Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Sources of Rare-Earth Elements and Iron in Paleoproterozoic Iron-Formations from the Transvaal Supergroup, South Africa: Evidence from Neodymium Isotopes

Michael Bau, Axel Höhndorf, Peter Dulski and Nicolas J. Beukes
The Journal of Geology
Vol. 105, No. 1 (Jan., 1997), pp. 121-129
Stable URL: http://www.jstor.org/stable/30079890
Page Count: 9
  • Read Online (Free)
  • Download ($19.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Sources of Rare-Earth Elements and Iron in Paleoproterozoic Iron-Formations from the Transvaal Supergroup, South Africa: Evidence from Neodymium Isotopes
Preview not available

Abstract

Neodymium isotopic data are reported for pure chemical sediments from the Siderian Kuruman and Penge Iron-Formations (IFs) in the Transvaal Supergroup, South Africa. From a large sample set for which petrographical and chemical data was available, we selected samples which best represent the pure chemical sediment and still carry the primary rare-earth element (REE) distribution for isotope analyses. Both the Kuruman IF ( + 1.9 and +1.1) and the Penge IF (+ 0.2 and -0.2) show $\epsilon_{Nd} (2.5 Ga)$ values more radiogenic than published values for epiclastic sediments from the slightly older Black Reef Formation (-5.1 to -3.2). This suggests that REE and iron in the Transvaal IFs were predominantly, though not exclusively, derived from hydrothermal alteration of oceanic crust. The $\epsilon_{Nd} (2.5 Ga)$ value of the Kuruman IF is similar to that proposed for the Hamersley IF in western Australia, suggesting that $\epsilon_{Nd}(t) values of + 1 \pm 1$ were typical of IF-depositing open ocean waters at the Archean/Proterozoic boundary.

Page Thumbnails

  • Thumbnail: Page 
121
    121
  • Thumbnail: Page 
122
    122
  • Thumbnail: Page 
123
    123
  • Thumbnail: Page 
124
    124
  • Thumbnail: Page 
125
    125
  • Thumbnail: Page 
126
    126
  • Thumbnail: Page 
127
    127
  • Thumbnail: Page 
128
    128
  • Thumbnail: Page 
129
    129