W. J. Moore R.D. Rubright J. S. Stacey 1967 <div id="abstracts" class="Abstracts u-font-serif text-s"><div id="ab1" class="abstract author" lang="en"><div id="aep-abstract-sec-id8"><p>A gas-source mass spectrometer has been constructed for the precise measurement of lead isotope ratios. Sixteen analyses on 4 different preparations of the same galena made over a period of 2 months gave 95% confidence limits (per analysis) of<span>&nbsp;</span><i>²⁰⁶Pb/²⁰⁴Pb= 0.080%,<span>&nbsp;</span>²⁰⁷Pb/²⁰⁶Pb= 0.042%and²⁰⁸Pb/²⁰⁶Pb= 0.046%</i>.</p><p>Eight samples from the U.S. mine in the Bingham district have a linear relationship over the 1% range of their²⁰⁶Pb/²⁰⁴Pb ratios. The simplest model fitting these data suggests that the lead was separated from a primary system<span>&nbsp;</span><i>(μ=8.98) 1630±150m.y.</i><span>&nbsp;</span>ago and subsequently mixed with a radiogenic lead of similar age; biotite K-Ar dates for altered intrusive rocks associated with the ores provide an apparent age of mineralization and suggest that isotopic evolution of the lead was terminated about 36 m.y. ago.</p></div></div></div> application/pdf 10.1016/0012-821X(67)90195-1 en Elsevier Precision measurement of lead isotopes ratios: preliminary analyses from the U.S. mine, Bingham Canyon, Utah article