D.M. Unruh M. Tatsumoto D.D. Bogard 1983 <div id="abstracts" class="Abstracts u-font-serif text-s"><div id="ab1" class="abstract author" lang="en"><div id="aep-abstract-sec-id4"><p>Determinations of⁴⁰Ar/³⁹Ar and U-Th-Pb are reported for three clasts from the Abee (E4) enstatite chondrite, which has been the object of extensive consortium investigations. The clasts give⁴⁰Ar/³⁹Ar plateau ages and/or maximum ages of 4.5 Gy, whereas two of the clasts give average ages of 4.4 Gy. Within the range of 4.4–4.5 Gy these data do not resolve any possible age differences among the three clasts.²⁰⁶Pb measured in these clasts is only ∼1.5–2.5% radiogenic, which leads to relatively large uncertainties in the Pb isochron age and in the²⁰⁷Pb/²⁰⁶Pb model ages. The Pb data indicate that the initial²⁰⁷Pb/²⁰⁶Pb was no more than 0.08±0.07% higher than this ratio in Can˜on Diablo troilite. The U-Th-Pb data are consistent with the interpretation that initial formation of these clasts occurred 4.58 Gy ago and that the clasts have since remained closed systems, but are contaminated with terrestrial Pb. The⁴⁰Ar/³⁹Ar ages could be gas retention ages after clast formation or impact degassing ages. The thermal history of Abee deduced from Ar data appears consistent with that deduced from magnetic data, and suggests that various Abee components experienced separate histories until brecciation no later than 4.4 Gy ago, and experienced no appreciable subsequent heating.</p></div></div></div><ul id="issue-navigation" class="issue-navigation u-margin-s-bottom u-bg-grey1"></ul> application/pdf 10.1016/0012-821X(83)90077-8 en Elsevier 40Ar/39Ar and U-Th-Pb dating of separated clasts from the Abee E4 chondrite article