List the major radioactive isotopes, and their half lives, that are used for absolute dating of continental crust.List the major conditions that must be satisfied in order to use radioactivity to date igneous rocks.

Question

anonymous · Answer

Carbon dating can't be used on igneous rocks as it was never living

frostbite · Answer

Well the igneous rock just have to solidify, then it most contain some percentage of a radioactive isotope.
Hardly any of these however maybe potassium:

Uranium-238	4.5 billion years
Uranium-235	704 million years
Thorium-232	14.0 billion years
Rubidium-87	48.8 billion years
Potassium-40	1.25 billion years
Samarium-147	106 billion years

anonymous · Answer

thank you but i do not understand the  sentence "Hardly any of these however maybe potassium"

frostbite · Answer

I was thinking about what a igneous rock might contain... for example I don't think it contain Uranium 238 I only listed some of the few isotopes I can remember along with their half life. But it may contain Potassium-40

anonymous · Answer

oh okay. thanks for your help.

frostbite · Answer

No problem

aaronq · Answer

http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/mincomp.html#c3 potassium is the only element you listed that has a high enough part in the composition of igneous rocks.