English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The isotopic abundances of uranium and the radium activity ratios of 11 samples of uranium ore from the Colorado Plateau have been measured. No significant variation in the isotopic abundance of the uranium was noted; "within the experimental error, the'average u239^23^ ratio is 137»7< There is a significant variation in the Ra226/Ra223 activity ratios (0.0^ -0.1^3)j which indicates a relatively recent alteration of the ore samples. The variations do not, however, explain the lead-uranium and lead-lead age discrepancies. !/ U. S. Geological Survey, Washington 25, D» C 2/ University of Arkansas, Fayetteville, Ark» Both the published and the unpublished data on the natural variations in isotopic abundance of U235 and U238 in different geologic materials are limited (Nier, 1939a,bj Inghram, private communication). Although Inghram showed that there were no significant variations in the u238/!}235 abundance ratio greater than 0,03 percent (see Katz and Rabinowitch, 1951 )> the possibility has been suggested that the observed variation in the Ra223/Ra226 activity ratios and the discrepancies between the H)206/!!238 and Fb2O7/Pb206 ages may be due, at least in part, to variations in the U23S/U23^ ratio (Kuroda, 1955). For this reason the u23S/U235 ratios of 11 samples from a selected group of uranium deposits of the Colorado Plateau area and uranium ores from two other areas have been isotopically analyzed* These samples represent a wide variety of uranium ore types. Ra223/Ra226 ratios have been determined by Kuroda on many of these samples and H)206/!)238 and Pb2OT/Pb2OS ages have been determined by Stief f and others (1953) on the same samples or similar materials from the same mines. We are indebted to personnel of the Mass Assay laboratory of Union Carbide Nuclear Company, Y-12 Plant, at Oak Ridge, Tennessee, for the uranium isotope analyses. This study is part of a program being conducted by the U. S. Geological Survey on behalf of the Division of Research of the U. S. Atomic Energy Commission. The uranium was completely extracted from the specimens and a minimum of four separate conversions of U308 to We and mass spectrographic determinations were made on each, All the results were compared with those of the Oak Ridge National laboratory "N" Standard (0.7115 wt percent U235 ). The expressed error is the limit of error of the mean in the 95-Percent confidence level. The results shown in table 1 are for 11 ore Ta bl e 1. =Co mp ar is on of th e ra di um a ct iv it y ra ti os an d th e ur an iu m is ot op e ab un da nc es in s am pl es fr om t he Co lo ra do P la te au . Sa mp le no . G S J N GS -6 4 GS -8 7 PK -1 8 AE -1 16 5 IE -1 26 0 AE -1 27 1

Comparison of the isotopic abundance of U235 and U238 and the radium activity ratios in Colorado Plateau uranium ores