40Ar/39Ar technique of KAr dating: A comparison with the conventional technique

Earth and Planetary Science Letters
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Abstract

K-Ar ages have been determined by the40Ar/39Ar total fusion technique on 19 terrestrial samples whose conventional K-Ar ages range from 3.4 my to nearly 1700 my. Sample materials included biotite, muscovite, sanidine, adularia, plagioclase, hornblende, actinolite, alunite, dacite, and basalt. For 18 samples there are no significant differences at the 95% confidence level between the Ksingle bondAr ages obtained by these two techniques; for one sample the difference is 4.3% and is statistically significant. For the neutron doses used in these experiments (≈4 × 1018 nvt) it appears that corrections for interfering Ca- and K-derived Ar isotopes can be made without significant loss of precision for samples with K/Ca > 1 as young as about 5 × 105 yr, and for samples with K/Ca < 1 as young as about 107 yr. For younger samples the combination of large atmospheric Ar corrections and large corrections for Ca- and K-derived Ar may make the precision of the40Ar/39Ar technique less than that of the conventional technique unless the irradiation parameters are adjusted to minimize these corrections.

    Publication type Article
    Publication Subtype Journal Article
    Title 40Ar/39Ar technique of KAr dating: A comparison with the conventional technique
    Series title Earth and Planetary Science Letters
    DOI 10.1016/0012-821X(71)90214-7
    Volume 12
    Issue 3
    Year Published 1971
    Language English
    Publisher Elsevier
    Description 9 p.
    First page 300
    Last page 308
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