The source of radium in anomalous accumulations near sandstone escarpments, Australia

B. L. Dickson*, A. M. Giblin, A. A. Snelling

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The source of Ra has been determined in water samples from four areas in Australia where anomalously high surface concentrations of 226Ra have accumulated from groundwaters. All four anomalies were located adjacent to sandstone formations, and the groundwaters, which were generally all acidic and low in dissolved salts, appeared to be meteoric water with short ground-residence times. Uranium, 226Ra and 228Ra concentrations of waters feeding the anomalous areas were comparable to those found in standing waters within the sandstones. The 226Ra/228Ra isotopic ratios were distributed about a median of 1.1 which suggests that the waters are in contact with rocks with near-normal U/Th ratios and, hence, that the Ra in the anomalies was derived from within the sandstones. The presence of the short-lived Ra isotopes, 223Ra and 224Ra, in high concentrations in most spring waters feeding these anomalies suggests that Ra enters groundwaters by recoil following alpha decay of a precursor parent radionuclide within mineral grains. Thus, although three of the areas were considered prospective for U, the radioactive anomalies studied appear to be due to natural transfer of Ra from the sandstones to the surface environment. In no case were the anomalies related to nearby known or undiscovered U deposits. Accordingly, a geochemical procedure, which includes Ra isotopic measurements, is recommended for evaluating radioactive anomalies for U exploration. This procedure should enable selection of only those anomalies with the highest potential for further exploration by more expensive techniques.

Original languageEnglish
Pages (from-to)385-398
Number of pages14
JournalApplied Geochemistry
Volume2
Issue number4
DOIs
Publication statusPublished - 1987

    Fingerprint

Cite this