Science! help Please!?

Question

What rocks can be dated radiometrically and which ones can't?

Why can't sedimentary rock be radiometrically dated?

Answer 1

i think igneous and metamorphic rock can be dated

sedi. cant

Answer 2

Sedimentary can't be dated because they are a conglomeration of different rock particles.

Answer 3

Well first off, in order for rocks to be dated radiometrically, they must have at least one radioactive element in their chemical composition (like Carbon-14). In general, igneous rocks are the easiest ones to date with this method.

Although metamorphic rocks are also commonly dated this way, they may suffer alterations in their crystalline form, which could disturb the relation between the radioactive nuclide and the daughter nuclide.

Sedimentary rocks are even harder to date through radiometry because sedimentary rocks are precisely that - a rock formed by various sediments, therefore the amounts of different material its made up of complicate the chances of getting an accurate date.