Isochron Plot

[grace24]

How does one distinguish Isochron plot to help determine the presence of daughter isotopes in a rock when it first formed, before the parent atoms had yet to decayed? From what i understand, if daughter atoms were present and are not accounted for, thus the rock will be mislead to appearance of age if the sample is not a closed system.

Rocks have minerals inside them. How do i plot them? How do i measure them? There is a difference between a mineral age plot, and the whole rock age plot. Can someone tell me the difference and what they are?

 

[Agonaces of Susa]

First you look at the geological strata where the rock is and that will give you a basic idea of it's age (Archaean, Holocene, etc).

If it's an ocean rock then you know it's age is Jurassic or younger.

After that, I believe the methodology is called inductively coupled plasma mass spectrometry (ICP-MS).

http://en.wikipedia.org/wiki/Inductively_coupled_plasma_mass_spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) is a type of mass spectrometry that is highly sensitive and capable of the determination of a range of metals and several non-metals at concentrations below one part in 10^12 (part per trillion).

 

[Split Rock]

How does one distinguish Isochron plot to help determine the presence of daughter isotopes in a rock when it first formed, before the parent atoms had yet to decayed? From what i understand, if daughter atoms were present and are not accounted for, thus the rock will be mislead to appearance of age if the sample is not a closed system.

Rocks have minerals inside them. How do i plot them? How do i measure them? There is a difference between a mineral age plot, and the whole rock age plot. Can someone tell me the difference and what they are?

Isochron dating makes no assumptions about daughter isotopes, and will tell you if you have lost or gained such material (ie if the system was ever open). Basically, you make additional measurements of a different isotope of the daughter element in question. The resulting plot will tell you if you have lost or gained daughter isotope via a loss of colinearity of the plot.
Isochron Dating

 

[grace24]

First you look at the geological strata where the rock is and that will give you a basic idea of it's age (Archaean, Holocene, etc).

If it's an ocean rock then you know it's age is Jurassic or younger.

I meant like, say, a rock for example. It has 4 minerals inside them (some rocks are made of one or more minerals by the way). These minerals includes biotite, feldspar, olivine, and quartz. You have Rb-87 which is the parent isotopes in all 4 separate minerals, and also the daugther element Sr-87 in the same sample. Suppose that these 4 minerals came from the same rock. Now how do i plot them? The graph look something like this.

 

[Agonaces of Susa]

That is way beyond my circle of competence. Sorry...

Let us know if you find out the answer...

 

[grace24]

Isochron dating makes no assumptions about daughter isotopes, and will tell you if you have lost or gained such material (ie if the system was ever open). Basically, you make additional measurements of a different isotope of the daughter element in question. The resulting plot will tell you if you have lost or gained daughter isotope via a loss of colinearity of the plot.
Isochron Dating

If the data point is not a straight line it would suspect to be open system where either the parent or daughter have left the same during its history.

 

[grace24]

That is way beyond my circle of competence. Sorry...

Let us know if you find out the answer...

It's ok chief. I am new to this. My first day reading on it.

 

[Naraoia]

If the data point is not a straight line it would suspect to be open system where either the parent or daughter have left the same during its history.

Yes, and that's exactly the point, as far as I understand. If the points are off the line, it warns that you cannot use the sample in question for accurate dating.

 

[Naraoia]

Never mind, I think I was talking bullcrap...

 

[juvenissun]

I meant like, say, a rock for example. It has 4 minerals inside them (some rocks are made of one or more minerals by the way). These minerals includes biotite, feldspar, olivine, and quartz. You have Rb-87 which is the parent isotopes in all 4 separate minerals, and also the daugther element Sr-87 in the same sample. Suppose that these 4 minerals came from the same rock. Now how do i plot them? The graph look something like this.

You are asking multiple questions in one sentence. You should consider them one at a time so the answers won't confuse you.

How to plot involves questions like what to plot or how to get data.

The minerals in rock question involves how do you sample and what kind of information are you looking for. For example, what kind of rock to date and how many rocks to date.

In short, you are asking too many questions and it would be difficult to give a simple and helpful answer. [that means, the best answer would be: go back to read a few chapters in the textbook]

 

[Ar Cosc]

AFAIK, for Uranium-Lead dating, zircon crystals are used, which strongly reject lead when they are being formed, but don't mind uranium, so it is a fairly safe assumption that any lead in the crystals has come from uranium decay. It's presumably similar for other radiometric dating methods

 

[Naraoia]

You are asking multiple questions in one sentence. You should consider them one at a time so the answers won't confuse you.

How to plot involves questions like what to plot or how to get data.

My problem with that post isn't so much the number of questions, but the lack of them. I mean, he asks, "how do I plot them", and then shows what the plot will look like. Then what was the question again??? Does he want us to explain the plot? TalkOrigins does that quite well, so he doesn't even need a textbook.

 

[juvenissun]

My problem with that post isn't so much the number of questions, but the lack of them. I mean, he asks, "how do I plot them", and then shows what the plot will look like. Then what was the question again??? Does he want us to explain the plot? TalkOrigins does that quite well, so he doesn't even need a textbook.

You see no question and I see too many questions. It is the same thing. (lost you again? )

 

[Naraoia]

You see no question and I see too many questions. It is the same thing. (lost you again? )

Ah, language!

Anyway, I think we can agree: grace24 needs to clarify what he's asking.

 

[juvenissun]

Ah, language!

Anyway, I think we can agree: grace24 needs to clarify what he's asking.

An usual fact is: when the question is clarified, then it is likely to be answered too.