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Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
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Author | Topic: Age Correlations and An Old Earth, Version 2 No 1 | |||||||||||||||||||||||||||||||||||||||||||
edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
However, I also understand that there is very little radiometric evidence on earth of a 4+ billion year formation.
I'm not sure of the amount of data, but certainly, it is hard to find the oldest pieces of the solar system.
It is also the case that material on earth arrived from outside of the solar system and thus at least conceivable might predate the formation of the earth by a large margin. No changes in decay rates would be required.
The clock starts when the uranium enters the rock as a mineral. Until that mineral forms, there is no clock. And you cannot start a U238 clock with daughter products. We don't date atoms. So, upon forming, a zircon crystal can only take in U238 that exists, not what has already gone down the decay chain.
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
Side issue: K40 dates don't really overlap with U238 dates do they? Do any radiometric dates overlap with U238 dates?
I'm not certain, but since the half life of K40 is 1/4th that of U238, I'd think there is some overlap. If it was less than a tenth, that might indicate otherwise. I'm certain that other methods do overlap. There are a plethora of them that have cropped up since I studied this subject.
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
But the argument we are discussing does not involve changes of decay rate. It is agreed that 4.5+ billion years passed since the formation of the materials in meteorites. The argument is that the material in the solar system is 4.55 billion years old, but that some fraction of that time is taken up between time the materials were created and the solar system was formed. So you are arguing for a "gap" old earth argument, which starts with the creation of "primordial" material and then jumps to modern creation of the earth and life?
As I understand your comment, my question takes what you say into account except I would have talked about U238 rather than your example of K40. If the answer is that U238 dates were reset during the formation of the solar system (or maybe even the universe), then the answer is also dependent on the process of formations. YECs would insist on hocus pocus that would not do resetting rather than some violent heat pressure intensive process that would reset. As I understand it there were several different radiometric methods used. U/Pb was one another was Pb/Pb, for example. These either need to "arrive" via decay over 4.55+ billion years OR the proportions of the isotopes need to be "jiggled" so that they appear to measure the same age. I found Snelling's paper to be more confusing than enlightening on how he thought it worked out, with a lot of extraneous information added that increased the obscuring of his results.
... If the answer is that U238 dates were reset during the formation of the solar system (or maybe even the universe), then the answer is also dependent on the process of formations. ... How do you think this would work? by our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
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JonF Member (Idle past 198 days) Posts: 6174 Joined: |
The clock starts when the uranium enters the rock as a mineral. Until that mineral forms, there is no clock. Perhaps too pedantic, but the clock can be re-set to zero by sufficient heating. One of the many nice things about zircons is that they have to be heated pretty seriously to do that, 900-1100 C based on a quick Google. Maybe there's a more widely agreed number but any way you slice it it's hot.
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
What consillience is violated? I am not aware of any radiometric dating in the vicinity of 4 billion years that couldn't be 'explained' as being primordial material. Dates of moon rocks? Dates of the occasional rare old dating earth rock? All possibly primordial material. So you are arguing for a "gap" old earth argument, which starts with the creation of "primordial" material and then jumps to modern creation of life? How far do you go back? Original hydrogen star formation that then made heavier elements in a universe some 12.7 (iirc) billion years old?
... Of the radiometric dates, C-14 dates are definitely of post creation origin and are already problematic for YECs, but of course they have separate issues and can be attacked without monkeying with decay rates. ... Which this thread addresses -- tree rings, lake varves, ice layers all show evidence for an earth older than YEC models and consilience with 14C (and other) radiometric systems.
... Also there are long aged radiometric dates that we know have been reset by the geology on earth. Those cannot be primordial. ... And these "reset" systems are used to date those (volcanic origin) rocks. Uranium decay inside zirconium crystals for instance.
... But does any of that get near 1 billion years old. I don't know, but my impression is that the primordial possibility is not so easily shaken. ... Well the age of first life has been set around 3.7 billion years ago by radiometric dating of objective evidence, so this evidence shows life on earth at that point in time, and the earth must have existed before then, and the existence of life would mean it is post primordial yes?
... At least I don't see such a counter argument spelled out in your post. Like I said, it allows for gap creationism. Edited by RAZD, : 7by our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
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NoNukes Inactive Member |
So you are arguing for a "gap" old earth argument, which starts with the creation of "primordial" material and then jumps to modern creation of the earth and life? Not exactly. I am asking why such a thing is inconsistent with radiometric dating at constant decay rates and nothing else. Obviously other dating methods pretty much rule out earth being only 10000 years old. But the material of our solar system, at least on an atomic level, was created some before the solar system was formed. I don't know exactly how long.
