How do we date sedimentary rocks?

[juvenissun]

Please expand on that response. The way we radiometrically date other materials cannot be applied to sedimentary rocks becuase the constituent grains will have different ages. So if there is no cement to radiometrically date, how do you propose it is done?

Date the whole rock. You WILL get an "age".

You need to ask yourself: why do you want to have that age?

(you certainly can use it to support YEC)

 

[juvenissun]

Does U/Pb age of the zircons in a granite kitchen countertop tell you how old the house is?

Sorry, pal. You are now sitting at the bottom of my list with people like that Strawberry guy.

 

[PsychoSarah]

Date the whole rock. You WILL get an "age".

You need to ask yourself: why do you want to have that age?

(you certainly can use it to support YEC)

1 no, you can't use it for that reason, and 2, attempting to date a whole mass of rock would be folly in the case of sedimentary rock.

 

[juvenissun]

1 no, you can't use it for that reason, and 2, attempting to date a whole mass of rock would be folly in the case of sedimentary rock.

Whole-rock dating of sedimentary rocks is a very common practice.

 

[PsychoSarah]

Whole-rock dating of sedimentary rocks is a very common practice.

Ok, then describe how the process works for everyone.

 

[Atheos canadensis]

Date the whole rock. You WILL get an "age".

You need to ask yourself: why do you want to have that age?

(you certainly can use it to support YEC)

Please elaborate more. You can't "date the whole rock" because every sample of the rock you test will contain grains with different ages. How does this furnish the investigator with an age? If you have some examples of whole sedimentary rocks being dated, please post them for our edification.

 

[Loudmouth]

Sorry, pal. You are now sitting at the bottom of my list with people like that Strawberry guy.

Then please tell us how dating a zircon in a sandstone tells us the time of deposition.

 

[juvenissun]

Then please tell us how dating a zircon in a sandstone tells us the time of deposition.

I don't know. It depends on several conditions.

 

[juvenissun]

Please elaborate more. You can't "date the whole rock" because every sample of the rock you test will contain grains with different ages. How does this furnish the investigator with an age? If you have some examples of whole sedimentary rocks being dated, please post them for our edification.

I don't like to throw article to lay people. But if this is what you asked for:

http://www-odp.tamu.edu/publications/126_SR/VOLUME/CHAPTERS/sr126_44.pdf

A simple one minute search on google.

 

[juvenissun]

Ok, then describe how the process works for everyone.

You don't do that until you have a reason to use the age.
Or, you have a lot of resources in excess.

 

[Mr Strawberry]

Sorry, pal. You are now sitting at the bottom of my list with people like that Strawberry guy.

Lol, had your pride hurt have you?

 

[Mr Strawberry]

I don't like to throw article to lay people. But if this is what you asked for:

http://www-odp.tamu.edu/publications/126_SR/VOLUME/CHAPTERS/sr126_44.pdf

A simple one minute search on google.

Always a good idea to read the article before you post a link to it.

Of course, you not being a geologist, it wouldn't make much difference really.

 

[PsychoSarah]

You don't do that until you have a reason to use the age.
Or, you have a lot of resources in excess.

All I asked was for you to explain how it works.

 

[Atheos canadensis]

I don't like to throw article to lay people. But if this is what you asked for:

http://www-odp.tamu.edu/publications/126_SR/VOLUME/CHAPTERS/sr126_44.pdf

A simple one minute search on google.

Don't worry about me; I know my way around a geology paper. And this paper is discussing K-Ar dating of igneous rocks, not sedimentary rocks. This doesn't therefore answer the question of how geologists can radiometrically date an entire sedimentary rock. Perhaps you could quote the part you think discusses the dating of a sedimentary rock. I'm still waiting for you to explain how one can date a sedimentary rock, particularly an un-cemented one, given that the various constituent grains will return different ages

 

[Mr Strawberry]

Don't worry about me; I know my way around a geology paper. And this paper is discussing K-Ar dating of igneous rocks, not sedimentary rocks. This doesn't therefore answer the question of how geologists can radiometrically date an entire sedimentary rock. Perhaps you could quote the part you think discusses the dating of a sedimentary rock. I'm still waiting for you to explain how one can date a sedimentary rock, particularly an un-cemented one, given that the various constituent grains will return different ages

Yes, even I noticed the word 'biostratigraphy' when the paper talked about sedimentary rocks.

As juve said, he spent one minute googling it. He almost certainly did no more than look at the title of the paper. He hasn't read it, and I personally don't think it would mean much to him if he did try and read it. (Just my opinion.)

 

[juvenissun]

Don't worry about me; I know my way around a geology paper. And this paper is discussing K-Ar dating of igneous rocks, not sedimentary rocks. This doesn't therefore answer the question of how geologists can radiometrically date an entire sedimentary rock. Perhaps you could quote the part you think discusses the dating of a sedimentary rock. I'm still waiting for you to explain how one can date a sedimentary rock, particularly an un-cemented one, given that the various constituent grains will return different ages

But it also dated the "whole-rock" oceanic sediments.

 

[juvenissun]

All I asked was for you to explain how it works.

It gives an "average age". It is meaningful only if one knows how to use that age.

 

[PsychoSarah]

It gives an "average age". It is meaningful only if one knows how to use that age.

Average age of sedimentary rock wouldn't be useful. Show me an instance in which it has been used within the past decade.

 

[Atheos canadensis]

But it also dated the "whole-rock" oceanic sediments.

Please quote the part where they discuss dating sedimentary rock. I know they talk about drilling through oceanic sedimentary rock, but they didn't date it as far as I can tell. You should quote the relevant sentence.

It gives an "average age". It isms meaningful only if one knows how to use that age.

Such an average age would not really be useful. If you're looking at a rock that was deposited 75Ma but contains grains that are from the Precambrian (say 1Ga) and others that are from 250Ma, your average would be 625Ma. That average is not a useful number.
Please explain in detail how such an average is useful.

 

[juvenissun]

Please quote the part where they discuss dating sedimentary rock. I know they talk about drilling through oceanic sedimentary rock, but they didn't date it as far as I can tell. You should quote the relevant sentence.

Such an average age would not really be useful. If you're looking at a rock that was deposited 75Ma but contains grains that are from the Precambrian (say 1Ga) and others that are from 250Ma, your average would be 625Ma. That average is not a useful number.
Please explain in detail how such an average is useful.

All right. That article did not say it. My mistake.

This one surely does.