potassium—argon dating

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potassium—argon dating (K—Ar method) Geologic dating technique based on the radioactive decay of potassium (40K) to argon (40Ar). This potassium isotope has a half-life (see DECAY CONSTANT) of 1.3 billion (109) years, making this a valuable dating method. The minimum age limit for this dating method is about 250 000 years.

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