How do you think this would work? I think you are actually asking my question. If meteor rocks are the same age as the solar system that implies either a reset or a creation from a relatively nearby supernova. Matter and dust doesn't travel between stars at the speed of light does it?
As I understand it there were several different radiometric methods used. U/Pb was one another was Pb/Pb, for example. These either need to "arrive" via decay over 4.55+ billion years OR the proportions of the isotopes need to be "jiggled" so that they appear to measure the same age. That would not have any effect on the answer. We all agree that the meteor is 4.55 billion years old in at least some sense. Edited by NoNukes, : No reason given.Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) I have never met a man so ignorant that I couldn't learn something from him. Galileo Galilei If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined:
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Perhaps too pedantic, but the clock can be re-set to zero by sufficient heating. One of the many nice things about zircons is that they have to be heated pretty seriously to do that, 900-1100 C based on a quick Google. Maybe there's a more widely agreed number but any way you slice it it's hot.
It should always be remembered that, one way or another, what we see are cooling dates when working with magmatic rocks. However, since Pb is relatively immobile, these dates are not as susceptible to resetting as would Ar. Partial melting would be a disaster in some cases.
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NoNukes Inactive Member |
Yes, K40 dates do overlap with U238. I had not considered them. But do they address the problem? Do we have any 4 billion year old K40 dates that we know were set to zero on earth?
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) I have never met a man so ignorant that I couldn't learn something from him. Galileo Galilei If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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JonF Member (Idle past 198 days) Posts: 6174 Joined: |
From Geological Time I see:
(actually K40 in the Ar-Ar method has been used to date the eruption of Vesuvius 76 AD, or about 0.002 mya, somewhat of a tour de force). And I'm pretty sure that other isotopes such as Samarium are also comparable. One could also dive into Dalrymple and look at TABLE 4.1 Radiometric Ages of Some Early Archean and Related Rocks of the North Atlantic Craton to see how they do overlap and agree. (Note that in each of the two parts of the table the units are listed in stratigraphic order so you can see the close correlation to that). Side note: Wherever you have some U238 you also have some U237 and you measure the Pb206 and Pb208 and get two largely independent dates. If they agree they are "concordant" and pretty solidly established. If they disagree they are "discordant" and a pretty solid age may be establishable. Nobody call this "U238 dating".
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
How do you think this would work? I think you are actually asking my question. If meteor rocks are the same age as the solar system that implies either a reset or a creation from a relatively nearby supernova. Matter and dust doesn't travel between stars at the speed of light does it? My understanding is that the clock is "set" when the small particles of matter from older novae accumulates into larger balls of matter so that the parent\daughter material share the same location. One of the problems with the lead dating (see cosmos ?) was contamination by lead from other sources (which would include "primordial" lead from older decay not associated by location with the parent). Edited by RAZD, : ..qsby our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
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JonF Member (Idle past 198 days) Posts: 6174 Joined:
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Yes, K40 dates do overlap with U238. As do many others.
Do we have any 4 billion year old K40 dates that we know were set to zero on earth? Ther are lots of dating methods. The oldest claimed date I know of for such is 4.28bya, Neodymium-142 Evidence for Hadean Mafic Crust (free registration required). The abstract:
quote: The Acasta gneiss near Great Slave Lake in north central Canada is purty darn well established at 4.03 bya, e.g. Age of the world's oldest rocks refined using Canada's SHRIMP: the Acasta gneiss complex, Northwest Territories, Canada.
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Ther are lots of dating methods. There were 10 different methods listed on the graph, and presumably these would work equally well on earth rocks.
The oldest claimed date I know of for such is 4.28bya,... The Acasta gneiss near Great Slave Lake in north central Canada is purty darn well established at 4.03 bya, ... Yes the major problem with dating the earth directly is finding an outcropping of old rock. by our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
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NoNukes Inactive Member
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The oldest claimed date I know of for such is 4.28bya, Neodymium-142 Evidence for Hadean Mafic Crust (free registration required). The abstract: Thanks JonF. I think you, NosyNed, edge, and RAZD guys have addressed my question quite completely. Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) I have never met a man so ignorant that I couldn't learn something from him. Galileo Galilei If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined:
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quote:Correct. That is why I referred to it as a U238 'clock'. I figure that gives me more poetic license.
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NoNukes Inactive Member |
ide note: Wherever you have some U238 you also have some U237 and you measure the Pb206 and Pb208 and get two largely independent dates. I don't understand this particular point. Did you mean U235 rather than U237? At a time when U238 is getting incorporated into a mineral there should not be any amount of U237 around, should there? Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) I have never met a man so ignorant that I couldn't learn something from him. Galileo Galilei If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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