks that melt have their "clock" reset.
The traditional method for dealing with most igneous rocks is using the ratio of radioactive Potassium 40 to its stable daughter Argon 40. P40 has a half life of 1.2 billion years so it works pretty well for any rocks that contain it when they are formed.
Upon re-melting any existing Ar40 escapes so when magma solidifies THEN the "clock" starts as X amount of natural occuring P40 atoms start decaying at a set rate down into Y amount of Ar40.
Because Ar 40 doesn't form any other way, one can count the number of atoms of each in a sample and from that determine the amount of time since the sample solidified.
For other rocks other Parent /Daughter relationships can be exploited:
The traditional method for dealing with most igneous rocks is using the ratio of radioactive Potassium 40 to its stable daughter Argon 40. P40 has a half life of 1.2 billion years so it works pretty well for any rocks that contain it when they are formed.
Upon re-melting any existing Ar40 escapes so when magma solidifies THEN the "clock" starts as X amount of natural occuring P40 atoms start decaying at a set rate down into Y amount of Ar40.
Because Ar 40 doesn't form any other way, one can count the number of atoms of each in a sample and from that determine the amount of time since the sample solidified.
For other rocks other Parent /Daughter relationships can be exploited:
CODE
Parent Daughter Half-life
Uranium-235 Lead-207 0.7 billion years
Uranium-238 Lead-206 4.47
Rubidium-87 Strontium-87 48.8
Thorium-232 Lead-208 14.0
Rhenium-187 Osmium-187 43.0
Uranium-235 Lead-207 0.7 billion years
Uranium-238 Lead-206 4.47
Rubidium-87 Strontium-87 48.8
Thorium-232 Lead-208 14.0
Rhenium-187 Osmium-187 43.0
Arthur
K40, not P40.
P40 would be phosphorus 40 which is well above the neutron drip line, and would decay instantly, emitting a torrent of neutrons.
Aside from that, everythign that Arthur has said is correct, for what it's worth.
In fact, reheating is one of the problems that they've been having with using Zircons to date early rocks from Australia and Greenland. Sometimes Metamorphic processes can reheat the the zircons to the point where the clocks are reset without actually melting the crystals, giving a (potentially) false reading.
In fact, I believe that recent research has used this idea to determine the thermal history of ancient rocks, by determening which clocks have been reset, and which ones haven't, and how long ago various clocks have been reset, we can determine, to some degree, what has happened to some rocks in the time since they have formed.
Also, any false readings tend to be younger, rather then older, for example, if you were to take a piece of coal to a lab, from a seam dated to say, the cretacous period, the date reading you got back would be typically 50-60 thousand years, purely and simply because of experimental error. Any C-14 that would have been present when the plant material died should long since have decayed, so we're putting something in that has a level below the level of errors in the machine, so you get a very low, but erroneous result, which gives you, by Carbon-14 standards, a very old, but erroneous result, but we know that the Coal is 65 million years old, and hence the result is erring on the young side, by a significant amount.
As an aside, the temperature at which the clocks are reset is the blocking temperature.
argon-argon (Ar-Ar)
fission track dating
helium (He-He)
iodine-xenon (I-Xe)
lanthanum-barium (La-Ba)
lead-lead (Pb-Pb)
lutetium-hafnium (Lu-Hf)
neon-neon (Ne-Ne)
optically stimulated luminescence dating
potassium-argon (K-Ar)
radiocarbon dating
rhenium-osmium (Re-Os)
rubidium-strontium (Rb-Sr)
samarium-neodymium (Sm-Nd)
uranium-lead (U-Pb)
uranium-lead-helium (U-Pb-He)
uranium-thorium (U-Th)
uranium-uranium (U-U)
P40 would be phosphorus 40 which is well above the neutron drip line, and would decay instantly, emitting a torrent of neutrons.
Aside from that, everythign that Arthur has said is correct, for what it's worth.
In fact, reheating is one of the problems that they've been having with using Zircons to date early rocks from Australia and Greenland. Sometimes Metamorphic processes can reheat the the zircons to the point where the clocks are reset without actually melting the crystals, giving a (potentially) false reading.
In fact, I believe that recent research has used this idea to determine the thermal history of ancient rocks, by determening which clocks have been reset, and which ones haven't, and how long ago various clocks have been reset, we can determine, to some degree, what has happened to some rocks in the time since they have formed.
Also, any false readings tend to be younger, rather then older, for example, if you were to take a piece of coal to a lab, from a seam dated to say, the cretacous period, the date reading you got back would be typically 50-60 thousand years, purely and simply because of experimental error. Any C-14 that would have been present when the plant material died should long since have decayed, so we're putting something in that has a level below the level of errors in the machine, so you get a very low, but erroneous result, which gives you, by Carbon-14 standards, a very old, but erroneous result, but we know that the Coal is 65 million years old, and hence the result is erring on the young side, by a significant amount.
