Hii! Can radiometric dating only be used on igneous rocks?
And can radiocarbon dating be used on sedimentary rock? Or all of them can't?
Thank you!
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Can radiometric dating be used on sedimentary rock?”From my understanding we do not date sedimentary rock but rather we date the fossils. The sedimentary layer is composed of sediments that came from areas like mountains, etc. So by dating the sedimentary layer, you are essentially estimating the age of the rocks in their initial placement, not the age of when the particular stratum was formed. So we can’t date the sedimentary rock layer to find the age of the fossil.
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Can radiometric dating only be used on igneous rocks? “No. Radiometric dating can involve many different types of radioisotopes. Depending on the radioisotope that we use, the substances we can date will vary. For instance, radiocarbon dating is used for dating fossils younger than 50,000 years or so, while potassium-argon dating is used to determine the age of igneous rock. We cannot use potassium-argon dating directly on fossils. (potassium 40 decays into argon which is a noble gas. Therefore, potassium - argon dating can only be done in substances that trap argon. This is generally, igneous rocks formed from volcanic eruptions.)
Although we can’t directly date a fossil using potassium-Argon dating, we can still use it to date fossils:
-> If the fossil is found in between two dateable igneous rock layers, we can obtain the date of formation of the igneous rocks. Then we can infer that the age of the fossil is between the ages of the two igneous rocks by using the law of superposition.
-> if the fossil is found in a dateable igneous rock, then we can date the igneous rock. The absolute age of the igneous rock would be around the same age as the fossil.
I hope that helps. This is my understanding. It could be wrong idk.