Potassium argon dating advantages

Ar–Ar dating is a similar technique which compares isotopic ratios from the same portion of the sample to avoid this problem.

Due to the long half-life, the technique is most applicable for dating minerals and rocks more than 100,000 years old.

is known to cause grave problems in regional geochronology studies.If so, then the K-Ar and Ar-Ar "dating" of crustal rocks would be similarly questionable.When muscovite (a common mineral in crustal rocks) is heated to 740°-860°C under high Ar pressures for periods of 3 to 10.5 hours it absorbs significant quantities of Ar, producing K-Ar "ages" of up to 5 billion years, and the absorbed Ar is indistinguishable from radiogenic argon ( In other experiments muscovite was synthesized from a colloidal gel under similar temperatures and Ar pressures, the resultant muscovite retaining up to 0.5 wt% Ar at 640°C and a vapor pressure of 4,000 atmospheres.Thus all K-Ar and Ar-Ar "dates" of crustal rocks are questionable, as well as fossil "dates" calibrated by them.Potassium–argon dating, abbreviated K–Ar dating, is a radiometric dating method used in geochronology and archaeology.

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