Thermoluminescence measurements on shock‐metamorphosed sandstone and dolomite from Meteor Crater, Arizona: 2. Thermoluminescence age of meteor crater

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Abstract
Thermoluminescence (TL) dating measurements were performed on shock metamorphosed rocks from Meteor Crater, Arizona. IL ages were obtained for eight specimens, four Coconino sandstone and four Kaibab dolomite, which experienced sufficient shock heating during the impact to reset their preimpact TL. Postimpact radiation doses were determined for each shocked fragment from thermoluminescence measurements on quartz mineral separates. Effective radiation dose rates were calculated from concentrations of uranium, thorium, potassium, and rubidium in the rocks and their burial environment and the distributions of these elements as determined by fission track and microprobe analyses. Cosmic radiation dose rates were estimated by altitude scaling of sea level data and were corroborated by TL dosimeter measurements at the crater. The mean TL ages for the two rock types were reasonably concordant, 50,400±2900 and 46,000±3100 years for sandstones and dolomites, respectively. The overall mean age, 49,000±3000 years, is significantly older than the 25,000‐year age estimate based on the inferred correlation of the oldest pluvial episode at the crater with radiometrically dated δ18O maxima.