Which radiometric dating method is commonly used to date volcanic rocks?

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Multiple Choice

Which radiometric dating method is commonly used to date volcanic rocks?

Explanation:
Potassium-Argon dating is used for volcanic rocks because these rocks are rich in potassium-bearing minerals and the dating relies on the decay of potassium-40 to argon-40. As magma erupts and the rock cools and solidifies, argon gas can escape from the melt. Once solid, the clock starts: potassium-40 continues to decay to argon-40, which becomes trapped in the crystal lattice. Measuring the ratio of potassium to argon gives the time elapsed since cooling, i.e., when the volcanic rock formed. This method works well over the long timescales typical of volcanic events and is more widely applicable to rocks than radiocarbon dating, which only works for organic material, or U-Pb dating in zircons, which depends on having zircons present.

Potassium-Argon dating is used for volcanic rocks because these rocks are rich in potassium-bearing minerals and the dating relies on the decay of potassium-40 to argon-40. As magma erupts and the rock cools and solidifies, argon gas can escape from the melt. Once solid, the clock starts: potassium-40 continues to decay to argon-40, which becomes trapped in the crystal lattice. Measuring the ratio of potassium to argon gives the time elapsed since cooling, i.e., when the volcanic rock formed. This method works well over the long timescales typical of volcanic events and is more widely applicable to rocks than radiocarbon dating, which only works for organic material, or U-Pb dating in zircons, which depends on having zircons present.

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