As an aside, the temperature at which the clocks are reset is the blocking temperature.
argon-argon (Ar-Ar)
fission track dating
helium (He-He)
iodine-xenon (I-Xe)
lanthanum-barium (La-Ba)
lead-lead (Pb-Pb)
lutetium-hafnium (Lu-Hf)
neon-neon (Ne-Ne)
optically stimulated luminescence dating
potassium-argon (K-Ar)
radiocarbon dating
rhenium-osmium (Re-Os)
rubidium-strontium (Rb-Sr)
samarium-neodymium (Sm-Nd)
uranium-lead (U-Pb)
uranium-lead-helium (U-Pb-He)
uranium-thorium (U-Th)
uranium-uranium (U-U)
QUOTE (Trippy+Dec 9 2007, 04:28 AM)
K40, not P40.
P40 would be phosphorus 40 which is well above the neutron drip line, and would decay instantly, emitting a torrent of neutrons.
Ooops.
I can't believe I did that.
I believe KNO3 was the first chemical compound I ever worked with.
Making you know what.
Arthur
P40 would be phosphorus 40 which is well above the neutron drip line, and would decay instantly, emitting a torrent of neutrons.
Ooops.
I can't believe I did that.
I believe KNO3 was the first chemical compound I ever worked with.
Making you know what.
Arthur
QUOTE (adoucette+Dec 10 2007, 02:09 AM)
Ooops.
I can't believe I did that.
I believe KNO3 was the first chemical compound I ever worked with.
Making you know what.
Arthur
Probably the same thing I put too much sulfur in the first time I tried >_>
I can't believe I did that.
I believe KNO3 was the first chemical compound I ever worked with.
Making you know what.
Arthur
Probably the same thing I put too much sulfur in the first time I tried >_>
Uranium-235 Lead-207 0.7 billion years
OK, I understand this and that of course just raised another question.
Just as an example I took the Uranium-235 but I'm sure it's (other than time) the same for all matter. In 0.7 billion years Uranium-235 will decay into Lead-207.
Where did the parts that decayed go?
OK, I understand this and that of course just raised another question.
Just as an example I took the Uranium-235 but I'm sure it's (other than time) the same for all matter. In 0.7 billion years Uranium-235 will decay into Lead-207.
Where did the parts that decayed go?
QUOTE (Trippy+Dec 9 2007, 03:03 PM)
Probably the same thing I put too much sulfur in the first time I tried >_>
Potassium perchlorate and sugar is fun, too...
Potassium perchlorate and sugar is fun, too...
QUOTE (Sapo+Dec 24 2007, 05:31 PM)
Potassium perchlorate and sugar is fun, too...
I much prefer super-heated francium and fluorine.
I much prefer super-heated francium and fluorine.
QUOTE (paul h+Dec 25 2007, 05:58 AM)
Uranium-235 Lead-207 0.7 billion years
OK, I understand this and that of course just raised another question.
Just as an example I took the Uranium-235 but I'm sure it's (other than time) the same for all matter. In 0.7 billion years Uranium-235 will decay into Lead-207.
Where did the parts that decayed go?
They hang around in the Zircon crystal.
U-235 decays into Pb-207 through the Actinium Series and U-238 decays into Pb-206 through the Radium Series
For the most part, the Zircon can be considered a closed system. The decay products careen away from the site of the parent nucleus, leaving fission tracks, and creating micro fissures in the crystal.
Sometimes, if there is sufficient damage to the crystal, and the crystal is open, and looses lead to the environment, there's a process by which that can be corrected for.
Given the different decay rates of U-235 and U-238, the lead is produced at different rates, and will therefore be lost at different rates, resulting in different ages. But, if you sample many crystals,, you generally find that you have a range of ages, and two ages can be determined, the first is the age of the sample, and the second is the age at which the system started behaving in an open manner, instead of a closed one (although some people dispute that).
But, essentially, the decay products hang around in the crystal causing (further) damage to the cyrstal structure as they decay further.
OK, I understand this and that of course just raised another question.
Just as an example I took the Uranium-235 but I'm sure it's (other than time) the same for all matter. In 0.7 billion years Uranium-235 will decay into Lead-207.
Where did the parts that decayed go?
They hang around in the Zircon crystal.
U-235 decays into Pb-207 through the Actinium Series and U-238 decays into Pb-206 through the Radium Series
For the most part, the Zircon can be considered a closed system. The decay products careen away from the site of the parent nucleus, leaving fission tracks, and creating micro fissures in the crystal.
Sometimes, if there is sufficient damage to the crystal, and the crystal is open, and looses lead to the environment, there's a process by which that can be corrected for.
Given the different decay rates of U-235 and U-238, the lead is produced at different rates, and will therefore be lost at different rates, resulting in different ages. But, if you sample many crystals,, you generally find that you have a range of ages, and two ages can be determined, the first is the age of the sample, and the second is the age at which the system started behaving in an open manner, instead of a closed one (although some people dispute that).
But, essentially, the decay products hang around in the crystal causing (further) damage to the cyrstal structure as they decay further.
QUOTE (Princess Bluebell+Dec 24 2007, 12:58 PM)
I much prefer super-heated francium and fluorine.
oh. BS? I thought you knew better.
oh. BS? I thought you knew better.
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