Loughborough University
Browse

File(s) under permanent embargo

Reason: This item is currently closed access.

Secondary uranium mineralization in southern Finland and its relationship to recent glacial events

journal contribution
posted on 2014-11-26, 14:29 authored by David Read, Stuart Black, Tracy Buckby, Karl-Heinz Hellmuth, Nuria Marcos, Marja Siltari-Kauppi
Uranium series dating has been carried out on secondary uranyl silicate minerals formed during sub-glacial and post-glacial weathering of Proterozoic uraninite ores in south west Finland. The samples were obtained from two sites adjacent to the Salpauselkä III ice marginal formation and cover a range of depths, from the surface to more than 60 m. Measured ages fall into three distinct groups, 70–100 ka, 28–36 ka and < 2500 yr. The youngest set is associated with surface exposures and the crystals display clear evidence of re-working. The most likely trigger for uranium release at depths below the surface weathering zone is intrusion of oxidising glacial melt water. The latter is often characterised by very high discharge rates along channels, which close once the overpressure generated at the ice margin is released. There is excellent correspondence between the two Finnish sites and published data for similar deposits over a large area of southern and central Sweden. None of the seventy samples analysed gave a U–Th age between 40 and 70 ka; a second hiatus is apparent at 20 ka, coinciding with the Last Glacial Maximum. Thus, the process responsible for uranyl silicate formation was halted for significant periods, owing to a change in geochemical conditions or the hydrogeological regime. These data support the presence of interstadial conditions during the Early and Middle Weichselian since in the absence of major climatic perturbations the uranium phases at depth are stable. When viewed in conjunction with proxy data from mammoth remains it would appear that the region was ice-free prior to the Last Glacial Maximum.

History

School

  • Science

Department

  • Chemistry

Published in

GLOBAL AND PLANETARY CHANGE

Volume

60

Issue

3-4

Pages

235 - 249 (15)

Citation

READ, D. ... et al., 2008. Secondary uranium mineralization in southern Finland and its relationship to recent glacial events. Global and Planetary Change, 60 (3-4), pp. 235 - 249.

Publisher

© Elsevier B.V.

Version

  • VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2008

Notes

Closed access.

ISSN

0921-8181

Language

  • en

Usage metrics

    Loughborough Publications

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC