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potassium-argon dating |
Also found in: Dictionary/thesaurus, Wikipedia, Hutchinson | 0.03 sec. |
potassium-argon datingMethod 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. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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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. While the most frequently quoted age for the traps falls around 60 million to 65 million years old, he says, other estimates, determined primarily from potassium-argon dating, range from 80 million to 30 million years old. Potassium-argon dating of the volcanic rocks puts the islands' ages between about 1 million (western islands) and 4 million (eastern islands) years. |
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