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potassium-argon dating

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potassium-argon dating

Method for determining the age of igneous rocks based on the amount of argon-40 in the rock. Radioactive potassium-40 decays to argon-40 with a half-life of about 1.3 billion years, making this method useful for dating rocks that are billions of years old. A more sophisticated method, called argon-argon dating, provides a more accurate estimate of the original potassium-40 content by means of the ratio of argon-40 to argon-39 in the rock, thus yielding a more accurate age determination. See also dating.

potassium-argon dating [pə′tas·ē·əm ′är‚gän ′dād·iŋ]
(geology)
Dating of archeological, geological, or organic specimens by measuring the amount of argon accumulated in the matrix rock through decay of radioactive potassium.
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Geophysicist Michael McWilliams of Stanford University dated the Brunhes-Matuyama transition at 780,000 years ago using the argon-argon technique, a variation of the standard potassium-argon dating method.
New date resets geologic clocks by Monastersky, Richard / Science News
Potassium-argon dating of the volcanic rocks puts the islands' ages between about 1 million (western islands) and 4 million (eastern islands) years.
Gauge the Galapagos with a younger age by Science News
 
 
 
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