Why new rocks mean they just cooled?

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Offline greeniemax

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Why new rocks mean they just cooled?
« on: 30/04/2012 12:17:37 »

To judge the age of a rock radio decay method is used, look at how much of uranium for instance has decayed, getting the half life of these minerals age of a rock or body of rocks could be guessed.

So it is assumed that when rock formed from liquid magma state to solid rock state, it started decaying.

Problem is heat does not slow down the decay process, thus either the results are all wrong, there is another reason or decay does slow down when temperature is increased.

Any suggestions?
Greenie Max


Offline CliffordK

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Re: Why new rocks mean they just cooled?
« Reply #1 on: 30/04/2012 14:55:55 »
If liquid and solid rock is made up of the same isotopes, then they should be indistinguishable.

What about looking at the radon content?

Your liquid rock might tend to exclude more radon, but it might be trapped in solid rock.  However, that might be dependent on the environment that the rock was formed.


Offline Phractality

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Re: Why new rocks mean they just cooled?
« Reply #2 on: 01/05/2012 02:29:18 »
When magma solidifies, some of the minerals crystalize. Newly formed crystals of a uranium compound do not contain the elements into which uranium decays. By measuring the ratio of uranium to its decay products within the crystal, you can determine how long ago the crystal formed.

Imagination is more important than knowledge. Einstein